Microstructure and Mechanical Properties of Friction Stir Welded 430 Stainless Steel

This paper investigates the effect of friction stir welding (FSW) speed on the microstructure and mechanical properties of 430 ferritic stainless steel. Stainless steel sheets with 2 mm thickness were welded by FSW. A WC-base tool was used at different welding speeds of 150, 200, and 250 mm/min. The microstructure and mechanical properties examination were conducted by optical microscopy, microhardness, and tensile tests. The microstructural observation showed that the structure in the stir zones of the welds is too refined, and the average grain size is decreased from 29 to 1-2 μm. An increase in welding speed results in a slightly grain refining of SZ, due to a decrease in weld heat input. The microhardness profile revealed the maximum hardness of SZ in compare with other weld area. In addition, the tensile tests showed that in all welding speeds, except 250 mm/min, the fracture occurred in the base metals.

Keywords:

Friction stir welding (FSW) , Ferritic stainless steel , Microstructure , Mechanical properties