Weld solidification behavior of Superaustenitic Stainless Steel and Ni-base alloys

Super-Austenitic Stainless Steel (SASS) is an advanced class of high alloy materials whose excellent corrosion resistance provides significant advantage in engineering applications in aggressive environments. However, conventional arc welds prepared on SASS alloys are vulnerable to accelerated corrosion due to the microsegregation of strategic alloying elements. Laser materials processing provides a unique opportunity to improve the corrosion performance of SASS welds by potentially producing segregation-free microstructures with extended solubility of alloying elements. In addition, laser welds can be produced without the need for high alloy Ni-base filler metals, thereby significantly reducing cost in manufacturing applications. The overall objective of the research discussed here is to develop a solidification model of the laser welding process on superaustenitic stainless steel alloys in order to optimize the mechanical and corrosive performance of the weld material. The work presented in this paper represents a fundamental study of the solidification behavior of SASS and Ni-base alloys, thereby providing a baseline for comparison when the more complicated material behavior under rapid solidification conditions in laser welds is analyzed. Hence, the effectiveness of laser welding parameters in controlling the microstructure and performance of the welds can be evaluated, providing direct practical information for industrial applications.