GH4169疲劳试样加工残余应力的表征及其对低周疲劳寿命的影响

Characterization of residual stresses during machining of GH4169 fatigue specimens and the effect on low cycle fatigue life

为了探究GH4169合金低周疲劳试样加工过程中表面残余应力的变化及残余应力对低周疲劳性能的影响,采用X射线衍射法对“车-磨-抛”不同加工工艺的试样表面残余应力进行表征及对成品试样进行残余应力层深度测试,通过中子衍射法对试样内部进行残余应力测试。采用电液伺服万能试验机进行了低周疲劳试验。结果表明:GH4169合金低周疲劳试样加工表面残余应力随着切削量的增加由表面残余压应力变为残余拉应力。根据残余应力层深度测试,机加工对试样表面造成残余应力层深度小于0.01 mm,内部残余拉应力减小;根据疲劳试验结果,GH4169合金疲劳寿命与表面轴向残余压应力呈正相关关系。

In order to investigate the changes in surface residual stresses and the effect of residual stresses on the low cycle fatigue properties of GH4169 alloy specimens during the machining process,X-ray diffraction was used to characterize the surface residual stresses of specimens with different machining processes of "turning-grinding-polishing" and to test the depth of the residual stress layer of the finished specimens.The residual stresses were measured inside the specimens by neutron diffraction.Low-cycle fatigue tests were carried out using an electro-hydraulic servo universal testing machine.The results show that the residual stresses on the machined surface of GH4169 alloy change from surface residual compressive stresses to residual tensile stresses as the cutting volume increases.According to the residual stress layer depth test,machining on the surface of the specimen caused residual stress layer depth less than 0.01 mm,the internal axial residual tensile stress decreases.According to the fatigue test results,GH4169 alloy fatigue life and surface axial residual compressive stress is positively correlated.