Residual stress analysis of multi-pass cold spinning process

Uncontrolled residual stresses have significant effects on the service time and defects of the spun parts. Nowadays, X-Ray Diffraction (XRD) method has been widely used in the residual stress measurement of industry products with different forming processes. The calculated residual stress is usually obtained from the data fitting slope of strain and angle with Ordinary Least Squares (OLS) method. But this fitting method is not always suitable for the big fluctuant data. In this paper, the Weighted Least Square (WLS) method is used for the data fitting and compared with the OLS method. The nickel-based superalloy GH3030 and iron-based superalloy GH1140 are applied in the multi-pass cold spinning experiments. The residual stress distributions of normal, potential crack and wrinkle workpieces are discussed with the grain structure. The results show that WLS method has better goodness of fit compared with OLS method. The residual stress distributions have special relationship with potential crack, wrinkle workpiece and grain structure.