Study of slurry erosion of different heat treated steel

STUDY ON SLURRY EROSION OF DIFFERENT HEAT-TREATED STEEL A DISSERTATION Submitted in partial fulfillment of the requirements for the award of the degree of INTEGRATED DUAL DEGREE (Bachelor of Technology & Master of Technology) in METALLURGICAL AND MATERIALS ENGINEERING (With specialization in Materials Engineering) By MITUL RAWAT (12216013) DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY ROORKEE ROORKEE- 247667 (INDIA) MAY, 2017 DECLARATION This is to certify that the work which is being hereby presented by me in this project titled “Study On Slurry Erosion Of Different Heat-treated Steel” in partial fulfilment of the award of the degree of Bachelor of Technology and Master of Technology, submitted at the Department of Metallurgical and Materials Engineering, IIT Roorkee, is a genuine account of my own work carried out during the period from May 2016 to April 2017 under the supervision of Dr. Sourav Das, Assistant Professor, Department of Metallurgical and Materials Engineering, IIT Roorkee. The matter embodied in this project report to the best of my knowledge has not been submitted for the award of any other degree elsewhere. Date: 6 May, 2017 Place: Roorkee Mitul Rawat 12216013 CERTIFICATE This is to certify that the above declaration by Mitul Rawat is true to the best of my knowledge. Dr. Sourav Das Assistant Professor Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee 2 ACKNOWLEDGEMENT At the very outset, I would like to express my deep and sincere gratitude to my supervisor, Dr. Sourav Das, Assistant Professor at the Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, for his unceasing encouragement, suggestions, mentorship and continuous support throughout the year long period of my dissertation work at IIT Roorkee. I am also extremely thankful to Dr. Subhankar Das Bakshi, Product Division, Tata Steel, Jamshedpur for providing me the opportunity,mentorship and continuous support to carry out this project work. I am in deep regards to Tata Steel for providing the support and materials for conducting the project work. I am also extremely thankful to Dr. Anjan Sil, Professor and Head, Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, for his guidance and help to carry out this dissertation work. I wish to express my heartfelt appreciation to Mr. Guru Prakash for providing ample guidance and mentorship throughout the year. My earnest regards to all my batch-mates for their companionship through the five magnificent years of our stay at IIT Roorkee. Lastly, my profound gratitude to my family for their love and continuous support, understanding and encouragement. 3 TABLE OF CONTENT DECLARATION 1 ACKNOWLEDGEMENT 1 LIST OF TABLES 7 ABSTRACT 8 INTRODUCTION Tribology and Wear Adhesive Wear Abrasive Wear Mechanism of Abrasive Wear Two Body Abrasion Three Body Abrasion Erosive Wear Solid Particle Erosion Mechanism of Erosive Wear Wear Resistant Steels Acicular Ferrite Testing Cavitation erosion Friction coefficient and surface roughness Effect of impact angle on slurry erosion behaviour Ductile Erosion Stress level in the surface Particle shape and strength Particle concentration in the fluid stream Nature of the carrier gas and its temperature Stress- Strain Analysis Nanoindentation 9 9 9 10 11 11 11 12 14 15 15 15 16 16 17 17 17 20 20 21 21 21 21 LITERATURE REVIEW 22 EXPERIMENTAL PROCEDURE Materials Processing Characterization & Analysis 29 29 29 31 RESULTS AND DISCUSSIONS Wear Analysis 33 34 4 Magnified Surface SEM Images Cross Section SEM Images Waterquenched sample microstructures 43 49 52 CONCLUSION AND FUTURE SCOPE 58 REFERENCES 59 5 LIST OF FIGURES Figure No. Subject Page No. 1 Abrasive Wear 11 2 Sieved Fractions 14 3 Influence of Particle Size 15 4 Influence of Hardness 15 5 Slurry Pot Tester 20 6 Abrasive particle striking a surface and removing material 22 7 Weight Loss when Al is eroded by SiC 24 8 Volume removed (mm3/g abrasive) as a function of VHN 25 9 Surface roughness of the tested specimens 35 10 Slurry Wear Test 36 11 Ploughing 38 12 Relative Erosion 40 13 Testing Sample 43 14 Sand Filtration 43 15 Experimental Setup 44 16 Erosive Wear Chart 46 17 Polished Surface of Samples 49 18 Wear Surface of Samples 49 19 SEM Micrograph 50 6 Figure No. Subject Page No. 20 Slurry Erosion Pot Tester 51 21 Embedded Particle in Annealed Sample 51 22 Ploughing in Annealed Sample 52 23 Lip Formation in Annealed Sample 52 24 Embedded Particle in Water quenched Sample 53 25 Craters in Water quenched Sample 53 26 Cracks in Water quenched Sample 54 27 Ploughing in Water quenched Sample 54 28 Craters in Martensite Matrix 55 29 Chipping in Water quenched Sample 55 30 Cracks in Normalized Sample 56 31 Ploughing in Normalized Sample 56 32 Ridges & Craters in Normalized Sample 57 33 Microvoids formed in Annealed Sample 57 34 Pearlite Deformed on edges in Normalized sample 60 35 XRD of Cross Section 60 36 Comparison of XRD Peaks 61 37 Microstructure- Water Quenched Sample 62 38 Microstructure- Annealed Sample 62 39 Microstructure- Normalized Sample 63 7 LIST OF TABLES Table No. Subject Page No I Wear v/s Element 16 II Abrasive used in slurry erosion test 27 III Quenching & Tempering 36 IV Concentration 42 V Treatment 42 VI Weight Loss Observations 47 VII Relation between Hardness & Wear Rate 47 VIII Weight Loss Percentage 48 8 ABSTRACT The objective of this dissertation is to study the slurry erosion behaviour of Low Carbon alloy steel treated under different heat treatments.Applications of this particular alloy steel includes in earthmoving, mining, and ore processing which are subjected to high erosion. An experimental study was conducted to assess the erosion in wet environments on normalized, annealed and quenched samples of the particular alloy steel. A testing apparatus was constructed based on the slurry pot erosion test method followed by Knuutila.Keeping the same conditions tests were repeated for all samples. This study is focussed on review and testing of wear behaviour for varying hardness and phase. Various wear mechanisms were assessed through scanning electron microscopy analysis. Results were found to be consistent with the inverse relation between Hardness and wear rate. 9 INTRODUCTION Tribology and Wear Tribology is the science and technology put into practice for studying the interaction between surfaces in relative motion.Wear is the progressive loss of materials due to contact between surfaces in relative motion. Damages of wear are twofold[1]. –– Firstly, loss of fromand theconsequently contacting surface reduces the dimension of the ancethe between the materials moving parts, results in high vibration, high noise, component. This often leads to the increased clearance between the moving parts, and reduced efficiency and system malfunction. If dynamic loading is involved, the reduced consequently results incould high vibration, high noise, reduced efficiency and system malfunction. If component dimension promote fatigue fracture, leading to a catastrophic failure. dynamic loading is involved, the reduced component dimension could promote fatigue fracture, to a catastrophic –leading Secondly, the materialfailure. detached from worn surface, known as wear debris, is similarly harmful. It may cause contamination, for example, when a machine for food or beverage – Secondly,hasthe materialwith detached worn surface, when knowntrapped as wear debris, is similarly processing problems wear. Itfrom may act as abrasive inside the contacting harmful.causing It mayfurther cause increased contamination, for example, for foodpipeline, or beverage surface, wear rate. It may alsowhen blocka amachine valve, a critical an processing has problems with wear. It may act as abrasive when trapped inside the contacting oil filter or accumulated in