Fracture analysis on a cylindrical shell section of the low-pressure absorption tower

Cracking of a cylindrical shell section from an absorption tower occurred during the hydraulic pressure testing. In order to find out the cause of failure, the cracked cylindrical shell section was inspected and destructively analyzed. Optical microscopy was performed to evaluate the basic microstructure of the material used to fabricate the cylinder and the effect of welding on the microstructure. The fracture surface was examined in a scanning electron microscope, and the effects of the heat treatment temperature on the structure and properties of 410S/16MnR explosively clad plate were investigated. Detailed metallographic studies indicated that bainite existed in the base layer of the explosively welded material. The weld-induced residual stress in the crack origin was investigated by a three-dimensional (3D) finite element model. The numerical result was consistent with the fracture analysis supporting the conclusion that cracking was caused by the poor mechanical properties of the explosively clad plate and that the poor properties were induced by improper heat treatment after explosive welding. The welding residual stresses also contributed to the failure process.