Comparative analysis on microstructure and mechanical properties of P92 steel welded joints by pulsed arc welding and GTAW-SMAW welding process

Objective The influence of pulsed arc welding on microstructure and mechanical properties of P92 steel welded joint was investigated, and explored the reliability of pulsed arc welding improved mechanical properties of P92 steel welded joint. Methods The welded joint samples of P92 steel were produced by pulsed arc welding process and GTAW-SMAW process. The microstructures, microhardness, room temperature and high temperature tensile properties and creep rupture property of the welded joints were tested and analyzed. Results The results showed that the microstructure of weld and HAZ of pulsed arc welding joint was finer than that of GTAW-SMAW welded joint. The area of HAZ in pulsed arc welding joint was narrower than that in GTAW-SMAW welded joint. No obvious overheated coarse-grained HAZ was observed in the pulsed arc welding joint, but the micro-hardness results showed that the area near the fusion line exhibited an overheated hardening zone. The tensile properties of pulsed arc welding joint at room temperature were similar to those of the GTAW-SMAW welded joint, while the tensile properties at high temperature were slightly better than those of GTAW-SMAW welded joint. The creep rupture life of the pulsed arc welding joint at 650 ℃ and 100 MPa was similar to that of the GTAW-SMAW joint, which can be attributed to the similar width of the softening zone of the heat affected zone in two kinds of welded joints, because the microstructure and mechanical properties of the softening zone determined the creep rupture life of the whole welded joints. Conclusion By comparing the microstructure and mechanical properties of P92 steel welded joint with two welding methods, it proved that pulsed arc welding could be used as an alternative method for P92 steel welding.