Studies on influence of torch orientation on microstructure, mechanical properties and formability of AA5052 CMT welded blanks

Abstract

Generally, in gas metal arc welding (GMAW) high heat input causes drastic changes in the microstructures of weldment (fusion zone and heat affected zone), which in turns affects the performance of the welded blanks during forming operation. The present study focuses on the parametric effects such as welding current, welding speed and torch orientation concerning welding direction on mechanical properties, microstructural characterization and formability of AA5052 Cold metal transfer (CMT) welded blanks (WB's). Based on the macrostructure images obtained from various trials (trial 19, 20 and 21, which is corresponding to Drag angle of 10°, 90° or Zero angle and Push angle of 10°, respectively) three were selected for further studies. The macrograph, microstructural evaluation, mechanical behavior and forming limit curve (FLC) of the WB's are examined for the selected parameters and for base metal (BM). The formability of the BM and WB's are investigated by obtaining FLC using Nakajima test. Of the three different torch orientation concerning welding direction, the WB made with 10° push angle yields the superior mechanical properties such as high tensile strength, increase in hardness and more bending strength than the remaining torch orientations. In addition, total elongation and formability are of concern; drag angle of 10° yields the better result, compared to the other torch orientations.