Microstructure Evolution and Mechanical Properties of Dissimilar Welded Joint of P911 and P92 Steel for Subsequent PWHT and N&T Treatment

Abstract

Over the past years, the alloy development has led to the development of new steels such as P91 (X10CrMoVNb9-1), P911 (X11CrMoWVNb9-1-1), and P92 (9Cr–0.5Mo–1.8W–V–Nb). The topic of the present research work was selected to concentrate on the dissimilar welding of P911 and P92 steels by using manual metal arc welding (MMAW) to work on the weldability with pre and post weld heat treatments. The welding procedure for components of 9–12% Cr steels was related to three main aspects: the materials, the process used for welding and the type of components used to weld these steels. MMAW process was applied to produce the dissimilar joint of the P911 and P92 steel by using E-911 electrode. Normalizing and tempering (N&T) and post-weld heat treatment (PWHT) were applied to the welded plates of thickness 12 mm and they were tested using tensile test, hardness test, Charpy toughness test, and microstructural investigations. During the room temperature tensile tests, serrations were also observed. PWHT of weldments resulted in a negligible increase in ultimate tensile strength and yield strength while a significant change was measured after N&T. The N&T condition resulted in minimum hardness gradient and maximum homogenization of microstructure across the dissimilar weldments. The room temperature Charpy toughness value was also found to be maximum for N&T treatment.