固溶处理对新型镍钴基高温合金显微组织及力学性能的影响

Effect of solution treatment on microstructure and mechanical properties of a novel nickel-cobalt-based superalloy

采用OM、SEM和拉伸试验等研究了固溶温度和固溶时间对新型镍钴基高温合金组织及力学性能的影响。结果表明,晶粒尺寸变化与一次γ′相含量变化一致,固溶温度低于1110℃时,随着固溶温度升高或固溶时间延长,残留的一次γ′相钉扎晶界,晶粒尺寸增加较缓。固溶温度为1110℃时,延长固溶时间至4 h时,一次γ′相基本回溶,晶粒尺寸迅速增加,进一步延长固溶时间至6 h时,晶粒尺寸增加减缓,即合金中一次γ′相的全溶温度为1110℃。合金在1100℃固溶4 h和双级时效处理(670℃×24 h,空冷+780℃×16 h,空冷)后的抗拉强度和屈服强度达到最大值,分别为1584 MPa和1104 MPa。因此,合金的固溶温度宜选取为1100℃,固溶时间宜选取为4 h。

Effects of solution treatment temperature and time on microstructure and mechanical properties of a novel nickel-cobalt-based superalloy were studied by means of OM,SEM and tensile test.The results show that the evolution of the grain size is consistent with the change of the primaryγ'phase volume fraction.When the solution treatment temperature is below 1110℃,the grain size increases slowly with the increase of solution treatment temperature or time due to the grain boundaries pinning effect caused by the residual primaryγ'phase.When the solution treatment temperature is 1110℃,the primaryγ'phase is basically redissolved as the solution treatment time increases to 4 h,which results in a rapid increase of grain size.With further extending the solution treatment time to 6 h,the increase of grain size slows down,the temperature for full dissolution of theγ'phase in the tested alloy is 1110℃.In addition,after solution treatment at 1100℃for 4 h and two-stage aging treatment(670℃×24 h,air cooling and 780℃×16 h,air cooling),the tensile strength and yield strength of the alloy reach the maximum value,1584 MPa and 1104 MPa,respectively.Thus,the optimal solution treatment of the tested alloy are confirmed as at 1100℃for 4 h,respectively.