A Review On Slurry Abrasion Of Hard Faced Steels

Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 5 (2018) 3524–3532 www.materialstoday.com/proceedings ICMPC 2017 A Review On Slurry Abrasion Of Hard Faced Steels Sarfraj Ahmeda*, O P Thakarea, Ruchir Shrivastavaa, Sumit Sharmab, S G Sapatec a c Dept of Mechanical Engg, RSR-RCET, Kohka, Bhilai-490024, India b Dept of Mechanical Engg, SSCET, Junwani, Bhilai-490020, India Dept of Metallurgical & Materials Engg, VNIT, Ambazari, Nagpur-440010, India Abstract Abrasive particles suspended in a liquid causes wear to the components through which it flows. Slurry abrasive wear takes place mainly in steel piping, extruders and slurry pumps. This paper shows the contributions done by many researchers on slurry abrasion of steels previously. The steels of five varieties namely En-31 steel, Stainless steel 316-L, Martensitic steel, Low alloy steel and Martensitic stainless steel have been selected for study. The effect of operating parameters such as Normal load, Sliding distance and Slurry concentration was investigated. Wear rate was different for different materials depending upon experimental parameters and material properties. Keywords – Slurry abrasion, Volume loss, Slurry concentration, Normal load. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 7th International Conference of Materials Processing and Characterization. 1. Introduction: Tribology deals with the science of friction wear and lubrication. When a body having relative motion in contact with other body or bodies, it experiences friction which leads to the loss of material from softer body. This process of material removal is called wear and the body is said to be worn out. There may be different forms of wear such as abrasive wear, Erosive wear, Fatigue wear, Adhesive wear etc. About 50 % of the failure in industries occurs due to abrasive wear. The progressive loss of material from the component by abrasive particles suspended in a liquid medium is known as slurry abrasion. The component such as slurry pump, extruders, pipes, coal slurry nozzles etc. are subjected to slurry abrasive wear in power plants, steel plants and mining industries. Hard facing is the method for improving the wear life of components. The material of required properties is deposited on the surface of component by welding process [1, 2]. The slurry abrasive wear behaviour of various steels has been investigated by different researchers under three body abrasive wear condition. * Corresponding author. Tel.: +918962783534 E-mail address: [email protected] 2214-7853© 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 7th International Conference of Materials Processing and Characterization. Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 3525 Wear rate of steels depends upon the operating variables such as normal load, sliding distance, slurry concentration, particle hardness and particle size. Material hardness, microstructure and composition of material also affect the wear rate. The silica sand was used as abrasive particles for experiments. The weight loss method is used to determine the wear resistance of material. The difference in weight of the specimen before and after test gives weight loss and it is converted into volume loss. Scanning electron microscope was used to study the morphology of abraded surface after test [3]. 2. Materials and Experimental: The apparatus used for experimentation were slurry abrasion Tester, Ducom India. It consists of a slurry abrasive chamber in which the rubber lined steel wheel is enclosed, specimen holder and slurry. Diameter of the wheel is 178 mm and thickness is 12.7 mm. The max. speed of the rubber lined wheel is 250 ± 5 rpm. The slurry temperature is maintained by circulating coolant through double walled jacket. The normal load applied by the specimen over the rubber wheel is measured by a load cell having capacity 450N. The required material was in the form of electrode and it was deposited over mild steel plate by welding process. Mixture of Silica sand and distilled water used as a abrasive slurry, After the test was over the specimen were removed from slurry chamber cleaned with alcohol and weighed. The