Effect of ultrasonic surface rolling processing on stress field at crack tip of pipeline steel

The three-dimensional finite element model of cracked four point bending and ultrasonic surface rolling was established, and the four-point bending and ultrasonic surface rolling process was simulated by ABAQUS. The three-dimensional static crack's opening angle, displacement, crack tip stress field and J integral of four point bending specimen were analyzed before and after the ultrasonic rolling process. The mechanism of crack growth inhibition by ultrasonic surface rolling process was also discussed.The results show that the surface crack of the four point bending specimen was closed after ultrasonic rolling treatment, and the opening angle and displacement of the internal crack were obviously smaller than those without the ultrasonic rolling treatment. The tensile stress of crack tip decreased after USRP treatment, and the stress after 0.06 mm from the crack tip changed from tensile stress to compressive stress. The value of J-integral significantly reduced at the location of USRP, and the tendency of crack propagation is reduced.