表面完整性对FGH95合金高温疲劳性能的影响

Effect of surface integrity evolution on high-temperature fatigue property of FGH95 alloy

金属构件的加工表面完整性状态对其整体疲劳性能具有显著影响。本工作研究了磨削、磨削+铸钢丸喷丸、磨削+陶瓷丸喷丸和磨削+复合喷丸4种表面加工集成方法对FGH95合金高周疲劳性能的影响规律。采用表面粗糙度仪、X射线残余应力测试仪和显微硬度计分别对不同复合加工方法试样的表面粗糙度、表面残余应力分布和硬度梯度等表面完整性参数进行了表征;采用旋转弯曲疲劳试验机测试了缺口(应力集中系数Kt=1.7)试样的旋转弯曲疲劳,研究不同表面完整性状态对缺口试样高温疲劳寿命的影响规律。结果表明:相对磨削,磨削+铸钢丸喷丸、磨削+陶瓷丸喷丸和磨削+复合喷丸三种方法均可显著提高试样的高温疲劳寿命;其中,磨削+复合喷丸方法获得了最优的表面残余应力场、硬度梯度、表面粗糙度和高温疲劳寿命增益效果。

Surface integrity state after machining has an important effect on the service life of metal parts and components.The effects of four kinds of surface integration processing methods on the high-temperature fatigue properties of FGH95 alloy were investigated.These four surface processing methods were AR(grinding),GCSSP(grinding and cast steel shot peening),GCSP(grinding and ceramic shot peening)and GDSP(grinding and double shot peening).The surface roughness,residual stress distribution and micro-hardness were characterized by roughness tester,X-ray diffraction(XRD)stress tester and micro-hardness tester.The rotating-bending fatigue life with notched specimens(stress concentration factor,Kt=1.7)was investigated.The results indicate that the fatigue life of specimens increased largely by GCSSP,GCSP and GDSP compared with AR specimens respectively.Furthermore,GDSP process can obtain the best surface residual stress field distribution,gradient distribution of micro-hardness,surface roughness and improvement of the high-temperature fatigue property.