Effect of Hydrogen Concentration and Residual Stress on the Delayed Cracking Performance of the 22MnB5 Hot Roll Bending Pipe

The microstructureMicrostructure and delayed crackingDelayed cracking performance of the 22MnB5 hot roll bendingHot roll bending pipe was analyzed in this study. The main microstructureMicrostructure of the surface and central zones of the pipe were martensite and ferrite before and after annealing. The delayed crackingDelayed cracking test indicated that the annealed pipe possessed better delayed crackingDelayed cracking performance than the original one. The residual stressResidual stress of the original and the annealed pipes was tensile stress. In particular, the tensile stress at the outer bending of the pipe was the largest. The hydrogen contentHydrogen content at the inner and outer bending zones increased slightly after annealing. The crackCrack after soaking in acid was only observed at the outer bending zone of the pipe. According to the test results of residual stressResidual stress and hydrogen contentHydrogen content, it was deemed that the larger residual stressResidual stress could induce the cracksCrack. Meanwhile, no obvious effect of the hydrogen contentHydrogen content on the delayed crackingDelayed cracking performance could be detected.