Investigation on the Delayed Cracking Performance of the 22MnB5 Hot Roll Bending Pipe

22MnB5 steel possesses a promising application in the structural components in automobile industry mainly attributing to its low cost combined with the high mechanical propertiesMechanical properties. The delayed crackingDelayed cracking behavior of the 22MnB5 steel in the solution of 0.1 mol/L HCl with various times is comparatively investigated. By observing the crack initiationCrack initiation and propagation during the delayed crackingDelayed cracking test, it can be found that the initiation of the cracks exists an incubation period, and the cracks appear after being soaked in acid for 3 h. In particular, the crack initiationCrack initiation location is highly related to the position of the pipe, especially the inner bending zones reflect much higher susceptibility of the delayed cracks. The hydrogen can easily accumulate in the bending zones with large residual stress. The interaction between hydrogen and metal atoms can possibly weaken the cohesion of the grain boundaries, eventually trigger the initiation of the cracks.