Microstructure and mechanical properties of tungsten inert gas welded–brazed Mg/Ti lap joints

Abstract

The tungsten inert gas (TIG) welding-brazing technology using Mg based filler was developed to join AZ31B Mg alloy to TA2 pure Ti in a lap configuration. The results indicate that robust joints can be obtained with welding current in the range of 60-70 A and welding speed of 0?2 m min 21 . The joints were found to be composed of the coarse grained fusion zone accompanied with the precipitated phase of Mg 17 Al 12 , and a distributed Mg-Ti solid solution zone at the interface of Mg/ Ti, indicating that metallurgical bonding was achieved. The maximum tensile-shear strength of 193?5 N mm 21 , representing 82?3% joint efficiency relative to the Mg alloy base metal, was attained. The optimised Mg/Ti joint fractured at Mg fusion zone upon tensile-shear loading, mainly caused by grain coarsening. Moreover, the fracture surface practically consisted of scraggly areas, which was characterised by equiaxed dimple patterns accompanied with a few lamellar tearing.

Microstructure and mechanical properties of Al/Ti joints welded by resistance spot welding

“…Lv et al have proposed a novel TIG welding process called keyhole arc weldingbrazing that was used to join Ti-6Al-4V and 5A06 Al. 11 Wan et al have joined aluminised Ti-6Al-4V and 5A06 Al and found that the ability of liquid filler metal to spread on the Ti substrate was significantly enhanced by 1 the presence of an aluminised coating. 12 Cao et al have used low heat input to restrict the formation of Al/Ti IMCs during cold metal transfer welding-brazing.…”

Study on microstructure and properties of resistance spot welding of Mg/Ti dissimilar materials

“…However, in the process of non-uniform cooling, the coarse grain appeared, accompanied by the precipitated phase of Mg 17 Al 12 in the fusion zone. In addition, the maximum tensile-shear strength of 193.5 N/mm, which represents 82.3% joint efficiency relative to the Mg alloy base metal, was attained [11]. Gao studied dissimilar Ti/Mg alloy butt welding by fibre laser with Mg filler wire-preliminary, observing some flake or a granular mixture of α-Ti, α-Mg and Mg 17 Al 12 in the fusion zone [12].…”

Kinetics of joint formation during diffusion induced solid state bonding of titanium and magnesium alloys

“…Fusion welding process is the method used for joining similar metals. However, the application of any fusion welding technique to join dissimilar metals presents additional difficulties, the first one being; the reaction of the two metals at the joint interface can create compounds that may have unfavourable properties [9] [10]. Another limitation to the use of these alloys includes galvanic corrosion due to differences in electrode potential values between the materials.…”

“…The method has been shown to promote joining by removing surface oxide and ensuring metal-to-metal contact. Sheng et al [9] created a Ti/Mg lap joint using tungsten inert gas welding [13] [14]. Joint formation and the strength developed in diffusion bonds have been shown to relate to the width of the reaction layer formed at the interface during joining.…”