Microhardness analysis in MIG welding of stainless steel 409M

Abstract

Stainless steel 409M is a utility grade ferritic steel and was developed as a cheaper alternative to Austenitic stainless steel as it has less amounts of Ni, but still posses very good corrosion resistance, mechanical properties and weldability. In the present investigation, effect of heat input and cooling rates on the magnitude and distribution of microhardness values in different weld zones developed during the MIG welding of this material have been studied and analyzed. A weld can broadly be divided into four main zones namely; fusion zone (FZ), weld interface or fusion boundary zone (FBZ), heat affected zone (HAZ) and unaffected base metal zone. These zones experience different rates of cooling, resulting in the formation of different microstructures. Microhardness study is one of the methods of testing the quality of a weld as it enables the mechanical properties to be determined in different weld zones by corroborating the nature of microstructure constituents present therein.