an electrical contacting point,preventing the normal function of a surface, The causing wear and rate.thus It may also blockhave a valve, criticalever pipeline, an oil system. costfurther of wearincreased is enormous, great efforts beena made since the filter ages or accumulated in an electrical contacting point,preventing the normal function of a early of industry, with aims to reduce or eliminate wear. system. The cost of wear is enormous, and thus great efforts have been made ever since the early ages of industry, with aims to reduce or eliminate wear. E.g. In Hard facing dihydrogen monoxide tubes & turbine pump seal joints are coated to obviate brine from eroding pump. E.g. In Hard facing dihydrogen monoxide tubes & turbine pump seal joints are coated to obviate brine from eroding pump. Adhesive Wear Adhesive Wear An adhesive wear[2] model assumes that wear is the result of adhesion between asperities An adhesive wear[2] model assumes that wear is the result of adhesion between asperities followed by fracture. A first simple model of adhesive wear states that the volume of worn followed by fracture. A first simple model of adhesive wear states that the volume of worn material removed Vw as a result of a tribological interaction is directly proportional to the load material removed Vw as asliding result distance of a tribological interaction directly the load F L. However, since is less wear proportional is observed to when the F n and also to the total totalmember sliding ofdistance L. However, less wear is also observed when the hardness ofto thethe softer the tribological couplesince increases, V w can be regarded n and also as inversely proportional to theofhardness H of thecouple material being worn away. hardness of the softer member the tribological increases, Vw can alsoInbesymbols, regardedthe above is represented as FnL H or expressed in terms of the worn volume per unit sliding distance w Vw Fn w= =K L H V w =K where K is the previously introduced wear coefficient. This expression is sometimes called Archard’s law. Although an equation of this form was first proposed by Holm from his studies on electric contacts, Archard first obtained it using a simplified model of the contact interaction described below. Note that if the sliding distance is the result of sliding at constant velocity U, it is then 10 given by L = Ut where t is the sliding time. If Archard’s law is divided by the nominal (apparent) contact area A a , substitutes the sliding distance in terms of sliding velocity and time and solves for the time one gets 1 H pm U K where d = Vw/Aa is the worn depth and pm = Fn/Aa is the mean or nominal pressure. This is an indication of the life of a wearing component in terms of the admissible worn depth and the material and process parameter H, K, pm and U. t=d Abrasive Wear Abrasive wear, sometimes called cutting wear, occurs when hard particles slide and roll under pressure, across the tooth surface. Hard particle sources are: dirt in the housing, sand or scale from castings, metal wear particles, and particles introduced into housing when filling with lube oil. Scratching is a form of abrasive wear, characterized by short scratch-like lines in the direction of sliding. This type of damage is usually light and can be stopped by removing the contaminants that caused it. Abrasive wear is caused by the passage of relatively hard particles/asperities over a surface. Following are few well-known reasons of abrasive wear mechanisms[3] : - Micro-cutting : sharp particle or hard asperity cuts the softer surface. Cut material is removed as wear debris. - Micro-fracture : generally occurs in brittle, e.g. ceramic material. Fracture of the worn surface occurs due to merging of a number of smaller cracks. - Micro fatigue : When a ductile material is abraded by a blunt particle/asperity, the worn surface is repeatedly loaded and unloaded, and failure occurs due to fatigue. - Removal of material grains : Happens in materials (i.e. ceramics) having relatively week grain boundaries. Fig 1 Abrasive Wear Here Wear Rate depends directly on Load and inversely on hardness. 11 Q=kW/H Another principle that is used to classify abrasive wear is related to the stresses found in the process and how they impact the abrasive particles (Gant et al. 2004). If the wear process involves only two materials it is known as two-body abrasive wear. If extraneous abrasive particles are used one has three-body wear. Another principle is used classify abrasive wear is strength related tothree the stresses in the Depending on the that attack angletoand the interfacial shear modes found of abrasive process and are how they impact particles (Gant et If the wear metals: process wear usuallythe abrasive encountered in al. 2004). ductile involves only two materials it is known as two-body abrasive wear. If extraneous abrasive • Ploughing: Ridges form along the sides of wear track. particles are used one has three-body wear. • Wedging: A short wedge forms in front of the abrading asperity. attack angle and chip the interfacial strength threeabrading modes of asperity. abrasive •Depending Cutting: onA the long ribbon-like forms inshear front of the wear are usually encountered in ductile metals: • Ploughing: Ridges form along the sides of wear track. • Wedging:of Abrasive A short Mechanism Wearwedge forms in front of the abrading asperity. • Cutting: A long ribbon-like chip forms in front of the abrading asperity. 1. Cutting : According to experimental work on abrasive wear, cutting of worn surfaces may be affected by two main factors; the presence of a lubricant and the geometry of Mechanism of Abrasive Wear the grit. Cutting : According to experimental work on abrasive wear, cutting of worn surfaces may 2. Fracture be affected by two main factors; the presence of a lubricant and the geometry of the 3. Fatigue : This wear mechanism leads to separation of particles from a surface in the grit. form of flakes Fracture 4. Grain Pull Out : Is a mode of wear consisting in primarily intergranular fracture where Fatigue : This leads separation particles from a surface in the form one or two wear grainsmechanism are removed at a to time (Kajdas of 1990). of flakes Grain Pull Out : Is a mode of wear consisting in primarily intergranular fracture where Two Body Abrasion one or two grains are removed at a time (Kajdas 1990). This type takes place when hard particles or grit eliminate material from the opposing Two Body Abrasion surface. be when best described by thinking of a material being or removed This typeThis takescan place hard particles or grit eliminate material fromdisplaced the opposing surface. through a plowing or cutting operation. This can be best described by thinking of a material being displaced or removed through a plowing or cutting operation. Three Body Abrasion Abrasion Three Body This occurs occurs when when the the particles particles are are unconstrained unconstrained and and are are able able to to slide slide down down and and roll roll on on aa This surface. The The environment environment of of contact contact defines defines whether whether the the classification classification of of wear wear isis aa closed closedor or surface. open type. type. An An open open wear wear environment environment takes takes place place when when surfaces surfaces are are adequately adequately displaced displacedtoto open become free free of of each each other.E.g. other.E.g. Iron Iron Oxide Oxide wear wear debris debris isis generated generated in in pistons pistons which whichleads leadstoto become three body body abrasion abrasion leading leading high high wear wear and and energy energy loss. loss. three Due to to rolling rolling action, action, abrasive abrasive wear wear constant constant isis lower lower compared compared to