articles by Journal of Welding Science and Technology of Iran (JWSTI)
Iranian Institute of Welding and Non Destructive Testing, 2023
The miniaturization and compaction trends in electronic equipment and the removal of lead (Pb) el... more The miniaturization and compaction trends in electronic equipment and the removal of lead (Pb) element from solder alloys due to environmental considerations have created a great challenge in the field of designing and developing of new solder alloys. Therefore, researchers have recently focused on composite solder alloys using reinforcing particles to improve the reliability of leadfree solders. In this research, SAC0307 solder alloys (99 wt.% Sn, 0.3 wt.% Ag, and 0.7 wt.% Cu) with different percentages of cobalt microparticles were made by the Accumulative Roll Bonding (ARB) method. Then, the effect of the particles on wettability, microstructures and mechanical characteristics of solder alloys was investigated. The lowest contact angle was 23•in 0.2 wt.% cobalt sample. By adding cobalt to the solder matrix, the size of intermetallic compounds (IMCs), Cu6Sn5 and Ag3Sn, decreased and the percentage of eutectic phases increased. The shape of the interfacial intermetallic compounds changed from scallop to layer shape by adding cobalt, and their average thickness increased about 13-71% in composite samples. The shear strength of solders increased up to 38% by enhancement of cobalt microparticles in the solder alloy containing 0.4 wt.% cobalt; however, shear strength was decreased in the composite solder containing 1 wt.% cobalt due to the agglomeration of microparticles. The shear fracture surfaces showed that the nature of the fracture changed from ductile fracture in the form of elongated dimples to brittle fracture in the form of cleavage with the increase in the percentage of cobalt microparticles. The composite solder alloys containing 0.2-0.4 wt.% Co have the best wettability behavior and tensile shear strength.
Iranian Institute of Welding and Non Destructive Testing, 2023
The purpose of this research is to investigate the change of rotational speed and traverse speed ... more The purpose of this research is to investigate the change of rotational speed and traverse speed on the microstructure and mechanical properties of the joint in friction stir welding of aluminum 1050 and 316L stainless steel. For this purpose, the microstructure, thickness of intermetallic compounds, hardness and tensile test on the joint were investigated. The proper selection of welding parameters leads to the creation of a joint with suitable metallurgical and mechanical properties. In this research, two rotational speeds of 560 and 900 rpm and four traverse speeds of 60, 80, 100 and 125 mm/min were performed. The microstructure consisted of four areas of the base metal, heat affected zone, thermo-mechanical affected zone and stir zone. In all the samples, the stir zone (SZ) contained a recrystallization microstructure with fine equiaxed grains. According to the Energy dispersive X-ray Spectroscopy results, an IMC layer formed in the joint interface. The hardness of the stir zone in all samples was higher than the aluminum base metal due to the formation of recrystallization fine equiaxed grains and the presence of steel particles. The best sample in terms of mechanical properties, mocrostructure and joint quality was obtained in the conditions of rotation speed of 900 rpm and advance speed of 125 mm/min. The strength was equal to 84 MPa with 77% efficiency.
Iranian Institute of Welding and Non Destructive Testing, 2023
In the present study, friction stir processing (FSP) technique was carried out on the AA2024 shee... more In the present study, friction stir processing (FSP) technique was carried out on the AA2024 sheet at different traverse speed (63 to 250 mm/min) and rotation speed (315 to 800 rpm). The temperature and grain size of stirred zone (SZ) were measured and their relationship was analyzed and effect of FSP parameters on the grain size of SZ was determined. Experiment and analytical investigations revealed that SZ grain size complies the exponential temperature-dependent relationship and can be defined the mathematical equation. Calculations indicate that a change in operational variables (rotation and traverse speeds) makes no variation in strain rate, and it is constant.
Iranian Institute of Welding and Non Destructive Testing, 2023
In the present study, friction stir processing (FSP) technique was carried out on the AA2024 shee... more In the present study, friction stir processing (FSP) technique was carried out on the AA2024 sheet at different traverse speed (63 to 250 mm/min) and rotation speed (315 to 800 rpm). The temperature and grain size of stirred zone (SZ) were measured and their relationship was analyzed and effect of FSP parameters on the grain size of SZ was determined. Experiment and analytical investigations revealed that SZ grain size complies the exponential temperature-dependent relationship and can be defined the mathematical equation. Calculations indicate that a change in operational variables (rotation and traverse speeds) makes no variation in strain rate, and it is constant.
