激光温喷丸IN718镍基合金残余应力高温释放行为

Thermal Relaxation Behavior of Residual Stress in Warm Laser Peened Inconel718 Superalloy

摘要:

为了研究激光温喷丸对IN718镍基合金高温释放行为的影响，以20 ℃常温激光喷丸(LP)和260 ℃激光温喷丸(WLP)处理的IN718镍基合金为研究对象，从微观组织、残余应力等角度，通过保温试验探索了温度、时间与残余应力释放的关系，并从高温软化和蠕变理论角度对残余应力的高温释放规律进行分析。结果表明，WLP较LP处理的IN718镍基合金具有更好表面高温稳定性和更高位错密度，且晶粒细化更为明显；随着保温温度的升高，LP和WLP处理件残余应力释放幅度均明显增大，但前者释放速度更快，且位错密度有明显减小的趋势；700℃保温500min后，LP和WLP处理件表面残余应力分别释放了68%和36.7%，最大残余应力释放率出现在保温初始阶段，且释放规律符合Zener-Wert-Avrami函数。

Abstract:

In order to study the influence of warm laser peening on the thermal relaxation behavior of Inconel718 superalloy, the LP(20℃) IN718 and WLP(260℃) IN718 are served as the research objects. From the view points of microstructure and residual stress, the relationship between temperature, time and residual stress are explored by experiments. The thermal relaxation behavior of residual stress are analyzed from the perspective of material softening and creep-controlled behavior at elevated temperature. The results show that the WLP(260℃) IN718 superalloy has a better performance in residual stress stability, grain size and dislocation density compared with LP(20℃) IN718; the relaxation amplitude increases with the increase of applied temperature, and the thermal stability and dislocation density of residual stress in LP(20℃)IN718 is better than that in WLP(260℃) IN718; the maximum rate of stress relaxation take place at the initial stage of peening process in all conditions, the LP(20℃) and WLP(260℃) surface residual stress have released 68% and 36.7% respectively after exposed 500min at 700℃. Thermal relaxation behavior can be described by Zener–Wert–Avrami function.