to 2-Body 2-Body abrasion. abrasion. Due Generally K2B K2B == 0.005 0.005 to to 0.05; 0.05; and and K3B K3B == 0.0005 0.0005 to to 0.005; 0.005; Generally Mostly found found in in mining mining industry industry & & in in machines machines working working in in deserts. deserts. Mostly Erosive Wear In situations in which wear is caused by the striking of hard particles either carried by a gas or a liquid (usually water), it is defined as erosion. In the second case where a liquid is the 12 particle carrier, the terminology used is slurry erosion (Hutchings 1992) (Kajdas et al. 1990). The parameters[4] influencing the extent of the erosion are associated with the impact conditions and the properties of the impacting particles and target surface.Properties of the impacting particles, such as size, density, sharpness and hardness, can markedly influence the severity of erosion.However, there are exceptions to the rule e.g. wind-blown quartz tends to be more rounded than quartz that has been keyed together by vegetation or artificially sized by crushing (see Fig. 2). Investigation of the influence of hardness has also involved the use of closely sieved sizes and it has been shown that erosion is strongly dependent upon hardness as measured by diamond pyramid micro-hardness Indentations on individual grain. In addition, different materials exhibit different types of size dependence; engineering alloys and resilient plastics exhibit an initial increase in erosion with particle size till the onset of a saturation plateau where it is independent of size (see Fig. 3). The onset of the plateau is itself dependent upon velocity. An essentially brittle material like glass exhibits a power law relation with erosions i.e. ϵ=¿ a d2 whilst erosion of resins and composite materials like fiberglass increases particle size but does not exhibit the plateau for the range investigated. 13 Sheldon and Finnie suggested that erosion is proportional to the reciprocal of the plastic flow stress which is itself related to hardness, and give some evidence to support the relation in a later paper-is. However, heat-treatment of AISI 1045 steel and a tool steel to obtain a 411 range of hardness produced no significant change in erosion. In analysing the erosion of a variety of materials, it was shown that some brittle materials tend to become less resistant at higher hardnesses whereas the opposite is true of ductile materials. 14 However, in comparing different materials, it is essential to define the impact conditions because brittle materials are usually superior under glancing impacts whereas ductile materials are best under normal impact. Solid Particle Erosion Removal of material from surface due to high speed impact of solid particles. Impact wear is the gradual wastage of material due to repeated impact by particulate streams (erosive wear) or by continued hammering with a hard object (percussive wear). In solid particle erosion, the kinetic energy of impacting particles is transferred to the worn surface where is transformed into work of plastic deformation. Worn particles may then by removed by ploughing, wedging or cutting (ductile materials) or by fracture (brittle materials). By equating the kinetic energy of impinging particles to the work of plastic deformation and recognizing that only a fraction β of impacts results in worn particles the following expression has been obtained for the erosion ratio E (mass of worn particles divided by mass of erosive particles) due to a total mass m of erosive particles impinging the surface with velocity U rU 2 E=b 2H where ρ is the density of the worn material. Note that is again akin to Archard’s equation but with the load Fn superseded by ρU2 . Wear coefficients for erosive wear range between 10−5 and 10 −1 . An expression identical to Archard’s law can be obtained by recognising that the term FnL represents a sliding energy Es. Consider n identical particles of mass m impacting a surface with the same velocity v. Their individual kinetic energy is 12 mv2 of the total kinetic energy of the particles that is only a fraction β results in material removal.Hence the impacting energy resulting in wear is given by Ei = bEk = b[½] mv2. Consequently, utilizing this impact energy in lieu of the sliding energy into Archard’s equation yields Vw = KimpactEk/H The wear coefficient in this case can then be interpreted as the fraction of all impact events that results in material removal. 15 The wear volume is estimated per impact cycle. Specifically for the impact of a slug with mass m of duration ti and peak force F0 , onto a surface moving tangentially with speed u, the worn volume is given by Vw = k u ti F0S / 2pH where S = pmu/mF0 ti is the slip factor and m is the friction coefficient between the slug and the surface. Mechanism of Erosive Wear It is generally accepted that the mechanisms of erosion[4] are different for ductile and brittle materials, but the precise details of the processes are still far from understood. In one of the earliest studies, drew an analogy with the cutting action of a machine tool operation to generate equations relating erosion to impact angle. For normal impacts, damage was resulting in in workworkconsidered to be caused by repeated plastic deformation of the surface resulting are eventually eventually detached detached from hardening and propagation of small cracks, so that fragments are erosion under under glancing glancing impacts impacts the surface. Finnie used a very similar model to explain the erosion but developed equations ignoring the damage that can occur under normal impact. if perfectly elastic behaviour Considering the erosion of brittle materials, he suggested that if occurs, cracking is caused by Hertzian stresses set up on impact and subsequently material is removed as the cracks interact, The theories of Finnie and Martlew both predict that erosion is dependent upon the square of velocity in contrast to the slightly higher exponent usually prevalent. Model depends on[5] 1) particle properties (size, shape and hardness) particle velocity, particle 2) fluid flow conditions (density of the fluid, angle of impingement, particle concentration in the fluid, nature of the fluid and temperature of the fluid), and 3) surface properties(hardness and microstructure, geometry component, fatigue, melting point). Wear Resistant Steels There Resistant are two categories Wear Steels of steels which are erosion resistant and used in case of bearings.In one case is hardenedofthroughout their martensite orinbainite.In other cases There areSteel two categories steels which aresections erosion using resistant and used case of bearings.In therecase is a Steel soft core inside with tenacious layers outside obtained by surface hardening. one is hardened throughout their sections using martensite or bainite.In other cases there is a soft core inside with tenacious layers outside obtained by surface hardening. Acicular Ferrite Acicular ferrite is a microstructure of ferrite in steel that is characterised by needle-shaped crystallites or grains when viewed in two dimensions. The grains, actually three-dimensional Acicular Ferrite in shape, have a thin lenticular shape. This microstructure is advantageous over other Acicular ferrite because is a microstructure ferrite inwhich steel increases that is characterised microstructures of its chaoticofordering, toughness. by needle-shaped crystallites or grains when viewed in two dimensions. The grains, actually three-dimensional in shape, have a thin lenticular shape. This microstructure is advantageous over other microstructures because of its chaotic ordering, which increases toughness. 