All-positional flux cored wire with lower trace element contents and improved ambient temperature toughness for welding P91 steels

Abstract

The productivity benefits of utilizing flux cored wire for welding P91 steels have been recognized for many years. However, due to the moderate ambient temperature impact toughness and relatively high level of the Bruscato factor (X-factor) of the weld metal from the flux cored wire consumables, the application range of the FCAW in welding P91 steels has been limited when compared with other processes, e.g., GTAW, SMAW, and SAW. Consequently, the development for continuous improvement of the P91 flux cored wire has been an active area. Efforts have been focused on optimizing weld chemical composition to control the levels of trace elements and improve the impact toughness. The present paper introduces the latest advances achieved in the improvement of a rutile-based all-position flux cored wire for P91 steels. The progress has resulted in an optimized weld metal chemical composition with a substantially lower X-factor, better mechanical properties with significantly improved impact toughness at ambient temperature, and further enhanced out of position welding performance.