K465合金的显微组织和性能研究

Study on Microstructure and Properties of K465 Alloy

研究了铸态、热处理态及含0.02%(质量分数)Mg的K465镍基铸造高温合金的显微组织、力学性能.研究结果表明:铸态K465合金组织主要由γ基体、弥散分布的γ′相、(γ+γ′)共晶和碳化物组成,室温平均抗拉强度960MPa,伸长率6.0%,975℃/230MPa条件下平均持久寿命28.1h;经1210℃/4h+空冷的固溶热处理后,晶界MC碳化物部分转变为M6C碳化物,γ′相颗粒尺寸减小到0.1～0.2μm,合金室温平均抗拉强度1055MPa,伸长率4.0%,975℃/230MPa条件下平均持久寿命为50.3h;加入0.02%(质量分数)Mg后,合金中MC碳化物球化,室温平均抗拉强度990MPa,伸长率5.0%,975℃/230MPa条件下平均持久寿命为56.3h.

The as-cast microstructure and properties of K465 nickel-base cast superalloy are investigated, as well as they are during heat-treatment. The results showed that the alloy as-cast is composed of γ phase, γ＇ phase, γ ＋ γ＇） eutectic and MC carbide, and its average tensile strength and percentage elongation at ambient temperature are 960 MPa and 6.0 %, respectively. The creep rupture life under the condition of 975 ℃/230 MPa is 28.1 h. After the 1 210℃/4 h solution treatment followed by air-cooling, the crystal boundary MC carbide partly becomes M6C one with γ＇ phase particle size reduced to 0.1 --0.2μm and the tensile strength and elongation at ambient temperature up to 1 055 MPa and 4.0 %, respectively. The creep rupture life is 50.3 h under the same condition. With 0.02 wt% Mg added in, the grains of MC carbide in the alloy is spheroidized, and the average tensile strength and elongation of the alloy at ambient temperature are 990 MPa and 5.0%, respectively, with a creep rupture life up to 56.3 h under the same conditon.