The effects of Silicon and Copper on microstructures, tensile and Charpy properties of weld metals by refined X120 wire

This paper analyzes the micro-mechanism of decrease of impact toughness with increasing Silicon and increasing Copper in weld metal of a low-alloy high-strength X120 steel. By comparing the microstructures, measuring the extending length of the fibrous crack, and calculating the local cleavage fracture stress σf, and then using the basic principles of the micro-mechanism of cleavage fracture, the essential causes of change of toughness in the weld metal of high-strength steel welded joints are revealed in this work.