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为研究激光喷丸镍基合金残余应力的高温松弛行为,首先对IN718合金进行单次激光喷丸强化,随后,对喷丸后试样进行高温保持,对比分析了不同保温温度和不同保温时间下残余应力值、半峰宽值(FWHM)变化及晶粒演变特征。结果表明,激光喷丸后,喷丸区域呈残余压应力状态,FWHM值升高,近表层材料晶粒明显细化;高温保持过程中试样的残余应力松弛量与保温温度和保温时间呈正相关。应力松弛速率在保温初期较大,随后逐渐减小。保温温度为800℃,保温时间为300 min时,残余应力松弛量最大,松弛幅度达82.14%。保温温度一定时,材料表面FWHM值下降幅度随保温时间的增大而增大,600℃保温温度下,FWHM值变化不明显。600℃保温300 min后材料的晶粒尺寸仍较小,晶粒细化效应仍然显著,而800℃保温下晶粒长大迅速,保温300 min后材料的晶粒细化效应基本消失。
In order to study the high-temperature relaxation behavior of laser shot-peening nickel-base alloy residual stress, a single laser shot peening of IN718 alloy was carried out firstly. Then the sample after shot peening was kept at high temperature. The effects of different holding temperature and holding time Residual stress value, FWHM variation and grain evolution characteristics. The results show that after shot peening, the shot peening area is under residual compressive stress and the FWHM value is increased, while the grains in the near surface layer are obviously refined. The residual stress relaxation during the high temperature holding is positively correlated with the holding temperature and holding time . Stress relaxation rate in the initial insulation larger, then gradually decreased. When the holding temperature is 800 ℃ and the holding time is 300 min, the residual stress relaxes to the maximum with a relaxation rate of 82.14%. When the holding temperature is constant, the decrease of FWHM value of the material surface increases with the increase of holding time, and the FWHM value does not change obviously under the holding temperature of 600 ℃. After 300 min of 600 ℃, the grain size of the material is still small, and the effect of grain refinement is still remarkable. However, the grain growth at 800 ℃ is rapid. After 300 min of annealing, the grain refinement effect of the material disappears.