单晶高温合金持久性能各向异性分析

Analysis on the stress rupture properties’ anisotropy of single crystal superalloy

为阐述单晶高温合金持久性能各向异性规律,收集了Mar-M247、RR2000、DD6、PWA1484、CMSX-2、CMSX-4、Alloy454与SC7-14合金的持久寿命数据,调研文献探索其影响因素,总结了近〈001〉取向小角偏离对持久寿命的影响,研究晶体取向与持久寿命间的关系,定量分析了温度对持久性能各向异性的影响。结果显示:{111}〈112〉滑移系的"位错滑移"与"晶格转动"是中低温下(760~850℃)单晶合金持久性能各向异性的重要原因;偏角相同的条件下,靠近"[001]~[011]"边界的近〈001〉取向持久性能相对优异;不同牌号单晶合金持久性能各向异性规律不同,不存在恒定的"持久性能最优取向";随着温度升高,晶体取向对持久性能影响减弱,针对DD6与CMSX-4合金,高温下(大于950℃)可用〈001〉热强综合参数曲线评估〈011〉与〈111〉取向的持久强度。

In order to elaborate the anisotropy of the stress rupture properties of single crystal superalloys, experimental data about rupture time of Mar-M247, RR2000, DD6, PWA1484, CMSX-2, CMSX-4, Alloy454 and SC7-14 were collected. In addition, the influencing factors were confirmed by literature review. The effect of small deviations from 〈001〉 on the rupture lives was summarized based on the data, then further analysis was carried out to establish the relationship between the crystallographic orientation and the rupture time. Finally, the influence of temperature on the anisotropy of stress rupture properties was analyzed quantitatively. Results showed that: "dislocation glide" and "lattice rotation" of {111}〈112〉 slip systems were important reasons for the anisotropy at intermediate temperatures(760-850 ℃);the orientations near 〈001〉 could show a better rupture performance, if they were closer to the "[001]-[011]" boundary. The anisotropy of stress rupture properties was different among different single crystal superalloys, and there was no such orientation presenting always the best performance. As the temperature increased, the creep anisotropy was significantly reduced. For DD6 and CMSX-4, the "time-temperature" parametric curve of 〈001〉 could be used to evaluate the rupture strength of samples oriented 〈011〉 and 〈111〉 at high temperatures(above 950 ℃).