Iranian Institute of Welding and Non Destructive Testing, 2023
As one of the important pillars of the fourth industrial revolution, metal additive manufacturing... more As one of the important pillars of the fourth industrial revolution, metal additive manufacturing (AM) technologies provide a disruptive approach to digital manufacturing. Laser powder bed fusion (LPBF), as one of these technologies, has great potential in producing geometrically complex and high-performance parts. In recent years, the manufacturing of aluminum alloy parts using this technology has attracted much attention. However, their manufacturing still faces some challenging issues. One of the most serious issues encountered in the manufacturing of aluminum alloys, especially high-strength grades, is solidification cracking. In the present investigation, the formation mechanisms of solidification cracking, and the associated effective factors were reviewed. Controlling the solidification microstructure and grain refinement, using the addition of small quantities (<1 wt.%) of micro-or nano-sized particles to the initial alloying powder, was suggested as the most effective method for reducing solidification cracking. These particles act as nucleation sites, prevent grain growth, pin grain boundaries, and with the help of factors that provide constitutional supercooling can effectively minimize solidification cracking. Eventually, effects of various additives in grain refinement and their associated mechanism in reduction of solidification cracks of high-strength aluminum alloys by LPBF is presented.
Iranian Institute of Welding and Non Destructive Testing, 2023
In this research, friction stir welding of aluminum 1050 to copper with variable speed was invest... more In this research, friction stir welding of aluminum 1050 to copper with variable speed was investigated. For friction stir welding, rotational speeds of 900 and 1200 rpm and traverse speeds of 36, 63, and 125 mm/min were used. In order to check the phases and microstructure, scanning electron microscope analysis, X-ray spectrometry, and hardness testing were used. The disturbance zone included Al 2 Cu 3 , Al 4 Cu 9 , AlCu 4 , Al 2 Cu, and AlCu phases. The results showed that the formation of intermetallic phases and severe plastic deformation in the welding area caused an increase in hardness. The highest hardness value in the stirred area was 97.8 Vickers at a rotation speed of 900 rpm and an advance speed of 36 mm/min.
Iranian Institute of Welding and Non Destructive Testing, 2023
Optimization of Stir Friction Welding parameters such as linear and rotational speed of the tool ... more Optimization of Stir Friction Welding parameters such as linear and rotational speed of the tool can be effective to a large extent in improving welding properties. In this research, welding of two sheets of Aluminum of Al-7075 and Al-6061 were validated based on theoretical relations and numerical simulation. The simulation of the contact characteristics of the workpieces with the tool was done using the contact algorithms available in the Ansys software. From the FEM, rotational and linear speed and diameter of the tool were selected as design variables, and multi object optimization was carried out with genetic algorithm and RSM to reach the lowest tool temperature and residual stress.The parametric analysis of FSW of the threaded and non-threaded tool pins showed that the generated heat has proportional and inverse relation with rotation and linear speed of tool respectively. Tool with a diameter of 20 mm showed minimum residual stress in the workpiece. By increasing welding speed, the temperature curves become more compact and the effect of thread on heat generation was more evident in all cases at lower heat input.
Iranian Institute of Welding and Non Destructive Testing, 2023
This study aimed to investigate the effect of electron beam welding parameters on the microstruct... more This study aimed to investigate the effect of electron beam welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between 17-4PH stainless steel and Ti6Al4V alloy. For this purpose, the welding of these two alloys was performed with an copper interlayer with a thickness of 1 mm. Two different welding speeds of 0.7 and 0.9 m/min with four levels of beam offset (0, 0.2, 0.4 and 0.6 mm) from the center of the interlayer towards the steel were used to accomplish the experiments. The results show that by using the copper interlayer with thickness of 1 mm, the cracks caused by the formation of intermetallic compounds are removed from the weld pool. At the interface between the titanium and the weld pool, at the beam offset of 0 and 0.2 mm, a solid solution of copper and TiCu 2 intermetallic compounds is formed, while at the beam offset of 0.4 and 0.6 mm, a solid solution of copper and TiCu intermetallic compounds is formed. The weld pool, at the beam offset of 0 and 0.2 mm, consists of TiCr 2 +TiFe 2 intermetallic compounds while at the beam offset of 0.4 and 0.6 mm, solid solution of iron (α-Fe), solid solution of copper and TiCu intermetallic compounds are formed. The highest value of hardness is observed at the interface between the weld pool and the titanium alloy, as well as at the interface between the weld pool and the steel, which is due to the presence of intermetallic compounds with high hardness in these regions. By increasing the welding speed and the beam offset, the hardness value decreases, which is due to the reduction of brittle intermetallic compounds in the joint structure. By increasing the beam offset from 0.4 mm to 0.6 mm at the speed of 0.7 m/min, the shear strength increases from 180 MPa to 210 MPa and at the speed of 0.9 m/min, the shear strength raises from 230 MPa to 250 MPa. The welded sample with the welding speed of 0.9 m/min and the beam offset of 0.6 mm has the highest shear strength equal to 250 MPa. The failure in all samples happened at the interface between the weld pool and the titanium alloy, which shows that the weakest region in the joint is this interface.
