Cause of hot shear cracking of GCr15 bar

In the process of hot shear blanking of a hot rolled GCr15 bar, there was cracking on the shear surface. The cracking reason was analyzed by macroscopic observation, ultrasonic testing, chemical composition analysis, scanning electron microscope analysis and metallographic examination. The results show that the central stress crack at the end of the hot rolled bar was the main cause of shear cracking, and the central stress crack at the end of the bar was related to the failure of timely annealing or slow cooling after rolling.