Cracking behavior and mechanical properties of austenitic stainless steel parts produced by laser metal deposition

The cracking behavior, microstructure and mechanical properties of austenitic stainless steel parts produced by laser metal deposition (LMD) are presented. The existing criteria for evaluating the solidification cracking sensitivity during welding of stainless steels have been adapted. Apart from the presence of sulfur and phosphorous, the presence of silicon was found to have a detrimental effect on cracking resistance. Cracking was not observed if the total content of sulfur, phosphorous and silicon was kept low enough, even not for stainless steels with austenitic solidification mode. Three-dimensional parts produced using optimal process parameters and feedstock powder composition have been investigated in more detail. The parts have a density of 99.6%. The microstructure consists of fine columnar dendrites, which coarsen as a function of height along the building direction. This is accompanied by a decrease in hardness. The tensile strength and elongation are in general higher than for annealed wrought material. The tensile strengths are higher while the elongation is lower for samples loaded perpendicular to the build-up direction than for those loaded parallel.