Joining of dissimilar AZ31B magnesium alloy and SS400 mild steel by hybrid gas tungsten arc friction stir welding
TL;DR: In this paper, a hybrid gas tungsten arc-friction stir welding (HGTAFSW) method was used for the joining of dissimilar materials, magnesium alloy (AZ31B) and mild steel (SS400), and compared to those of FS welds to confirm the effect of the additional GTAW preheating heat source.
Abstract: The joining of dissimilar materials, magnesium alloy (AZ31B) and mild steel (SS400), was performed using a hybrid gas tungsten arc-friction stir welding (HGTAFSW) method that applied a preceding gas tungsten arc welding (GTAW) preheating heat source to a mild steel plate surface during friction stir welding (FSW). The mechanical and microstructural characteristics of the HGTAFS welds were evaluated and compared to those of FS welds to confirm the effect of the additional GTAW preheating heat source. The tensile strength of the HGTAFS welds was approximately 91% of that of the magnesium alloy base metal but higher than that of the FS welds. This was attributed to the enhanced material plastic flow and partial annealing effect in the magnesium alloy and mild steel materials by GTAW reheating of the mild steel side, which induced a significant increase in the elongation of the welds. The concentration profiles indicated that no intermetallic FeAl and FeAl3 compounds had formed according to the phase diagram, which led to a decrease in joint strength. Overall, the use of HGTAFSW by applying a GTAW preheating heat source to a mild steelplate surface resulted in a mechanically sounder and metallurgically defect-free welds compared to FSW.
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TL;DR: Heating assisted friction stir welding (FSW) was carried out at different preheating currents of 40, 80 and 120 amps by applying tungsten inert gas torch ahead of stirring tool while, compressed air and water were brought into the effect behind the stirring tool as mentioned in this paper.
90 citations
TL;DR: In this paper, the main process variables were measured, characterized and compared in friction stir welding with/without ultrasonic vibration, and the ultrasonic vibrations improved weld formation by either reducing or eliminating the weld defects.
87 citations
25 Mar 2015-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of annealing and secondary rolling process has been investigated in relation to evolution of interface microstructure as well as interfacial bonding mechanisms of roll-bonded two-ply Mg/Al clad sheets.
Abstract: The effect of annealing and secondary rolling process has been investigated in relation to evolution of interface microstructure as well as interfacial bonding mechanisms of roll-bonded two-ply Mg/Al clad sheets in this study. Two types of thin reaction layers, viz., γ (Mg17Al12) and β (Mg2Al3) phase layers, were observed to form along the Mg/Al interface, the thickness of which was found to increase with annealing time. The grains in the γ layer were grown coarsely in a columnar shape, as they grew continuously in coarse-grained Mg substrate alloy side. The thickness of the γ layer was found to reduce significantly after the secondary one-pass rolling. At the same time, the initially columnar γ grains became refined into equi-axed grains by recrystallization caused by large plastic deformation during the secondary rolling. The serrated flow observed in the reaction layers during a nano-indentation test in the γ layer disappeared completely without any sign of micro-cracks after the secondary rolling. This in turn implies that the γ layer, acted as an embrittlement site before the rolling, may not be brittle any longer after the rolling. The grain refinement and disappearance of columnar grains in the γ layer appear to greatly improve the interfacial bonding strength in these clad sheets. This secondary rolling process seems to provide a great advantage in terms of manufacturing, since the same rolling stand for roll-bonding process can also be used without any additional equipment.
77 citations
TL;DR: The state-of-the-art, experimentation and progresses in these FSW variants are surveyed and compiled in this paper, where the auxiliary energy assisted FSW processes exhibit great promise by having numerous advantages over the conventional FSW in terms improved process window, heat generation, material flow, reduced load on the tools and mechanical properties of joints.
Abstract: The present article introduces the auxiliary energy assisted friction stir welding (FSW) processes purported to overcome the shortcomings of the conventional FSW process. The auxiliary energies used for this purpose are thermal energy from electric resistance heat, induction heat, laser, plasma, arc, etc. and mechanical energy in the form of ultrasonic vibration. The state-of-the-art, experimentation and progresses in these FSW variants are surveyed and compiled. The auxiliary energy assisted FSW processes exhibit great promise by having numerous advantages over the conventional FSW in terms improved process window, heat generation, material flow, reduced load on the tools and mechanical properties of joints. Such remarkable advantages would lead these processes to redefine many global technologies and markets in the twenty-first century. However, these variants are still in their preliminary stages of investigation, and more systematic investigations are necessary for their critical assessment. I...
