Comparative Evaluation of Ni-Based Electrodes for Shielded Metal Arc Dissimilar Welding of P91 and AISI 310 Steels: Microstructure and Mechanical Performance
摘要
The dissimilar welded joint of P91 ferritic/martensitic steel and AISI 310 austenitic stainless steel was fabricated using shielded metal arc welded (SMAW) with three different grades of Ni-based electrodes: Inconel 117 (ENiCrCoMo-1), Inconel 112 (ENiCrMo-3), and Inconel 182 (ENiCrFe-3). The weld metal characterization revealed a typical dendritic austenitic microstructure for all electrode welds, with a high nickel content. The EDS analysis of the weld revealed the presence of Ti(C, N) and NbC in the Inconel 182 electrode weld, NbC and Laves phase in the Inconel 112 electrode weld, and Cr and Mo-rich phases (M23C6 and Mo6C) in the Inconel 117 electrode weld. Room temperature tensile tests showed that all electrode welds were failed in the AISI 310 steel with ultimate tensile strength (UTS) of 580 ± 3 MPa for the Inconel 117 weld, 574 ± 5 MPa for the Inconel 112 weld, and 575 ± 6 MPa for the Inconel 182 weld. During high-temperature tensile testing, a mixed failure region was observed and few samples were failed in the P91 steel, while others failed at the interface in a brittle mode. Among all the electrodes, the Inconel 182 electrode weld exhibited the highest impact strength of 172 ± 12 J, while the lowest impact strength was observed for the Inconel 117 electrode which was 80 ± 10 J. The composition gradient and reheating effects of welding produces a significant variation in hardness both in weld metal and along the welded joint. The maximum hardness was 242 ± 9 HV for the Inconel 112 weld, while the minimum was 205 ± 9 HV for the Inconel 182 weld. Based on microstructural and mechanical behaviour study, the ENiCrFe−3 electrode was selected as the best option among all for obtaining the SMAW joint between P91 steel and AISI 310 steel.