Adjustment of chemical composition with dissimilar filler wire in 1.4301 austenitic stainless steel to influence residual stress in laser beam welds

Abstract

Residual stress is a considerable challenge in welding. Due to the local heat input high temperature gradients occur between weld seam and base material, which lead to thermal and transformation induced stress. With targeted alloying in the weld seam the martensitic phase transformation can be shifted to lower temperatures, called Low Transformation Temperature (LTT) effect. This effect uses the volume expansion during the martensitic phase transformation, which counteracts the stress accumulation while cooling of the specimen. In most cases, a flux cored filler wire with a typical alloy composition of 10%-Cr and 10%-Ni is used to exploit the LTT effect. In this paper, however, the aim is to alloy in-situ while combining conventional materials of different types. Combinations of high-alloyed base material (1.4301) with low-alloyed solid filler wire (G3Si1) are analysed. For comparison, similar welds with high-alloyed solid filler wire (G19 9) are also carried out. The chemical compositions are generated within a laser beam welding process and examined by EDS-Analysis. In order to measure the influence of chemical compositions on residual stress, hole drilling measurements are performed. Furthermore, dilatometry tests help to determine the change of phase transformation temperature as well as elongation. EBSD analysis show the changes in phase transformation due to the variation of chemical compositions. It is proven, that a reduction of residual stress by the means of targeted alloying with conventional materials in an austenitic stainless steel is possible.