基于二维面探的高温合金GH4169残余应力分析

Residual Stress Analysis of High Temperature Alloy GH4169 by Two-dimensional Detector Method

目的通过二维面探X射线衍射法测试高温合金GH4169的残余应力。方法由于GH4169是Ni基高温合金,Ni合金在Cr靶下有较强衍射峰,因此采用Cr靶来测试GH4169合金的残余应力。二维面探仪有500个探测头,均匀分布在一个面上,根据每一个探测器测得的衍射角变化,就能得到500个方向上的应变值,再根据应力与应变之间的关系,就可以计算出材料的残余应力。结果 GH4169合金的德拜环只有一个衍射峰,而且衍射峰的强度随着角度α的变化而变化。这说明该材料的应力取向不均匀,存在较为明显的织构。该材料表面主应力方向上的残余应力测试值为-968 MPa,误差为62 MPa;切向上的残余应力测试值为24 MPa,误差为43 MPa。由于测试的GH4169合金是经过喷丸处理的,主应力方向上受残余压应力,而其测试结果确为负值,说明此次测试结果可信。结论通过二维面探X射线衍射方法测试材料残余应力从原理和实际操作上都是可行的,并成功测试出GH4169合金的残余应力。经喷丸处理后的GH4169材料受残余压应力的作用,且应力分布不均匀,存在较为明显的织构。

Objective To measure the residual stress of GH4169,a kind of high temperature alloy,using two-dimensional detector method. Methods Because GH4169 is a high temperature nickel base alloy which has a strong diffraction peak under the Cr target,this paper used Cr target to obtain the residual stress of GH4169 alloy. Using 500 detection heads uniformly distributed on a surface to measure diffraction angle changes,the portable X-ray machine could get the values of strain in 500 directions. According to the relationship between stress and strain,the residual stress of the material could be calculated. Results The Debye ring of GH4169 alloy hasd only one diffraction peak and its intensity changed with the changes of angle alpha. This result showed that the stress orientation of the material was not uniform,with obvious texture. The residual stress in the principal stress direction of the material surface was-968 MPa with an error of 62 MPa,and the tangential residual stress was 24 MPa with an error of 43 MPa.Shot peened GH4169 alloy was affected by the residual compressive stress,which was consistent with the experiment results.Conclusion It was feasible to measure the residual stress of the material from the principle and the practical operation by the twodimensional detector method which effectively measured the residual stress of GH4169 alloy. Moreover,shot peened GH4169 alloy was affected by the residual compressive stress,the distribution of which was not uniform and had obvious texture.