Effects of Zr Addition Amount on Microstructure and Properties of K465 Superalloy

K465 nickel-based superalloy with different addition amounts (0, 0.005%, 0.025%, 0.050%, mass fraction) of Zr was prepared by vacuum induction melting, and then was subjected to heat treatment at 1 210 ℃ for 4 h. The effect of Zr addition amount on the microstructure, tensile properties, and high-temperature endurance property of the alloy was studied. The results show that block-shaped MC carbides, strip-shaped and granular M₆C carbides, as well as γ/γ' eutectic and microporosity existed in the alloy with different Zr addition amounts. When the addition amount of Zr was not greater than 0.025%, with the increase of Zr addition amount, the content of granular carbides remained basically stable first and then increased, the content of block- and strip- shaped carbides, γ/γ' eutectic and microporosity showed no significant change. When the addition amount of Zr increased to 0.050%, the content of strip-shaped and granular carbides sharply decreased, and the content of block-shaped carbide, γ/γ' eutectic and microporosity significantly increased. With the increase of Zr addition amount, the tensile strength of the test alloy at room temperature showed no significant change, the percentage elongation after fracture remained basically stable first and then decreased, and the endurance rupture time at 975 ℃/225 MPa was prolonged first and then shortened. The optimal addition amount of Zr was 0.025%; the endurance rupture time of the alloy was the longest, which was 70 h, the tensile strength at room temperature was 1 020 MPa, and the percentage elongation after fracture was 9%.