difference in initial and final weight of the specimen gives mass loss and volume loss (mm³) was also determined. This apparatus follows the standard ASTM G105. A Schematic diagram of slurry abrasion Tester is shown in fig-1. Fig 1 – Schematic of slurry abrasion tester S.G Sapate, A.D. Chopde, P.M. Nimbalkar and D.K Chandrakar [4] carried slurry abrasion testing of EN-31 steel. The steel specimen was quenched from 830 ± 3ºc with a soaking time of 1 hr. Then the specimen designated as A, B. C and D was tempered at temperature of 210º, 300º, 410º, and 550º respectively, after water quenching. The composition of En- steel is as follows – C 0.95%, Si 0.27%, Mn 0.72%, Cr 1.42%, P 0.018% and S 0.016%. The bulk hardness of samples were measured by using Rockwell hardness tester at a load of 150 kg. An average of three readings is taken for A – 57HRC, B – 50HRC, C – 42 HRC and D – 32 HRC. Silica sand of size distribution of 300μm- 5% + 212μm-95% was selected as abrasive. The microstructure of different specimens as shown in fig.-2 (a) (b) and (c) (d). 3526 Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 Fig 2 – Microstructure of specimen A, B, C & D The slurry abrasion tests were performed by varying parameters. i.e sliding distance (RPM), load and slurry concentration. Test for all specimen (A,B,C,D) were conducted under four condition-very mild (load 35 N, 500 RPM and 150 % condition) , mild (70 N load , 1000 RPM and 150% slurry condition), (95 N load, 1500 RPM, and 150% slurry) and very (125 N load , 2000 RPM and 150% slurry). The fig-3 (a) (b) shows volume wear less of heat treated specimen of En-31 steel A,B,C and D Vs. the product of sliding distance (S) and normal load (L). The slop of the line in each case represent volume wear rate in (mm³/N-m) of specimen. The volume wear in mm³/N-m of specimen A, B, C and D were 0.0007, 0.0009, 0.0012 and 0.0014 respect. An increase in Bulk hardness from 32 to 57 HRC has resulted in two times increase in slurry abrasion resistance. Under very severe test condition volume wear rate was 2.35 times as compared to that under very mild test condition for all specimens. The coarser carbides in specimen B, C and D attributed to decreasing hardness of the matrix with increasing tempering temperature [5]. Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 3527 Fig – 3(a, b) Worn Surfaces of specimen D & A V. Balasubramanian, R.Varahamoorthy and S. Babu [6], investigated the slurry abrasive wear of stainless steel. It has hardness of 372 HVN. The microstructure of stainless steel 316-L is shown in Fig.-4. Fig – 4 Microstructure of stainless steel 3528 Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 Based on test parameter five levels of test were selected - Very low (N - 400 RPM, SC-10%, D - 0.15mm, T - 30º), Low (N -800RPM, SC-20%, D - 0.3 mm, T - 45ºc), Middle (N -1200RPM, SC - 30%, D - 0.6 mm, T - 60ºc ), High (N - 1600RPM, SC - 40%,D - 1.2 mm, T - 75ºc) and Highest (N - 2000RPM, SC - 50%, D - 2.4 mm, T - 90ºc). All the specimens were tested for a 10 KM distance of travel. It has been found that with increase in abrasive particle size the wear rate increases. This is because the coarser abrasive particles enhance abrasion action due to large area of contact. If the slurry is higher, then the abrasive wear rate is higher and vice versa. Because at higher slurry concentration particles have a greater tendency to slide against the surface. When the speed of rotation is higher the abrasive particles are displaced away from the center of specimen causing less material removal and if the speed is low the wear rate is more. The wear rate decreases marginally when the slurry bath temperature increases from 30ºc to 60ºc, the wear rate increases slightly when the slurry bath temperature increases from 60º to 90ºc. At higher temperature the slurry will become little viscous and it causes more abrasion on the metal surface. Although temperature has little effect on wear rate. SEM analysis of worm surfaces shows heavily deformed surfaces produced by rolling abrasion and plastically deformed surfaces produced by grooving abrasion. The worm surface of specimen is shown in Fig – 5. . Fig – 5 Worn surface of the specimen . S