热处理对一种低铼二代单晶高温合金组织和持久性能的影响

Effect of Heat Treatment on Microstructure and Stress Rupture Properties of a Low Rhenium Nickel Base Single Crystal Superalloy

对一种低铼第二代镍基单晶高温合金进行了热处理工艺的设计与优化,对合金的微观组织进行了观察并对不同热处理后合金的持久性能进行了测试。研究结果表明,通过金相法测出合金发生初熔的温度范围为1 275~1 280℃;合金经多级固溶处理后,偏析得到明显改善,共晶组织基本消除,且孔隙的数量较少;合金经1 100℃/4 h A.C.+870℃/20 h A.C.(A2)和1 120℃/4 h A.C.+870℃/20 h A.C.(A3)时效处理后,γ′相的尺寸在0.45~0.5μm,体积分数在60%~70%;经A2和A3时效处理后的合金在1 038℃/172 MPa下持久寿命分别为268.02 h和268.48 h,该低铼合金最终确定的热处理工艺为1 275℃/2 h+1 285℃/2 h+1 300℃/4 h+1 310℃/4 h+1 312℃/4 h A.C.+1 100℃/4 h A.C.+870℃/20 h A.C.。

In this paper, the heat treatment process of a low rhenium nickel base single crystal superalloy was designed and optimized. The microstructure of the alloy was observed and the stress rupture properties of the alloy after different heat treatments were tested. The initial melting temperature determined by metallographic test was between 1 275 ℃ and 1 280 ℃. After multi-stage solution treatment, the segregation was significantly improved, and the number of pores was small. After aging at 1 100 ℃/4 hA.C.+870 ℃/20 hA.C.(A2) and 1 120 ℃/4 hA.C.+870 ℃/20 hA.C.(A3), the size of γ′ phase was between 0.45 μm and 0.5 μm, and the volume fraction of γ′ phase was between 60% and 70%. The stress rupture life of the alloy aged by A2 and A3 at 1 038 ℃/172 MPa were 268.02 h and 268.48 h, respectively. The final heat treatment process was determined as 1 275 ℃/2 h+1 285 ℃/2 h+1 300 ℃/4 h+1 310 ℃/4 h+1 312 ℃/4 hA.C.+1 120 ℃/4 hA.C.+870 ℃/20 hA.C..