JOURNAL OF WELDING SCIENCE AND TECHNOLOGY OF IRAN
Year:2017 | Volume:3 | Issue:1 |Papers Count:9

The aim of this study is investigation of TLP variables on microstructure and mechanical properties of Al2024 to Ti-6Al-4V bonding for TLP joint. For this purpose, the sheets were prepared with dimension of 130×32×3 mm from Ti-6Al-4V and Al2024 alloys and 50μ m thick Sn-5. 3Ag-4. 2Bi foil as interlayer. Sn-5. 3Ag-4. 2Bi foil prepared with dimension of 32×25 mm. Two alloys was joint together by process of Successive stage Transient Liquid Phase (S-TLP). This process is contains two stages. The first one is Transient Liquid Phase (TLP) of Ti-6Al-4V and the second stage is diffusion bonding of Al2024 to Ti-6Al-4V. In the first stage, TLP process was used for joining of Ti-6Al-4V to Ti-6Al-4V samples. This process carried out under argon gas at 2 atmosphere and at 620 ° C. After the end of first stage, the samples were broken from the joint region and then, the obtained surface was jointed to Al2024 with new interlayer. In the second stage, that is soldering, the samples were placed in furnace under argon gas at 2 atmosphere and at 453 ° C. Maximum tensile strength of diffusion bonding was about 62 Mpa.

In this research, the microstructure and mechanical behavior of dissimilar joint of AISI 321 stainless steel to ASTM A57CL1 were studied. For this purpose, the GTAW process and ER 308L filler metal with diameter of 1. 8 mm were used. In order to study the microstructure and fracture surface of weld samples, optical microscope and scanning electron microscope (SEM) were used. Also, the mechanical behavior of the joint was examined by impact, tension and microhardness tests. It was found that the microstructure of weld metal was austenite with skeletal ferrite. Also in some areas the lacy ferrite was seen. All samples were fractured from ASTM A537CL1 steel with a ductile manner during the tension test. The weld metal indicated high impact energy about 205 J.

In this study, the corrosion behavior of super duplex stainless steel UNS S32750 and tungsten arc welding with filler metals AWS ER2594 duplex stainless steel in acidic solution containing chloride ions have been investigated. Microstructure of weld joints evaluateby light and electron microscope and corrosion behavior examine by open circuit potential and cyclic polarization tests. The results showed that increas in heat input leads to a change in the distribution of alloying elements, formation of intermetallic phases around grain boundaries and the shifting balance between austenite and ferritein phases in weld region. Based on the cyclic polarization tests, cross-weld and base metal active behavior and have good corrosion resistance due to the presence of high alloying elements. As well as increase in heat input leads to an increase in current density and decrease in the pitting potential.

In this study, the effects of linear speed and rotational speed of the friction stir welding tool was investigated on the heat generation and distribution of heat, the material flow and weld defect formation of the Polyamide 6 (PA6) workpiece. The commercial CFD Fluent 6. 4 software package was used to the simulation of the process with computational fluid dynamic technique. The output results of the simulation showed higher proportion of rotational speed to the tool linear speed, the material flow in front of the friction stir welding tool became more and the dimension of the welding stir zone became bigger. The maximum simulating generated heat was 220 centigrade degrees and the maximum head and material flow were observed at the advancing side of the join surface. The obtained simulation results were compared with other researchers' experimental results and the simulation outputs displayed acceptable agreement with experimental results.

In this study, The Al 6061 alloy sheets were produced by Cryorolling process and then were welded by resistance spot welding method. In this regard, the solution treated Al 6061 alloy cryorolled subsequently up to 90% reduction in thickness to produce nanostructure alloy. The cryorolled sheets were then subjected to aging treatment (130˚ C-30h) in order to obtain simultaneous strength and ductility. Tensile strength of 370 MPa, hardness of 135 HV, and ductility of 11 % was obtained for the nanostructured Aluminum sheets. The Cryorolled samples were then resistance spot welded with different welding parameters, including welding current 50 to 100 kA, electrode force of 2. 8 kN, and welding time of 0. 1 s. The most tensile shear peak load of weld spot of nanostructured samples was 5580 N. The results for different welded samples showed that the nanostructured ones, have higher weld strength when compared with 6061-T6 Aluminum alloy samples with common grain size.

In this paper, laser beam welding of a rectangular piece of steel was simulated using Fluent software. Physical properties of analytical field was constant and its changes with temperature was ignored. In the present work, effect of tool speed and laser power on temperature distribution of workpiece surface and different deeps in the plane of symmetry and also maximum of temperature and depth of penetration were investigated. Using a macro code, geometry generation and meshing of the analytical field by helping required geometric parameters were provided for software. Moreover, laser radiation power was exerted by writing an UDF in the fluent software. In this case, it was assumed that the workpiece is stationary and gaussian thermal source model defined in UDF moves with the intended speed. Results show that at a constant power, maximum temperature of the workpiece decreases with increasing heat source speed, moreover, in this case, gradient of temperature in front of the workpiece and behind of it, increases and decreases respectively. It is found that the temperature in the depth of the workpiece increases with increasing the power.

Nowdays, the prediction and prevention of fatigue failures is converted to one of the most concerns for industry owners. Since the processes of fatigue suddenly occur, it is most important and necessary to recognize the effective factors of fatigue life of structures. Mechanical and thermal multiple loading are the important factors of the fatigue failure. In order to appropriate fatigue design, analysis should be validated with experimental results. In present research, fatigue life of A36 welded steel samples obtained from test is compared by finite element results obtained from commercial ansys pakage. In this research, the effects of residual stress, reinforcement, notch and thickness of sampels on fatigue life are studied. Results of analytical simulation and experimental show good agreement. Results also shows the dominant effect of reinforcement on the fatigue life.

A517 is a low alloy high-strength steels that due to its high strength, toughness and weldability is used in ship building and submarine hulks. The welded areas of this steel often require repairs. In this study, the effect of number of welding repair on microstructure and mechanical properties of A517 steel is studied. Four samples (samples without repair, once repaired, twice repaired, and three times repaired) were welded by SMAW welding. Microstructural studies were carried out by using optical and scanning electron (SEM) microscopes. The effect of the number of repairs on mechanical properties of samples were investigated by using tensile, bending, impact and hardness The profile of hardness illustrated that the hardness in the heat affected zone near the base metal increased by repeated repairs while the hardness of this zone reduced in the third repaired sample. By repeating the welding repair, tensile and yield strengths of the welding areas were reduced and fracture impact toughness of heat affected zone at-51○ C was increased. Generally, the results of tensile tests of second and third repaired indicated that the strength of these samples were not meet the ASME IX standard requirements, so welding steel A517 in the second and third repairs is not acceptable.

Aluminum to stainless steel joints are broadly used in industries in order to reduce fuel consumption. While fusion welding is not a suitable method to join these metals. solid state welding, like friction welding (FW), is an effective way to this process. However, risk of intermetallic compounds (IMCs) formation is probable in these welds. In previews investigations formation of FeAl3, Fe2Al5 and Fe4Al13 is reported. In this study, effect of different parameters on generated heat and temperature distribution that lead to formation of these compounds in a FW of aluminum alloy to stainless steel is investigated using Finite Element Method (FEM). Additionally, a mathematical modeling of the parameters is performed using Artificial Neural Network (ANN) and the optimum level of the parameters has been found.