G Sapate, A. Selokar and N. Garg [7], conducted slurry abrasion wear testing on martensitic steel (Iron-carbonchromium alloy steel). The chemical composition of weld deposited steel was carbon-46%, Si-0.71%, Mn-0.37%, Ph-0.025%, S-0.008%, Cr- 8.45% and Vd-0.48%. The microstructure of the material is shown in Fig-6. The Bulk hardness of the specimen is 496 Hv30. The test specimen based on parameter were designated as, A(L-35N, SC40%, N - 500Rpm, D - 53-64μm), B (L-70N, SC-80%, N - 1000Rpm, D - 125-150μm), C (L-95N, SC -120%, N 1500Rpm, D - 212-250μm) and D (L - 125N, SC - 150%, N - 200Rpm, D - 250-300μm). The dependence of the wear volume loss (Ǫ) on Test severity parameter (TSP) was expressed as Ht Where, S = Sliding distance, L = Normal load, Ac =Area of worm out crater, SC = Slurry concentration, D = Avg. abrasive particle size, Ha = Hardness of abrasives, Ht = Hardness of target material, m = exponent and k = Constant. Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 3529 Fig – 6 Microstructure of steel showing martensite The test severity parameter not only takes into account the operating variables like sliding distances, slurry concentration and normal load but also the properties of abrasive particle and material. Scanning electron microscope analysis revealed that, At lower load, slurry concentration and sliding distance the material was primarily removed by ploughing mechanism and At higher load, slurry concentration and sliding distance the material was primarily removed by cutting as seen in Fig-7 (a) (b). Fig – 7 Worn out surfaces of specimens A & D S.G. Sapate and Jagdish Raut, [8] investigated the slurry abrasive behavior of low alloy steel. The composition of material are as follows - Carbon - 0.16%, Si - 0.6%, Mn - 15, Cr - 4.1%, S - 0.02, Mo - 1.96 and Ni - 0.9%. The Bulk hardness of the specimen was found to be 42.12 HRC. The microstructure is shown in Fig-8 3530 Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 Fig – 8 Microstructure of low alloy steel The volume loss increased linearly with sliding distance. The volume loss increased by increasing sliding distance, slurry concentration, normal load and abrasive particle size. The slurry abrasive volume loss exhibited power law dependence on particle size. V = K. dm Where V= Volume loss , K=constant, d= Avg. particle size. The silica sand particles of different sizes is shown in Fig – 9 (a)(b) & (c)(d) Fig – 9 SEM Images of silica sand particle (a) 53-73 µm (b) 125-150 µm (c) 250-300 µm (d) 300-425 µm The experiments were carried out to study the effect of load (35, 70, 95 and 120 N), sliding distance (500, 1000, 1500 and 200 Rpm), SC (40, 80, 120 and 150 %) and particle size (50 -70, 125 -150, 250 - 300 and 300 - 425 μm) on slurry abrasion. It was found that volume loss increase more than twenty times when the silica sand size was increase from 53 -73 μm to 300 - 425 μm. The SEM analysis shows that mechanism of material was ploughing and micro-cutting as seen in Fig – 10[9]. Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 3531 Fig – 10 Abraded surfaces of specimens at 120 N (A) & at 40% (D) Avishkar Rathod , S.G. Sapate, and S. Ahmed, [10] carried slurry abrasion testing on martensitic stainless steel. The composition of material are – carbon - 0.483%, Mn - 0.87%, Si - 1.07%,S-0.011, P - 0.021, Cr - 15.9, Ni - 3.64, Fe – Balance. The microstructure of specimen is shown in Fig -11. Abrasive particles were selected in the range of 250 – 300 μm. Parameters are load ( 35, 70, 95& 120 N), SC (40, 80, 120 & 150%) at constant sliding distance 2000 RPM. When the load is increased from 35 to 120 N, Silica sand particle fractures generating additional fine particles which lead to increasing in wear volume loss. Fig – 11 Microstructure of martensitic stainless steel At higher slurry concentration of 150%, the volume loss is more as compared to volume loss at higher load of 120 N, for same sliding distance of 2000 Rpm. The SEM analysis of worn surfaces revealed that the material was removed due to ploughing, cutting and indentation and shown in above Fig 11. 3. 