Investigating mechanical properties of laser beam weld seams with LTT-effect in 1.4307 and S235JR by tensile test and DIC
Maximilian Gamerdinger, Fatma Akyel, Simon Olschok, Uwe Reisgen
Abstract
The formation of residual stresses during welding due to the inhomogeneous temperature distribution cannot be avoided. In literature, special low transformation temperature (LTT) filler wires have been developed to control the residual stresses by a martensitic phase transformation. However, in this work, the LTT-effect is achieved by in situ alloying of dissimilar conventional filler wires with the base material thus avoiding a custom fabrication of an LTT wire. The LTT-effect was obtained in two different material combinations. A low alloy S235JR base material was welded with a high alloy G19 9 filler wire as well as a high alloy 1.4307 base material with a low alloy G3Si1 filler wire. Evidence of martensitic weld structure was investigated by etching, hardness measurements and chemical composition. The mechanical properties were investigated by tensile tests and digital image correlation. Both alloys fractured in the base material, indicating an overmatching weld joint.