16 Acicular ferrite is formed in the interior of the original austenitic grains by direct nucleation on the inclusions, resulting in randomly oriented short ferrite needles with a 'basket weave' appearance. Acicular ferrite is also characterised by high angle boundaries between the ferrite grains. This further reduces the chance of cleavage, because these boundaries impede crack propagation. Testing Slurry pot erosion testers, in which the samples are attached at the ends of arms pointing out from a centre hub with bearings, see Fig. In tests, the sample holders rotate and the samples travel along a circular path in the slurry volume, and collisions between the sample surfaces and the slurry particles will lead to erosive wear [Wood & Wheeler 1998, Knuutila et al. 1999, Lathabai et al. 1998]. The tests are often conducted under vacuum for gas erosion testing. The method has been used, for instance, for studies on the erosive wear resistance of blades of helicopter rotors and gas turbine compressors [Wood & Wheeler 1998, Maozhong & Jiawen 2002]. Fig 5. Slurry Pot Tester Cavitation erosion Cavitation erosion is a type of erosion which causes repetitive nucleation, growth and collapse of bubbles in the liquid .Cavitation erosion is caused when there is a relative motion between the solid and a fluid.Due to relative motion, bubbles are formed.These bubbles implode near the solid surface.When bubbles implode a micro jet of liquid is directed to solid surface.The solid surface will absorb the impact energy and subsequently there will be plastic deformation or weight loss on the surface.This may lead to erosion of the solid surface.Cavitation erosion is found in underwater components like pipes,ships,pumps,etc 17 Friction coefficient and surface roughness Adhesive wear theory suggests that the friction coefficient can be expressed by the equation μ = τf/σy when there exits a film on the specimen surfaces. That is to say, the friction coefficient is proportional to the shear strength of the interface τf and inversely to the compression strength of the metal matrix. Therefore, the small the τf and the larger the σy, the smaller the friction coefficient. It is generally believed that thermo-chemical treatments strengthen the metal matrix by the diffusion zone thus increasing the σy on the one hand and reducing the τf on the other hand because of the intermetallic structure of the surface compound layer. The combination of these two factors could decrease the friction coefficient significantly. Effect of impact angle on slurry erosion behaviour Mass of particles striking each specimen per one revolution is given by[6]; Where, θo: the angle between the surface plane of the specimen and the horizontal plane l: is the length of wear specimen surface in m, An: is the area of orifice in m2, Cw: is the weight fraction of solid particles in the water, ρw: is the water density in kg / m3, D: is the rotational diameter of the wear specimen m, Q: is the volume flow rate of slurry in m3/min., and N: is the rotational speed of the wear specimen in rpm. Ductile Erosion There are a no of factors which may influence ductile erosion[4] : ● Angle of impingement. ● Particle rotation at impingement. ● Particle velocity at impingement. ● Particle size. ● Surface properties. ● Shape of the surface. ● Stress level in the surface. ● Particle shape and strength. ● Particle concentration in the fluid stream. ● Nature of the carrier gas and its temperature. We consider the two dimensional case shown in Fig.6 where an idealized particle of unit 18 width is considered.Although the treatment can be extended to a particle of arbitrary shape. The volume displaced by this idealized particle is approximately the integral of yt dxt (where xt, yt are the coordinates of the particle tip) taken over the period in which cutting occurs. Fig.6 Abrasive particle striking a surface and removing material Particle velocity The equations predict V α U2 and this is observed experimentally to a first approximation. However, more careful observation shows the relation to be more nearly U 2.4 in many cases. The reason or reasons for this discrepancy are not clear. The explanations offered have been particle fragmentation at higher velocities and size effect (to be discussed later in connection with particle size). Curiously for brittle solids, with no scatter in strength, the predicted relation is V α U2.4. Particle size One of the most intriguing aspects of erosion is that the volume removed by a given mass of abrasive grains is independent of particle size for particles larger than about 100 pm. For particles below this size, the erosion process becomes less and less efficient as the particle size is decreased. This is a fortunate aspect of erosion because as particles become smaller it becomes more difficult to separate them from the fluid stream. The physical reasons for this size effect are still not clear. Some of the factors which one might consider are : 19 (a) Fragmentation of larger particles leading to more efficient cutting than with smaller particles. (b) Grain size of the metal eroded. (c) Oxide coating on the metal eroded. (d) Change in the geometry of the cutting process as smaller particles are used. (e) A true physical size-effect such that regions below a certain size show an increase in strength values. Fig.7 Weight Loss when Al is eroded by SiC Properties of the surface Many particles only plow the surface and in fact remove little if any material. Based on the careful study of Mulhearn and Samuel a more realistic figure for c was found to be 0.1. For 10 pm particles the volume removal will be less by a factor of perhaps five. 20 Fig. 8. Volume removed (mm3/g abrasive) as a function of Vickers Hardness when annealed metals are eroded by 60 mesh SiC at α = 20° and V=250ft (From Finnie, Wolak and Kabil). Theshape shapeofofthe thesurface surface The curiousfeature featureofof ductile ductile erosion erosion is is that that ripples appear on the AAcurious the surface surface when when materials materials are are erodedatatan anangle angleatator or near near that that for maximum erosion. The simple eroded simple analysis analysis of ofplastic plasticcutting cutting thatwe wehave havepresented presented isis also also capable capable of explaining this phenomenon that phenomenon and and of of predicting predicting the the effect surface on erosion rates. effect ofof surface curvature erosion rates. Stress level in the surface By contrast solids, we would expect that high residual stresses would have little Stress levelto in brittle the surface influence on ductile erosion. In we a few exploratory tests high it wasresidual found that residual stresses no By contrast to brittle solids, would expect that stresses would havehad little effect on erosion whileerosion. applying stress by external bending moments thestresses test ledhad to a influence on ductile In the a few exploratory tests it was found thatduring residual barely detectable increase in applying erosion. As result by thisexternal aspect of erosionmoments was not pursued further. no effect on erosion while thea stress bending during the test led to a barely detectable increase in erosion. As a result this aspect of erosion was not Particle pursuedshape and strength further. The simple analysis of ductile erosion which has been presented is based on rigid abrasive particles that do not fracture during cutting. While most of our work was carried out with angular silicon carbide grains, the same tests carried out with rather more “blocky” aluminum Particle shape and strength oxide grains gave very similar results. The analysis could be extended to rigid particles of other The simple offracture ductile of erosion which has been presented is based on of rigid abrasive shapes, again analysis excluding the particle, by selecting appropriate values K and I. It is particles that do not fracture during cutting. While most of our work