Iranian Institute of Welding and Non Destructive Testing, 2022
One of the most dangerous industries is welding and inspection. Risk assessment is a rational pro... more One of the most dangerous industries is welding and inspection. Risk assessment is a rational procedure for determining the probable repercussions of prospective incidents on people, materials, equipment, and the environment. The risk assessment identifies the efficacy of selected control mechanisms and offers essential data for risk reduction, risk management, control system enhancement, and risk response planning. The current study identified 13 dangerous parts of the "hot crack" and "cold crack." The discovered dangers were then ranked by expert academics in the welding and inspection industries using the fuzzy best worst method (FBWM). A fuzzy method has been developed to address risk uncertainty and minimize decision inconsistencies. The findings indicate that the primary risk factors for weld metal hot cracking in order of importance are "frozen structure, separation, high tensile stresses in the weld metal, material composition, bonding, preheating, high flow intensity, high-thickness workpiece, and weld pollen form." And "the quantity of hydrogen in the weld metal, high tensile stresses, a vulnerable structure, and a relatively low temperature" are all factors in cold welding of weld metal. The study's results may be used to guide the selection of solutions, remove the primary dangers, and establish security policies in the welding and inspection industries.
Iranian Institute of Welding and Non Destructive Testing,, 2023
Galvanic corrosion is an ever-present problem in all different environments, particularly in tank... more Galvanic corrosion is an ever-present problem in all different environments, particularly in tanks. The goal of this project is to develop a finite element model that can be used with experimental data to characterize the
Iranian Institute of Welding and Non Destructive Testing, 2023
This study aimed to investigate the effect of electron beam welding parameters on the microstruct... more This study aimed to investigate the effect of electron beam welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between 17-4PH stainless steel and Ti6Al4V alloy. For this purpose, the welding of these two alloys was performed with an copper interlayer with a thickness of 1 mm. Two different welding speeds of 0.7 and 0.9 m/min with four levels of beam offset (0, 0.2, 0.4 and 0.6 mm) from the center of the interlayer towards the steel were used to accomplish the experiments. The results show that by using the copper interlayer with thickness of 1 mm, the cracks caused by the formation of intermetallic compounds are removed from the weld pool. At the interface between the titanium and the weld pool, at the beam offset of 0 and 0.2 mm, a solid solution of copper and TiCu 2 intermetallic compounds is formed, while at the beam offset of 0.4 and 0.6 mm, a solid solution of copper and TiCu intermetallic compounds is formed. The weld pool, at the beam offset of 0 and 0.2 mm, consists of TiCr 2 +TiFe 2 intermetallic compounds while at the beam offset of 0.4 and 0.6 mm, solid solution of iron (α-Fe), solid solution of copper and TiCu intermetallic compounds are formed. The highest value of hardness is observed at the interface between the weld pool and the titanium alloy, as well as at the interface between the weld pool and the steel, which is due to the presence of intermetallic compounds with high hardness in these regions. By increasing the welding speed and the beam offset, the hardness value decreases, which is due to the reduction of brittle intermetallic compounds in the joint structure. By increasing the beam offset from 0.4 mm to 0.6 mm at the speed of 0.7 m/min, the shear strength increases from 180 MPa to 210 MPa and at the speed of 0.9 m/min, the shear strength raises from 230 MPa to 250 MPa. The welded sample with the welding speed of 0.9 m/min and the beam offset of 0.6 mm has the highest shear strength equal to 250 MPa. The failure in all samples happened at the interface between the weld pool and the titanium alloy, which shows that the weakest region in the joint is this interface.
Optimization of Stir Friction Welding parameters such as linear and rotational speed of the tool ... more Optimization of Stir Friction Welding parameters such as linear and rotational speed of the tool can be effective to a large extent in improving welding properties. In this research, welding of two sheets of Aluminum of Al-7075 and Al-6061 were validated based on theoretical relations and numerical simulation. The simulation of the contact characteristics of the workpieces with the tool was done using the contact algorithms available in the Ansys software. From the FEM, rotational and linear speed and diameter of the tool were selected as design variables, and multi object optimization was carried out with genetic algorithm and RSM to reach the lowest tool temperature and residual stress.The parametric analysis of FSW of the threaded and non-threaded tool pins showed that the generated heat has proportional and inverse relation with rotation and linear speed of tool respectively. Tool with a diameter of 20 mm showed minimum residual stress in the workpiece. By increasing welding speed, the temperature curves become more compact and the effect of thread on heat generation was more evident in all cases at lower heat input.
Joining of Hastelloy C276 nickel-base superalloy to AISI316 Stainless Steel using BNi-2 interlaye... more Joining of Hastelloy C276 nickel-base superalloy to AISI316 Stainless Steel using BNi-2 interlayer performed by transient liquid phase process (TLP) at 1150°C for 5 and 30 minutes. Bonding microstructure was studied using an Optical microscope and a scanning electron microscope (SEM). Vickers hardness test and shear strength test have been used to evaluate the mechanical properties. Microstructural studies showed that at 5 and 30 minutes of bonding time, isothermal solidification is completely formed, and the Center of the joint is free of any eutectic intermetallic compounds. Also, Findings showed that the DAZ of Hastelloy C276 nickel-base superalloy contains rich borides of Ni, Cr, Mo, and W, and the DAZ of 316 austenitic stainless steel contains borides rich in Fe, Cr, and Ni.
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articles by Journal of Welding Science and Technology of Iran (JWSTI)