Mechanical Properties of Laser Welded SS316 and SS321

Abstract

Stainless steel is used in a plenitude of domains from low end applications, like surgical products to high-end applications like aerospace sector. Stainless steels are iron-carbon based alloys with more than 10.5% chromium. The chromium present in stainless steel has greater affinity towards oxygen atom and will result in the formation of chromium oxide film over the surface at molecular level. Stainless steel grades SS321 and SS316 are considered in this work due to its better flexural rigidity, corrosion resistance and maximum temperature withstanding capacity. The laser beam welding was preferred due to high local energy concentration of the laser beam, which makes it more suitable method for stainless steel welding. Chromium precipitation on the grain boundaries is avoided by using a high laser welding speed that diminishes the exposure of the weld to high temperatures. The microstructure of the welded joints are examined using metallurgical microscope to find out the flaws over the weld joint. Three-point bend test was conducted to quantify the mechanical strength of the welded joints.