was carried out with clear from the work of Tilly and colleagues that particle shape and strength play a angular silicon carbide grains, the same tests carried out with rather more “blocky” aluminum oxide grains gave very similar results. The analysis could be extended to rigid particles of other shapes, again excluding fracture of the particle, by selecting appropriate values of K and I. It is clear from the work of Tilly and colleagues that particle shape and strength play a 21 role in erosion and in particular it is seen that fracture of the particle may drastically change the shape of the curve of volume removal as a function of angle. Particle concentration in the fluid stream A small effect of particle concentration on erosion has been reported several times in the literature.To my knowledge no satisfactory explanation for this effect has yet been offered. Nature of the carrier gas and its temperature The effect of temperature on erosion is small in the normal range of operating temperatures for the alloys studied. In retrospect this result is perhaps expected. Extremely high temperatures, of the order of the melting point, can be computed for the material being removed in ordinary “room temperature” erosion tests, so the additional temperature imposed in “elevated temperature” testing may not be significant.More recent fundamental studies have shown that at very high strain rates a thermal deformation process appears to be involved. Little has been published on the effect of the carrier gas itself. Stress- Strain Analysis From XRD study of wear sample stress-strain analysis is plotted.Rietveld method is used to obtain the stress present in matrix. Using Rietveld method a curve fitting is performed by Data analysis which allows to determine relation of diffraction pattern with stress. Nanoindentation The surface damage in case of wear can be determined by observing the fracture produced during indentation.Several methods are present to perform indentations on surface of material.Vickers Indentation and Nanoindentation is one such method to perform fracture and obtain hardness v/s depth curves. 22 LITERATURE REVIEW Knuuttila et al.[8] had designed the slurry erosion pot test in 1999 for studying slurry erosion of thermal oxide spray coatings.They varied pH of the slurry to obtain a relation between erosion and pH of slurry. Importantly, It was concluded that large grit size and high density of thermal oxide caused higher wear rates.Slurry erosion tests were carried out using a slurry pot tester.t. TABLE -II Recent studies studies have have shown shown that that the the aluminum phosphate sealing treatment has a strong effect Recent on the the residual residual stress stress state state of of the the coating transferring it towards compressive stress state. And on since residual residual stresses stresses have have an an effect effect on hardness and wear resistance they should be since be considered as as an an important important factor factor together together with the known bonding effect of the aluminum considered aluminum phosphate. phosphate. Rambabu Rambabu et et al.[6] al.[6] investigated investigated the the sand sand slurry erosive wear behaviour of Ni-Cr-Si-B coating deposited deposited on on mild mild steel steel by by flame flame spraying process under different test conditions.The slurry pot conducted pot tester tester was was used used to to evaluate evaluate wear wear behaviour of the coating and mild steel. They conducted erosive speeds (600, (600, erosive wear wear test test using using 20 20 and and 40 40 per cent silica sand slurry at three rotational speeds 800 cent 800 and and 1,000 1,000 rpm). rpm). Slurry Slurry erosive erosive wear wear of the coating showed that in case of 20 per cent silica silica sand sand slurry slurry weight weight loss loss increases increases with with increase in rotational speed while in other case sand sand slurry slurry weight weight loss loss first first increases increases with with increase in rotational speed followed by marginal decrease decrease in in weight weight loss loss with with further further increase increase in rotational speed from 800 rpm. Wear ratio between wear. between the the uncoated uncoated sample sample and and coated coated sample was used as a parameter to compare wear. Scanning Scanningelectron electron microscope microscope (SEM) (SEM) study study of of wear surface showed that loss of material from the the coating coating surface surface takes takes place place by by indentation, crater formation and lip formation and its fracture. fracture. Wear Wear of of Ni-Cr-Si-B Ni-Cr-Si-B coating[8] coating[8] was was found found to take place by pitting, plowing and indentation. indentation. High High slurry slurry concentration concentration and and rotation speed produce extrusion and plastic deformation of soft nickel dominated deformation of soft eutectic matrix. Finnie have explained explained Finnie et et al.[4] al.[4] has has done done extensive extensive work on the slurry erosion of metals.They have the is the mechanism mechanism of of erosion erosion of of ductile ductile and brittle material.It was concluded that for erosion is maximum as maximum atat 30° 30° for for ductile ductile and and 90° for brittle metals.Ploughing of surface was explained as the ductile metals.They also also discussed the mechanisms for erosion of thecutting cuttingaction actionforfor ductile metals.They discussed the mechanisms for erosion of 23 metals.In cutting erosion, a lip is formed at the beginning when erodent particles hit the surface.Subsequently other erodent particles deforms the lips into platelets.These chips are cut off by subsequent impact and causes weight loss.Erosion for brittle materials is explained as mechanism of fragmentation and impact. Diwakar et al.[10] has investigated slurry erosion behaviour of nitrided steel and related slurry erosion with the hardness of metal.In experiment surface was nitrided, causing formation of carbides, nitrides and carbonitrides.Thus surface became harder and core was soft, having better wear resistance to slurry erosion. Sundararajan concluded that repeated experiments have clearly shown that neither heat treatment nor cold working of the target has any effect on erosion resistance. In another review Naim and Bahadur reported that the prior cold working of the samples increases the incubation period for the onset of erosion. Also due to an increase in the initial level of cold working, a higher rate of erosion was observed for both the normal and the oblique impact conditions. Goretta investigated the erosion resistance of copper, nickel and 304 stainless steel with sharp alumina particles. He concluded that work hardening improved the erosion resistance of the copper, which has high ductility. Higher hardness also improves the erosion resistance of the material if it retains sufficient ductility. Wen at al.[11] carried out a study of erosion resistance of AISI 403 steel.The steel was austenitized at 1000℃ for 120 min and rolled at 950℃ for reduction ratio of 0,20,40 and 60.The steel with higher reduction ratio exhibited the minimum erosion.When reduction ratio is higher ,than rolling causes finer grain formation.Steel with finer grains are more hard than steel with coarse grains.Also Finer grain inhibits the crack propagation and hence steel is more resistant to erosion in comparison to steel with coarse grains. Chauhan et al.[19] had carried out the study of slurry erosion of Nitronic steel and compared it with martensitic stainless steel.It was concluded that nitronic steel had more resistance to slurry erosion in comparison to 13/4 martensitic stainless steel. Wen et al.