Reducing diffusible hydrogen contents of shielded metal arc welds through addition of flux-oxidizing ingedients

This investigation examined the feasibility of using flux modification in the form of the addition of oxidizing ingredients to reduce the as-deposited hydrogen content of basic-type shielded metal arc welds. Additions of up to 16.3% micaceous iron oxide (MIO) to the flux formulation of an E7018-1 type electrode lowered the diffusible weld hydrogen content by approximately 70%. This can be attributed to the formation of oxygen, which lowers the partial pressure of hydrogen in the arc atmosphere, and the reaction of FeO (formed on dissociation of MIO) with hydrogen. The partitioning of deoxidizing elements (manganese and silicon) between the weld metal and slag on addition of MIO to the flux coating was also examined, but the influence of flux additions on the weld mechanical properties and the electrode operating characteristics was not evaluated during the course of this investigation.