Residual stress measurement of coarse-grain aluminum alloy using X-ray diffraction method

When measuring residual stress of coarse-grain aluminum alloy using X-ray diffraction method,the diffraction profile shows two peaks and position of measured 2θ will be changed,which lead to an inaccurate measurement result.Hence,in this paper,some methods were employed to improve the measurement accuracy.During the measuring process,different parameters (diameter of irradiated area,ψ-oscillation range and exposure time) were selected and profile peak shift method was utilized.Moreover,when the 2θ of profiles was determined,different calculation methods were used to calculate the residual stress.The results show that diameter of irradiated area and ψ-oscillation range have significant influence on the measuring result.For stress value calculated directly from the test equipment,cross correlation method is more accurate than the absolute peak.Furthermore,another two calculation methods of slope with 2θ-sin2ψ and ε-sin2ψ were used to calculate the stress based on parameters (2θ,ε) obtained from cross correlation method.It is concluded that 2θ-sin2 ψ method can further improve the measurement accuracy.