75 citations
Cites methods from "Joining of dissimilar AZ31B magnesi..."
...The TIG arc integrated FSW (TIGFSW) has been employed mainly in the dissimilar welding of softer and harder alloys, such as Al6061T6+STS304 stainless steel,(72) Al6061-T6+Ti–6Al–4V titanium alloy(73) and AZ31B magnesium alloy+SS400 mild steel.(74) The total heat input in the AAFSW is obviously higher than that in the conventional FSW; the high heat input brings down the mechanical strength of workpieces and causes softening of material to favour plastic deformation and material flow....
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TL;DR: In this article, a differential-speed rolling (DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473, 523, 573, and 623 K with 1-pass and 2-pass operations.
69 citations
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TL;DR: In this article, the joining of dissimilar Al 6013-T4 alloy and X5CrNi18-10 stainless steel was carried out using friction stir welding (FSR) technique.
389 citations
TL;DR: In this article, the postweld properties of dissimilar friction stir welds of mild steel/A7075-T6 aluminum alloy were investigated and the joint strength increased with reduction in thickness of the intermetallic compound at the weld interface.
279 citations
TL;DR: In this article, a tool was significantly worn during welding and was broken after traveling 100 mm at a rotational speed of 917 rpm, and the tool breakage was detected by the incorporated acoustic emission (AE) sensors.
Abstract: The joining of a 6-mm thickness Al 6061 to AISI 1018 steel has been performed by the combined effects of fusion and solid state welding. The process is derived from friction stir welding (FSW) but with an adjustable offset of the probe location with respect to the butt line. Metallographic studies by optical microscopy, electron probe microscopy, and the utilization of the X-ray diffraction technique have been conducted. It was found that the intermetallic phases Al13Fe4 and Al5Fe2 exist in the weld zone. The tool was significantly worn during welding and is broken after traveling 100 mm at a rotational speed of 917 rpm. The wear of the tool significantly affects the structure of the weld, and the tool breakage was detected by the incorporated acoustic emission (AE) sensors. It appears that the joining of an Al 6061 alloy to AISI 1018 steel with a sound heterogeneous weld microstructure is feasible using this process, and the tool breakage can be detected by the AE sensing technique.
252 citations
TL;DR: The mechanical and metallurgical properties of friction welded joints between type 5052 aluminium alloy and type A36 steel have been studied in this article, where a very fine and equiaxed grain structure was observed near the interface.
Abstract: The mechanical and metallurgical properties of friction welded joints between type 5052 aluminium alloy and type A36 steel have been studied in the present work. Joint strength increased with increasing upset pressure and friction time until it reached a crictical value. The strength of the joint settled at a lower value, compared with that of the base metal, in the case of increasing friction time, caused by the formation of an intermediate phase (intermetallic compound, oxides). The microstructure of 5052 alloy was greatly deformed near the weld interface, and underwent dynamic recrystallisation owing to frictional heat and deformation resulting from the friction welding process. Therefore, a very fine and equiaxed grain structure was observed near the interface. Elongated grains were observed outside the dynamic recrystallisation region at the peripheral part, while the A36 steel side was not deformed. The hardness of the near interface was slightly softer than that of the 5052 alloy base metal...
74 citations
TL;DR: In this paper, the formability of laser assisted friction stir welded steel aluminium joints was evaluated by applying tensile tests to achieve mechanical properties of joints, which were welded by systematic variation of process parameters.
Abstract: Steel aluminium Tailor Welded Hybrids are still mentioned to be difficult to be joint as intermetallic phases appear during melting welding techniques. These phases are the reason for failure of the joint during loading or forming. As conventional friction stir welding, a solid phase welding technology, is not feasible to join steel and aluminium, laser assistance for preheating the steel sheet is adapted in order to enhance the weldability as well as the welding feed and to reduce the wear at the tool. Tensile tests are performed to achieve mechanical properties of joints, which were welded by systematic variation of process parameters. Finally deep drawing tests are conducted to demonstrate the formability of laser assisted friction stir welded steel aluminium joints.
60 citations