Effect of mechanical shot peening on fatigue property of X80 pipe steel

In order to identify the effect of mechanical shot peening on fatigue property of X80 pipe steel, the pneumatic type shot peening machine is used to treat the X80 pipe steel sample, and residual stress distribution on both sides of the holes of single-linkage central hole sample before and after mechanical shot peening is tested. Then, the effect of mechanical shot peening time on the fatigue life of X80 pipe steel is discussed, and the fatigue fracture morphology of single-leakage central hole sample before and after mechanical shot peening is analyzed. The test results show that high magnitude compressive residual stresses are distributed on the surface of X80 pipe steel, which reduce the growth rate of fatigue crack significantly, and the fatigue life has improved obviously. Through scanning the fatigue fracture, fatigue crack source of the sample without shot peening is found at the corners of the upper surface of the hole wall, and the crack source of the sample within mechanical shot peening is gradually shifted into the strengthening layer. In the stable extension area of fatigue crack, fatigue banding spacing decreases with the increase of mechanical shot peening time. It shows that mechanical shot peening effectively reduces the fatigue crack growth rate of pipe steel and the fatigue property of X80 pipe steel is improved.