热处理对FGH96合金异常晶粒长大的影响

Effect of Heat Treatment on Abnormal Grain Growth of FGH96Superalloy

基于FGH96合金双锥体试样压缩变形实验及短时加热实验,研究热处理工艺对异常晶粒长大的影响规律,分析异常晶粒长大初始过程的晶粒组织及γ′相。结果表明:具有相同局部应变的双锥体试样经过固溶热处理时,会出现异常晶粒组织,而亚固溶热处理不会出现异常晶粒组织。当压头速率为0.1mm/s及0.008mm/s时,经过固溶热处理的双锥体试样,均会在保温时间小于30s时,局部出现具有较大晶粒的不均匀组织,最终成为异常晶粒。采用过固溶热处理,晶界上的二次γ′相会在到达固溶温度后的60s内几乎完全溶解,其对晶界的钉扎作用消失。采用亚固溶热处理,晶界上的γ′相不会发生溶解,会阻碍晶界的迁移,不会发生晶粒异常长大。

Based on the compression experiments and short time heating experiments of FGH96 super- alloy double cone （DC） specimens, the effect of heat treatment process parameters on abnormal grain growth （AGG） was studied. The grain microstructure and γ＇ precipitates were analyzed at the initial stage of AGG. The results show that AGG can occur after supersolvus heat treatment, which is con- trast to subsolvus heat treatment for FGH96 DC specimens with the same local strain distribution. After the compression of DC specimens with the crosshead speed of 0. lmm/s and 0. 008mm/s, larger grains occur within less than 30s supersolvus heat treatment time, which become AGG at last. The secondary 3tr precipitates in grain boundary almost dissolve within 60s supersolvus heat treatment time, and the inhibition for the grain boundary migration disappears. In contrast to supersolvus heat treatment, the ~/＇ precipitates in grain boundary don^t dissolve completely during subsolvus heat treat- ment, which inhibit the grain boundary migration and AGG.