Abstract: 0.020, 0.045 and 0.075 wt pct Zr were added to a Ni-base superalloy GH586 to investigate their effects on the microstructure and the short-term strengths at 850℃. The results showed that proper Zr addition could improve the alloy tensile strength at 850℃and short-term rupture life at 850℃, 580 MPa. Zr exists in both γ' phase and γ matrix, which caused Zr to distribute in grain instead of segregating in grain boundaries, therefore increased both of their lattice parameters but decreased the mismatch between them. Meanwhile, it also increased the amount of grain-boundary carbides and decreased their size markedly. These contributed to the improvement of short-term rupture life. However, further addition of Zr resulted in forming Zr4C2S2, a plate-like stable sulphurocarbides in grain boundaries, which decreased short-term strength at high temperature, and led to a worse hot workability. According to the experimental results, the optimum content of Zr should be 0.020 wt pct.

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