镍基IN718合金时效过程中α-Cr相演变行为

Evolution Behavior of α-Cr Phase During Long-Term Exposure of IN718 Alloy

通过力学性能试验,扫描电镜观测和化学重量分析,研究了直接时效与标准热处理工艺处理的IN718合金盘材经593℃～677℃高温长期时效至2 000 h后力学性能和微观组织行为.结果表明,直接时效的DA718合金在未经长期时效前已含有约0.006 w/%的α-Cr相,于650℃和677℃时效2 000 h后α-Cr相均达0.6 w/%左右,而在相同时效条件下,标准IN718合金α-Cr相比DA718要少.合金强度的变化规律与冲击韧性明显不同,2种合金微观组织演变行为也有明显区别,特别是α-Cr和δ相的变化行为.因此,合金微观组织行为对综合力学性能的影响需要进行综合考虑.

The mechanical properties and microstructure behavior of directly aging and standard heat treatment IN718 alloy after long-term aging at 593°C-677°C have been investigated. The experimental results show that the mass fraction of α-Cr phase in DA718 before exposure has been about 0.006wt%, after aging for 2 000 h at 650°C and 677°C, the α-Cr mass fraction is up to [similar to] 0.6wt%. While at the same aging condition, the α-Cr mass fraction in standard IN718 is ower than that in DA718. The strength change with aging is different from the impact ductility, and the microstructure evaluations for standard and DA718 alloys are also obviously different, especially α-Cr and δ precipitation behavior.