热处理对一种镍基高温合金组织和持久性能的影响

Influence of Heat Treatment on Microstructure and Stress Rupture Property of Nickel-base Superalloy

研究1220℃×4h固溶+1150℃×4h时效+870℃×24h时效、1220℃×4h固溶+870℃×24h时效和直接进行1100℃×4h三种热处理制度对一种新型镍基高温合金组织和性能的影响。结果表明,这三种热处理制度都能明显提高合金在1100℃/40MPa的持久寿命,分别将其由24h提高到65、64和53 h。合金的组织铸态由γ、γ'以及少量的MC碳化物和M3B2硼化物组成。γ'体积约占58%。合金经过固溶+二级时效的处理,MC碳化物主要以颗粒状分布在晶界。同时γ'分为两种尺寸和形态。经过高温固溶+时效热处理后,发生了MC向M23C6退化的反应,使合金的塑性降低。γ'形状为规则的立方体,且尺寸只有0.4μm。直接1100℃时效也使合金析出两种尺寸和形态的γ',而且使碳化物变得细小。

The influences of three kinds of heat treatment processes on the microstructure and property of nickel-base superalloy were investigated, which are 1220 ℃x4h solution ＋ 1150 ℃x4b aging＋870 ℃x24b aging, 1220 ℃4b solution ＋ 870 ℃ x 24 h aging and 1100 ℃ x 4 h aging. The results show that the heat treatment can improve the stress rupture life at 1100 ℃/40 MPa of the alloy remarkably, the stress rupture life can be enhanced from 24 b to 65, 64, and 53 h respectively. The as-cast microstructure consists of 7, 7＇ and minor MC carbide, M^B2 boride. The volume percent of 3＂ is 58%. After solution and two stage aging, MC presents on grain boundary as small particles. Meanwhile 7＇ has two sizes and morphologies. After the heat treatment of solution and single aging, MC dissociates into M℃6, which degrades the elongation of the alloy. The morphology of y is regular cubic, and is 0.4 μm in size. Two scales and morphologies of precipitate in the alloy if the beat treatment is directly aging, and the size of carbide decreases.