[11] had carried out a study on thermo-mechanical-treated steel which was tempered under different temperatures.It was observed that steels with different tempering temperatures & mechanical treatments exhibhited different resistance of slurry erosion behaviour.Test results of differently heat treated metals showed that hot rolling is an attractive process for improving erosion resistance. The thermal-mechanical-treated samples exhibit higher slurry erosion resistance for all impinging angles compared to that obtained by conventional quenching treatment without rolling. The variation tendency of the erosion rate versus the impinging angle for samples rolled with different degrees of reduction was found similar in that the erosion rate initially increases and then decreases as the impinging angles increase from 15° to 90°, reaching a maximum at approximately 30°. After impingement erosion, the surface morphologies of the samples exhibit many long furrows and ridges at a low impinging angle of 30°. At a high impinging 24 angle of 90°,it was found the samples exhibited a worn surface with abundant overlapping and irregular concavities. The surface hardness of the samples after impingement erosion increased due to the enhanced effects of both work hardening and the formation of strain induced martensite. Dong et al. & Chattopadhyay et al. have reported that the main erodent particle in water is slit.The slit plays an important role in the erosion of surface of underwater components. Slit is basically SiO2 which has high hardness of 750 VHN. Hutchings et al. & Clark et al. have reported that the slurry erosion damage is due to the erosion action of solid particles suspended in water. Amarendra et al. carried out a study on different heating cycle on 13/4 martensitic stainless steel . It was found that microstructure influences the slurry erosion behaviour of steels.It was found that the slurry erosion resistance of steel can be improved by optimizing the heat treatment cycle.When austenitizing temperature was increased and soaking time was increased the carbide in steel was well dispersed in the matrix.This dispersed carbide particle impedes the erosion rate of steel.It is evident from this work that microstructure plays an important role in the behaviour of an alloy to slurry erosion. Hasan et al. studied the effect of various heat treatments on slurry erosion behavior of 13Cr4Ni martensitic stainless steel (MSS) at different impingement angles. The heat treatments given, involved the austenitization of cast steel at temperatures of 950° C, 1000° C and 1050° C for different soaking durations of 2, 4 and 6 h at each temperature. This was followed by oil quenching and tempering for 1 h at a 600° C air cooled. The tempered MSS showed 34% lower wear rate due to increased toughness and hardness. S. M. Ahmed et al.[7] studied effect of impact angle on Slurry Erosion Behaviour and mechanisms of Carburized AISI 5117 Steel.Tests were carried out with particle concentration of 1 wt %, and the impact velocity of slurry stream was 15 m/s. Silica sand having a nominal size range of 250 – 355 µm was used as an erodent.Results showed that carburizing process of steel increased the erosion resistance and hardness compared with untreated material for all impact angles. At high impact angles, the resolved normal stress will produce the accumulated damage mainly from fatigue, micro forging, and extrusion processes. These processes can only produce slighter erosion damage than that caused by cutting removal at low impact angles. D.C. Wen et al.[13] studied erosion and wear behaviour of nitrocarburized DC53 tool steel. He concluded that maximum erosion rate appears at an impinging angle of 30 ◦ for all specimens. In this condition, plough grooves and cutting lips appear in the eroded surface; however, the traces of erosion on the untreated specimen are wider and deeper.As holding time of Nitro Carburization increased the erosion rate decreased, but the wear properties 25 including the wear loss, friction coefficient, wear mechanism and the width of the abrasion grooves did not changed significantly. The morphologies of the eroded surfaces of the NC-0 and NC-2 specimens with the maximum erosion rate (at impinging angle of 30 ◦ ) are shown in Fig.9. Due to the relatively low hardness, the surface of the NC-0 specimen is severely deformed during the erosion test. Obvious plough grooves and cutting lips appear in the eroded surface, and wider and deeper erosion traces can be viewed in Fig. 9(a). The erosion tracks on the eroded surfaces of the NC-2 specimen are found to be shallow and superficial. Both plough grooves and cutting lips can be discerned in Fig. 9(b), but the erosion damage is less than that in the NC-0 specimen. Fig 9. Surface roughness of the tested specimens afore and after the wear tests. M.K. Manoj et al.[14] synthesized Fe-TiC composites of varying concentrations. Under observation microstructures of composites showed TiC particles in the matrix of transformed ledeburite (pearlite and cementite). The quenching and tempering process increases the surface roughness of the base material from 0.4m to 0.9m. TABLE-III. Quenching & Tempering Composite Vol. % of TiC Vickers hardness VHN Density(g/cc) A 4% 622 7.62 B 6% 635 7.60 C 9% 216 7.15 White Cast Iron 0% 456 7.65 White cast iron was included in the test for comparison purport as white cast iron is a low cost commonly used wear resistant material in mineral processing and mining industries. 4% TiC composite-A and 6% TiC composite-B showed minimum wear rate or maximum wear resistance. Wear rate of composite-C containing 9% TiC is maximum as graphite flakes act as potential sites for facile abstraction of material. 26 Fig.10 Slurry Wear Test Teng et al.[18] studied erosion behaviour of tempered martensite stainless steel.The results showed that, in single particle erosion tests, the main mechanisms that cause problems are micro-cutting and deformation craters at low and high incident angles, respectively. In repetitive particle erosion tests, grain boundary cracking was one of the main fracture mechanisms. The platelet mechanism also obviously affected at high incident angle erosion. Materials tempered at 573–673 K, tempered martensite embrittlement (TME) occurred, which caused serious boundary cracking and grain broken-down. The serious erosion damage showed at medium incident angle for this material that result in combine of cutting,deformation crater, and cracking mechanism. The maximum erosion rate of material occurred at an incident angle of 30 and the deepest erosion penetration occurred at an incident angle of 45.They utilized mechanics analysis to get results, which are summarized as follows: cutting erosion occurs at a low incident angle and deformation erosion occurs at a high incident angle. Islam et al.[16] studied effect of microstructure on erosion behavior of carbon steel.Solid particle erosion of steel is a function of abrasive particle properties, target material, erodent velocity, abrasive feed rate, impact angle and the environment. Steel microstructure, which directly influences its hardness and ductility, plays an important role in determining the erosion rate. In this study, the effect of microstructure on the erosion of AISI 1018 (pearlite + ferrite) and AISI 1080 (pearlite) steel was investigated. Particle velocities and impact angles employed were as follows: 36, 47, 56 and 81 m/s at 30, 45, 60 and 90, respectively. Nanoindentation was performed and it was found that hardness of the various microstructures had an inverse relationship to erosion rate. Surface and sub-surface examinations were conducted using scanning electron microscopy. 