Residual stress and micro-structure of GCr15 steel after multistep shot peening

Experiments were conducted to investigate the effects of different shot peening (SP) techniques on the residual stress and micro-structure of GCr15 steel by X-ray diffraction (XRD) profile analysis. The results showed that SP induced the martensitic phase transformation, compressive residual stress (CRS) and micro-structure modification within the deformed layer. Under the optimum SP intensity of 0·52+0·25+0·16 mmA, the maximum compressive residual stress (MCRS) for martensite attains 745 MPa at the depth of 35 μm while the MCRS for austenite attains 869 MPa at the depth of 50 μm; and the domain size of GCr15 steel attains the minimum value of 9 nm at the top surface; The micro-strain and dislocation density attain the maximum values of 0·0042 and 2·29×10¹⁵ m⁻² at the top surface respectively.