Effect of S on Solidification Behavior of Cast Superalloy K417G

The effects of 0.000 1%， 0.001 8% and 0.003 7% S content on the solidification characteristics of K417G alloy were studied by isothermal solidification experiment in the temperature range of 1 340-1 230 ℃. The results show that S can reduce the solidus temperature of the alloy and enlarge the solid-liquid two phase region. When the S content increases from 0.000 1% to 0.003 7%， the solidus temperature of the alloy decreases from 1 255 ℃ to 1 245 ℃. During the solidification process， the S element segregates in the liquid phase and precipitates out as the Y phase in the final solidification zone. And S promotes the enrichment of Al and Cr elements at the solid-liquid interface. At the same isothermal temperature， the increase of S content promotes the increase of the volume fraction of MC carbide， γ+γ΄ eutectic and Y phase， and has little effect on the morphology and precipitation temperature of MC carbide and γ+γ΄ eutectic， but the precipitation temperature of the Y phase is increased from 1 230 ℃ to 1 240 ℃.