Room temperature tensile test and the stress rupture test at 975 ℃/196 MPa were conducted in K424 alloy after solution treatment at different conditions(1200-1240 ℃ x4 h,air cooling).The results show that the uniform fine γ'precipitates with high cubicity are reprecipitated in the K424 alloy after completely solution treatment at 1220,1230 and 1240℃.The room temperature strength and plasticity of the K424 alloy after complete solution treatment at 1220-1240 ℃ for 4 h are slightly lower than that of incomplete solution treatment at 1200-1210 ℃ for 4 h,but the stress rupture life is higher.K424 alloy performs the highest stress rupture life(97.8 h)after treatment treatment at 1220 ℃ for 4 h,which is the optimal solution treatment process.The intragranular dislocation and grain boundary are nailed by irregular big γ'precipitates,which are responsible for the improvement of room temperature strength and plasticity of the K424 alloy after incomplete solution treatment.The higher mismatch,cubicity and γ'phase volume fraction,as well as the dissolved γ/γ'eutectics are responsible for the highest stress rupture life of the K424 alloy after complete solution treatment at 1220 ℃ for 4 h.
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