Analysis of fracture appearance in CTOA testing of API X۶۵ steel

In the present paper, different stages of fracture process during CTOA testing of a modified double cantilever beam (MDCB) made from API X۶۵ steel was studied. During this experiment, the large observed CTOA values in the early stages of fracture were attributed to crack blunting, crack initiation, crack growth in flat fracture mode, and crack tunneling in the middle of test. The observed stable CTOA data after transit region of crack growth was associated to transformation of flat to slant fracture and to subsequent stable slant fracture. This was verified by SEM fractography of the fracture surface of the CTOA test sample.

Keywords:

API X۶۵ steel , CTOA , fracture surface , MDCB , ductile fracture