Influencing factors on weld-seam toughness and its discreteness of self shielded flux cored wire

The toughening mechanism of the weld metal by self shielded flux cored wire was introduced, the influence of alloy elements, inclusion and rare earth element on weld-seam toughness were analyzed. And the results indicated that coarse M-A structures in weld-seam caused the discreteness of weld toughness. The wire with proper chemical composition and appropriate thermal input were used, M-A structures can be reduced and refined and the toughness will become stable.