Effect of Post weld Heat Treatment and Filler metals on Microstructures and Mechanical Properties of GTAW and SMAW Weldments between P11 and P91 Steels

The aim of this work is to conduct an optimized conditions of the post weld heat treatment of the GTAW(gas tungsten arc welding) and SMAW (shielded metal arc welding) weld joint between P11 (1.1 Cr) and P91 (8.5 Cr) steels; using E9018B3/ER90SB and E9015B9/ER90SB9 as filler metals. The post weld heat treatment was conducted at 750°C for holding times 0.5, 1 and 2 hours for the evolution of the microstructure, hardness and Tensile Strength ; required for high mechanical performance; at elevated temperatures. The investigated results showed that: the optimum conditions of the post weld heat treatment is 750°C for 1 hour with E9018B3/ER90SB as a filler metal and post weld heat treatment at 750°C for 0.5 hour with E9015B9/ER90SB9 as a filler metal are the proper conditions to reduce the hardness of heat affected zone (HAZ) of P91 steel and regular Hardness distribution.