A Brief Study on the Heterogeneity of the P91 Welded Joint

The gradient microstructure occurs along with the P91 steel pipe welds joint which has been characterized in detail. The welding thermal cycle results in variation in mechanical behavior along the welded joint that leads the degradation in the mechanical performance of the welded joint at elevated service temperature in power plants. The gas tungsten arc welded (GTAW) joint has been subjected to as-welded and heat treatment conditions to study the role of heterogeneity on microstructure across the welded joint and the mechanical properties. The P91 welded joints have been subjected to tempering at 760 °C for 2 h (HT1) and post-weld normalizing and tempering (HT2). The precipitation hardening, quenching stress in welded joint and martensite softening are mainly associated with heat treatment. A negligible variation in hardness and microstructure has been observed across the welded joint for HT2 treatment.