1. Conclusion: It was found that for En – 31 steel volume wear rate showed an increasing trend from specimen A to D, i.e with decreasing hardness. Under very sever slurry abrasion test condition volume wear rate parameter was 2 times as compared to that under very mild test condition. The material was removed by micro ploughing which was reflected in lower wear rate of specimen A with finer martensitic microstructure. The coarser carbide in specimen B, C and D did not apparently contribute to abrasion resistance and the material was removed by 3532 2. 3. 4. 5. Sarfraj Ahmed et al./ Materials Today: Proceedings 5 (2018) 3524–3532 cutting. The effect of normal load on slurry abrasion volume loss was more pronounced as compared to that of slurry. When the abrasive particle size is large, the rate of wear is greater and when the abrasive particle size is small, the rate of wear is lower. At higher slurry concentration wear loss is more as compared to at lower slurry concentration. Slurry bath temperature has very little influence on slurry abrasive wear. The effect of slurry concentration on wear loss is more pronounced as compared to other parameters. The material was removed mainly due to indentation and rolling abrasion. When the slurry concentration was increased from 40% to 150% then the volume wear loss increased from 2.4487 mm³ to 29.100 mm³. The volumes wear loss increased from 20.5229 mm³ to 40.30 mm³ when the load was increased from 35 N to 125 N. The volume loss depends more on slurry concentration than on normal load. By increasing test severity parameter the volume loss increased from 0.259 mm³ to 77.5 mm³. The SEM analysis revealed mechanism of material removal which was ploughing and micro cutting under very mild and very severe conditions. The slurry abrasion volume loss increases nearly 15 times when slurry concentration was increased from 40 % to 150 %. An increase in normal load from 35 N to 125 N resulted in volume loss to increase by more than 2 times. When the particle size was increase from 53-79 µm to 300-425 µm then the volume loss increased more than 20 times. The important mechanisms of material removal were found to be ploughing and cutting. At 200 revolutions and at 120 N load, when slurry concentration increased from 40% to 150 % the wear volume loss increased nearly 15 times. At 2000 revolution and at 150 % slurry concentration, when the load is increased from 35 N to 120 N then the wear volume loss increase near 3 times. The effect of slurry concentration on wear loss was more pronounced as compared to normal load. The important mechanism of material removal was ploughing, micro-cutting and indentation. References: [1] G. W. Stachowiak, A. W. Betchelor, Engineering Tribology, Butterworth Heinemann, 2013. [2] I. M. Hutchings, Tribology, Friction and wear of engineering materials, Edward Arnold, 1992. [3] T Akira, H Furukawa, Y Minami, Development of abrasion resistance pipe for slurry transportation, NKK Tech Rev, 2001. [4] S.G Sapate, A.D. Chopde, P.M. Nimbalkar and D.K Chandrakar, Effect of Microstructure on Slurry abrasion response of En-31 Steel, Mater & Des, 2008; 29:613-21. [5] O.P. Modi, D. P. Mondal, H. K. Khaira, Abrasive wear behavior of a high carbon steel – effects of microstructure and experimental parameters and correlation with mechanical properties, Mater Sci & Engg, 2003; A343:235-42. [6] V. Balasubramanian, R.Varahamoorthy and S. Babu, Abrasive slurry wear behavior of stainless steel surface produced by plasma transferred arc hard facing process, 2008; 202:3903-12. [7] S.G. Sapate, A. Selokar, N. Garg, Experimental investigation of hard faced martensitic steel under slurry abrasion conditions, Mater & Des, 2010; 31:4001-06. [8] Sanjay G Sapate, Jagdish Raut, Investigations on wear by slurry abrasion of low alloy steel, Proc of Int. Conference on Advances in Mechanical Engineering, 2011; 93-97. [9] I. Sevim, IB Eryurek, Effect of abrasive particle size on wear resistance in steels, Mater & Des, 2006; 27:173-81. [10] S.G. Sapate, Avishkar Rathod, S. Ahmed, Effect of Experimental variables on Tribological properties of martensitic stainless steel, IJMIE, 2012; Vol-2, Iss-3, 25-29. [11] Lin He, CJ Jhang, An investigation of the role of secondary carbides in martensitic steel during three body abrasion wear, Wear, 1994;16:103-9.