Microstructural Characterization and Mechanical Properties of TIG-Welded API 5L X60 HSLA Steel and AISI 310S Stainless Steel Dissimilar Joints

Dissimilar joining of API 5L X60 ferritic HSLA steel and AISI 310S austenitic stainless steel was conducted by tungsten inert gas (TIG) welding process using ERNiCr-3, ER310, ER2209, and ER309L filler metals. Microstructural characteristics and mechanical properties of the weldments were studied using optical and scanning electron microscopy, ferritometry, microhardness, tensile, and impact tests. The microstructure investigations revealed macro-segregation occurrence and formation of Type II boundaries at the interface of welds with API 5L X60 steel. In tension tests, the joints prepared by ER2209 filler metal showed the maximum yield and ultimate tensile strength values, and the failures were always obtained at the side of API 5L X60. The results of Charpy impact tests indicated that the maximum fracture energy is related to the weld made by ER2209 filler metal. At last, it was concluded that for the dissimilar welding between API 5L X60 and AISI 310S, the weld metal prepared by ER2209 duplex stainless steel filler metal offers the optimum properties at room temperature.