Microstructure and mechanical properties of the microwave welded dissimilar joints between SS-430 and plain carbon steel

Abstract

Abstract Dissimilar metal joints (DMJs) between low-carbon steel (CS) and ferritic stainless steel (FSS)-430 are required for an assortment of applications, including oil burner parts, storage tanks, and chemical processing equipment. Consequently, there is a high demand in the industry for developing a faster route for the DMJs of FSS-430 and CS. In the present research, the DMJs between FSS-430 and low CS have been carried out in a butt configuration using a hybrid microwave heating (MH) technique with two additive metals: powdered SS-316L alloy and powdered Ni alloy (EWAC-1001). The trials were conducted in an industrial microwave oven operating at 2.45 GHz and 1.2 kW. The fabricated DMJs are further characterized by x-ray diffraction, optical microscopy, scanning electron microscopy, and measurement of Vicker’s microhardness and tensile properties. The phase composition analysis of both DMJs reveals the presence of M 7 C 3 (where M is Cr or/and Fe) and chromium-based carbides (Cr 23 C 6 ) in addition to the main added filler metal. The microstructure of both DMJs was mostly cellular columnar, with the presence of acicular martensite towards the FSS side for the weldment fabricated with EWAC-1001 based filler material. The DMJ’s mean microhardness for the SS-316L and EWAC-1001 added filler materials weldments was determined to be 321 ± 15 HV and 326 ± 25 HV, respectively. The ultimate tensile strength of the weldment fabricated from SS-316L based powder is about 1.06 times that of the EWAC-1001 based samples. From fracture surfaces, it is observed that brittle fracture mainly occurred in the weldment fabricated with EWAC-1001 based alloy powder, while predominantly mixed (ductile and cleavage) fracture happened in the weldment fabricated with SS-316L based alloy powder.