Effect of welding parameters on the properties of the Ti-6Al-4V plate resistance spot weld joint

Abstract

Titanium alloy Ti-6Al-4V properties advantage gives it a well-known reputation for decades as a reliably material used in a wide range and specific application of resistance spot welded joint such as automotive & aviation products. High strength joint is created depends on the welding parameters used in resistance spot welding. Particular problems occurred about the effect of welding parameters on pure titanium and titanium alloy mechanical and physical properties from previous researches. Some pores and acicular α’ phase appeared in the microstructure, which caused partial interfacial failure mode in the tensile testing. This study is conducted to study the influence of welding parameters for Ti-6Al-4V weld nugget mechanical and physical properties and discover its optimum level of parameters. Tensile-shear testing is used to observed the optimum level. In the optimum level microstructure result reveals that in the weld nugget zone as a fusion zone the lamellar α+β is dominantly observed, this contrasts sharply with the base metal and the heat-affected zone where the primary α and β phase appear to be more dominant. The highest hardness value is discovered in the weld nugget area near the center proving the contribution of the lamellar α+β on this area.

Exploring Resistance Spot Welding for Grade 2 Titanium Alloy: Experimental Investigation and Artificial Neural Network Modeling

“…This allows producing the new lamellar structure of the α and β phases. Therefore, increasing the hardness of the weld nugget zone, and the more lamellar structure that is formed, the more the hardness of the weld nugget increased [6].…”

“…The faster cooling rate in the base metal causes the growth of α and β phase boundaries to be perpendicular to the lamellar and appear nucleated [6]. Because of that, the new lamellar structure does not form in the microstructure, particularly in the base metal.…”

“…Around 90% of all vehicle body assemblies use resistance spot welds [5]. For example, an average automobile includes more than three thousand spot welds [6]. In the case of bus and coach bodies, this figure may rise to as many as 8000 spots.…”

“…Online inspection verified the presence of splashes and imperfect welding fusion. Fatmahardi et al [6] found that the fractured surface of RSW for Ti-6Al-4V was cup-andcone pull-out failure, proving that the weld nugget is stronger than the heat-affected zone (HAZ) and base metal. Dissimilar micro-RSW of austenitic stainless steel 316L and Ti-6Al-4V titanium alloy was studied by Mansor et al [22].…”