27 Fig 11. a)Ploughing on right b)Embedded Particle in Pearlite c)Alumina embedded in Ferrite Ploughing, metal cutting and delamination are identified as dominant mechanisms during erosion of AISI 1018 and AISI 1080 steel. It was observed that pearlitic and ferritic microstructures respond differently to erosion and that the orientation of pearlite plates with respect to the impinging particle affects the extent of metal removal.. Abd-Elrhman[12] studied effect of impact angle on slurry erosion behaviour and mechanisms of carburized AISI 5117 steel using whirling-arm rig. The study is mainly focused on studying the erosion wear resistance properties of AISI 5117 steel after carburizing at different impact angles. Plough grooves and cutting lips appears for acute impact angle, but the material extrusions are for normal impact angles. The erosion traces are wider and deeper for untreated specimens comparing by the shallower and superficial ones for the carburized specimens. Jan Suchanek et al[16] studied influence of microstructure on erosion resistance of steels which were modified in a broad range by changing the conditions of their heat treatment. Increasing pearlite share in the structure of annealed carbon and low-alloyed steels had a positive effect on their erosion resistance. The growing carbon content in the tested hardened steels increased their erosion resistance.Since slurry erosion depended upon following factors (a) Impact conditions—impact angle, particle impact velocity. (b) Characteristics of a carrying medium and particle mixture—type, size, shape and hardness of particles, type of carrying medium, chemical effect of medium on surface layers of the eroded material, amount of particles and their distribution in the stream of liquid. 28 (c) Characteristics of the eroded material—combined physical & mechanical properties, macro With a growing content of carbon the erosion resistance increases for selected parameters of their tests (see Fig.12). Fig.12 Relative Erosion Twigg et. al [23] studied nanoindentation investigation of micro-fracture wear mechanisms in polycrystalline alumina. The initiation of surface damage under point loading has been investigated in polycrystalline alumina materials using low load continuous depth-sensing indentation equipment (nanoindentation). Pure alumina and liquid phase sintered materials containing 10% by weight of magnesium or calcium monosilicate have been examined and data obtained from plots of displacement as a function of load assessed in relation to erosive wear rates. In the pure alumina material, discontinuities (“pop-ins”) in the load-displacement trace appear to be associated with the induction of radial cracking around a plastic impression. 29 EXPERIMENTAL PROCEDURE Materials Particular Steel was casted at Tata Steel, Jamshedpur in cast V29185 with the following concentration of elements : TABLE IV - Concentration of Elements Element C Mn S Si P Conc(%) 0.1469 0.86 0.008 0.015 0.024 Al Ti Cr N 0.058 0.012 0.025` 55ppm Sand was obtained from construction site.Additionally PC Steel slabs were obtained to supplement need of additional bars. Processing From the cast three different slabs were prepared of size 7cm * 2.5cm * 0.3cm. Varying heat treatment was given to three samples with following conditions : 1. Annealed Sample : Heated to 930°C and then cooled slowly. 2. Normalized Sample : Heated to 930°C and then air cooled for 4 hours. 3. Water Quenched Sample : Heated to 930°C and then water cooled for 1 hours. After heat treatment the top surfaces of all samples was polished with 400 grit paper. Processed samples were sent to IIT Roorkee were further testing and characterization was performed. TABLE V - Heat Treatment Sample Treatment Hardness Cooling Sample 1 Water Quenched 53 HRC Water cooled Sample 2 Annealed 24 HRC Furnace cooled Sample 3 Normalized 30 HRC Air Cooled Samples obtained were grinded and cut according to the experimental setup requirements. Indented from top and bottom by cutting corners up to 0.3cm in length and 0.5cm in breadth. Additionally 5 samples of PC steel were grinded and cut to match the need of three additional dummy samples required for setup. 30 Fig 13 . Testing Sample The sand was dried in Oven at 250°C for 12h.The sand was filtered to obtain uniform size of particle size around 210- 310 microns.Sieve sizes used were Tyler 20/28/48/65.Sand present in Tyler no. 48 Sieve was used for erosion. Concentration of slurry was fixed and 1kg of sand was mixed with 10 kg of water with continuous stirring to obtain uniform composition. Fig 14 . Sand Filtration Weight of samples are measured precisely upto 0.0001 gm before and after the experiments.There were 4 four groves in holder at different angles of 30°,45°,60° & 90°.In one grove the experimental sample was fixed and in other three standard dummy samples were fixed.The experimental setup and holder are shown below. 31 Fig 15 . Experimental Setup The speed of tester was kept at 500 rpm. With one experimental sample and three standard dummy samples, the holder is rotated in the slurry mixture at a fixed speed for a duration of 1hr.After running the test sample is cleaned and weighed.The weight loss was calculated for each time.The test was repeated for same setup for 12 hours. For all three samples the tests were repeated and data was recorded in tabular format.Plot of Mass Loss v/s time was obtained from data.Further other parameters like Weight Loss % was calculated.With density calculations wear rate predictions and plot were obtained. Another test with same conditions was conducted with same samples without abrasion with 400 grit paper for 10 hours.Results were recorded and compared with Abrasive samples. Characterization & Analysis Surface Analysis : Under FESEM,Top Surface of wear samples were observed. During Surface observation various cracks and deformations were observed. Length of cracks was measured and noted.Deformations were further classified into ridges,cracks,lifts and displacement of Mandrel. All three samples were observed and compared in similar fashion. Cross Section Analysis : Under FESEM, Side surface of wear samples were observed.During analysis deformations and Tribolayer were observed.Pearlite spacing was also measured and compared among the three samples. XRD Analysis : Under XRD analysis various peaks were observed and studied.Intensity of peaks among the three samples were compared and inferences were noted. 32 Microstructure Investigation : Subsequently Microstructure of after-processed normalized,annealed and water quenched steel samples were obtained using optical microscope.The following steps were involved for obtaining the microstructure 1) Polishing the surface by belt grinder. 2) Polishing the sample with 1/0 emery paper. 3) Turning the polished surface by 90 and polishing the sample by 2/0 emery paper. 4) Turning the polished surface by 90 and polishing the sample by 3/0 emery paper. 5) Turning the polished surface by 90 and polishing the sample by 4/0 emery paper. 6) Polishing the polished surface by cloth polishing using alumina powder (See the size) until scratches are removed. 7) Etching the polished surface with 2% Nital Solution for few seconds. 8) Observing the polished surface under the optical microscope and obtaining digital micrographs. Same procedure was repeated for all three samples. Vickers Hardness Test : Polished samples were cleaned and hardness was obtained using Vickers Hardness Tester. Hardness values were obtained both sides erosion facing surface and erosion opposing surface. Surface Roughness Measurement : Initial surface roughness and final surface roughness was measured using profilometer. 