Harm of sulfur in Ni-base superalloys and desulfurization in electroslag remelting process

In the Ni-based superalloys,sulfur segregation at the grain-boundary and the surface can easily reduce alloy lasting life and working stability at high temperature.To further reduce sulfur in the Ni-base superalloy,three ESR experiments were conducted for desulfurization of GH4169.The results indicated that the efficiency of desulfurization of ESR was obvious,sulfur contents were reduced from 18 ppm in electrodes to 6 ppm in ingots and the sulfur content in slag did not increase;desulfurization ratios of PESR were influenced by sulfur accumulating in slag,sulfur contents in ingot increased from 7 ppm to 9 ppm.For PESR with Ca added in slag,desulfurization was improved greatly,sulfur content decreased with the calcium increment in the ingot.Finally,sulfur content reduced to 3 ppm.Relationship between w and w[S] in the alloy was in agreement with thermodynamic calculation results.