33 RESULTS AND DISCUSSIONS Fig 16. Erosive Wear Charts 34 Wear Analysis From the experiment it has been observed ● Water Quenched Sample shows least wear with declining weight loss. ● All three curves follow similar trajectory. ● Initially Weight loss is more due to material undergoing strain hardening.Later the weight loss decreases due to saturation in strain hardening. ● After 10hrs of continuous testing a decrease in weight loss is observed in all three samples signifying occurrence of corrosion. ● Slope of Weight Loss V/s Time gives wear rate in mg/hr with values mentioned in Table VIII. ● Angle was kept constant at 30°.Resulting into maximum erosion due to ductile erosion. ● Comparing slopes of all three samples it was observed that Annealed Sample was weared most followed by Normalized Sample and Water Quenched Sample. ● A relation between slope of Wear curve and hardness was devised described in Table VIII. ● Comparing the slopes and Hardness of all three samples, it can be concluded that Wear rate is inversely proportional to Hardness.The as-followed heat treatment has successfully been able to reduce erosive wear as shown in table IX. 35 36 Fig 17. Comparison of Wear Testing Charts (Polished v/s Abrasion) TABLE VI - Wear Testing Abrasive Samples Weight Loss (in mg) Duration (in Annealed( ± 0.56) Normalized( ± 0.41) hr) Water 0.56) 0 0.00 0.00 0.00 1 26.72 12.90 4.59 2 29.69 18.84 9.27 3 36.83 26.54 12.39 4 43.55 31.91 20.70 5 49.43 34.16 20.16 6 49.82 38.63 9.99 7 53.27 41.21 26.18 8 59.39 44.57 27.86 9 63.29 50.99 24.45 10 65.15 56.03 27.62 11 68.27 59.36 30.11 12 94.00 64.97 34.91 Quenched( ± TABLE VII - Wear Testing Polished Samples Weight Loss (in mg) Duration (in Annealed( ± 0.56) Normalized( ± 0.41) hr) Water 0.56) 0 0.00 0.00 0.00 1 5.70 7.59 6.36 2 7.83 7.05 6.12 Quenched( ± 37 3 9.81 8.88 7.50 4 11.91 10.47 9.18 5 12.75 11.22 9.42 6 14.34 12.42 11.04 7 15.30 13.77 11.76 8 16.56 14.13 12.42 9 19.83 14.19 14.61 10 20.70 16.56 14.82 TABLE VIII - Hardness Measurements Hardness(VHN) Water Quenched( ± 17) Annealed( ± 3) Normalized( ± 5) Before Erosion After Erosion Before Erosion After Erosion Before Erosion After Erosion 1 514 896 243 300 160 238 2 494 894 254 304 156 238 3 454 882 227 306 157 228 4 487 933 243 305 155 233 5 594 910 249 310 150 227 Mean 508 903 243 305 155 233 S. No. TABLE IX . Relation between Hardness & Wear Rate Sample Annealed Slope(mg/hr) 4.95 155 ± 3 VHN Hardness Normalized Water Quenched 4.45 2.66 243 ± 5 VHN 508 ± 17 VHN TABLE X . Surface Roughness - Water Quenched Sample Before Erosion m Rz μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ Points After Erosion m Rq μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ m Rq μ¿ ¿ ¿ m Rz μ¿ ¿ ¿ 1 0.04 0.5 0.05 0.43 4.5 0.79 2 0.04 0.4 0.05 0.49 6.8 1.07 3 0.11 1.5 0.19 0.22 2.6 0.32 4 0.06 0.6 0.09 0.62 6.4 1.02 38 5 Mean 0.05 0.5 0.07 1.07 8.3 1.68 0.06 0.7 0.09 0.57 5.72 0.98 TABLE X . Surface Roughness - Normalised Sample Before Erosion m Rz μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ Points After Erosion m Rq μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ m Rq μ¿ ¿ ¿ m Rz μ¿ ¿ ¿ 1 0.07 1 0.11 0.12 1.3 0.17 2 0.06 0.9 0.1 0.08 0.8 0.11 3 0.06 0.5 0.07 0.1 1.2 0.15 4 0.05 0.5 0.07 0.08 0.8 0.11 5 0.06 0.5 0.07 0.11 1.4 0.16 0.06 0.68 0.08 0.098 1.1 0.14 Mean TABLE X . Surface Roughness - Annealed Sample Before Erosion m Rz μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ Points After Erosion m Rq μ¿ ¿ ¿ m Ra μ¿ ¿ ¿ m Rq μ¿ ¿ ¿ m Rz μ¿ ¿ ¿ 1 0.04 0.5 0.05 0.12 1.3 0.17 2 0.05 0.4 0.04 0.08 0.8 0.11 3 0.04 0.4 0.005 0.1 1.2 0.15 4 0.06 0.6 0.09 0.08 0.8 0.11 5 0.05 0.5 0.07 0.11 1.4 0.16 0.05 0.48 0.05 0.1 1.1 0.14 Mean Calculations Volume of Sample Dimensions : l= 2cm; b=0.3cm ; w=0.3cm Vol = 2*(2cm*0.3cm*0.3cm)+0.3cm*5cm*2.5cm =4.11 cm3 Error Calculations : Weighing Balance (Least Count) = 0.005 mg Profilometer (Least Count) = 0.01 μm❑ TABLE - XI. Weight Loss Percentage Duration (in hr) Annealed Normalised Water Quenched 39 0 0.00% 0.00% 0.00% 1 0.07% 0.03% 0.00% 2 0.07% 0.05% 0.02% 3 0.09% 0.06% 0.03% 4 0.11% 0.08% 0.04% 5 0.12% 0.08% 0.05% 6 0.12% 0.09% 0.06% 7 0.13% 0.10% 0.05% 8 0.15% 0.11% 0.06% 9 0.16% 0.12% 0.07% 10 0.16% 0.14% 0.06% 11 0.17% 0.14% 0.07% 12 0.23% 0.16% 0.08% 40 FigF 41 Fig.18 Comparison of Surface Roughness Fi g.19 Comparison of Hardness of Abrasive Samples Before and after erosion 42 Fig 20. Polished Surface of Samples Fig 21. Weared Surface of Samples 43 Fig.23 SEM Micrographs of all three samples 44 Fig 24 Slurry Erosion Pot Tester Magnified Surface SEM Images I. Annealed Sample Fig.25 Embedded Particle in Annealed Steel Matrix 45 Fig.26 Ploughing in Annealed Sample Fig.27 Lips formation followed by chipping of material in Annealed Sample 46 II. Water Quenched Sample Fig.28 Embedded particle in Hard Matrix of Water Quenched Sample Fig.29 Craters due to concentrated impact of particles at one position in Water Quenched Sample 47 Fig.26 Cracks & Crater Formation in Water Quenched Sample Fig.30 Ploughing and ridges are visible in Water Quenched Sample 48 Fig.31 Crack in Martensite Matrix Fig.32 Secondary Wear - Chipping of Material in Water Quenched Sample 49 III. Normalized Sample Fig.33 Cracks propagation in Matrix of Normalized Sample Fig.34 Secondary Wear : Ploughing followed by cracking in Normalized Sample 50 Fig.35 Ridges and craters on surface of Normalized Sample Cross Section SEM Images Fig.36 Microvoids formed in Annealed Sample 51 Fig.37 Pearlite Deformed on edges in Normalized sample 52 XRD Analysis Fig.38 Comparison of Diffraction Peaks - Surface From XRD analysis,following has been observed ● Peaks of most deformed material has the highest intensity. ● As visible in Fig.38, Water quenched sample has least intensity peaks signifying minimum deformation. ● Peaks of Annealed sample have highest intensity due to maximum deformation and wear. Normalized sample has medium deformation and hence medium intensity of peaks. ● As visible in Fig.38, Impression of more deformation of normalised compared to annealed is reflected in high order peaks of ferrite. 53 Waterquenched sample microstructures Fig.39 Erosion Opposing Surface(20 μm ) - WQ Sample Fig.40 Erosion Facing Surface(20 μm ) - WQ Sample Fig.41 Erosion Opposing Surface(50 μm ) - WQ Sample 54 Fig.42 Erosion Facing Surface(50 μm ) - WQ Sample Fig.43 Erosion Opposing Surface(100 μm ) - WQ Sample Fig.44 Erosion Facing Surface (100 μm ) - WQ Sample 55 Normalised sample microstructures Fig.45 Erosion Opposing Suface - Normalised Sample (20 μm ) Fig.46 Erosion Facing Surface - Normalised Sample (20 μm ) Fig.47 Erosion Facing Surface - Normalised Sample (50 μm ) 56 Fig.48 Erosion Opposing Surface - Normalised Sample (50 μm ) Fig.49 Erosion Opposing Surface - Normalised Sample (100 μm ) Fig.50 Erosion Facing Surface - Normalised Sample (100 μm ) 57 Annealed Sample Microstructures Fig.51 Erosion Opposing Surface - Annealed Sample (20 μm ) Fig.52 Erosion Facing Surface - Annealed Sample (20 μm ) Fig.53 Erosion Opposing Surface - Annealed Sample (50 μm ) 58 Fig.54 Erosion Facing Surface - Annealed Sample (50 μm ) Fig.55 Erosion Opposing Surface - Annealed Sample (100 μm ) Fig.56 Erosion Facing Surface - Annealed Sample (100 μm ) 59 CONCLUSION AND FUTURE SCOPE Erosion in ductile metals occurs via ploughing, lips formation ,cracks, ridges and chipping. The harder the surface is lower will be the wear rate. Along with wear, phenomenon of embedding of particles into the matrix is observed in martensite sample due to high hardness.Diffraction peaks depict the extent of deformation in material.Larger the intensity of diffraction peaks, more is deformation. Also from wear rate it is quite clear water quenched being hardest among the three sample suffered least erosion. Comparison of wear rates and hardness further justifies the inverse relation between hardness and erosion. Future scope of this study includes study of solid particle erosion using advanced morphological apparatus.This will benefit in understanding the fracture mechanisms and impact of sand particles at nano levels. 60 REFERENCES [1] C. X. 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