Cause Analysis of Delamination Cracking of TiC Strengthened Antifriction Steel during Cold Bending

Abstract In order to analyze the causes of delamination cracking of 400 HB class TiC strengthened antifriction steel during cold bending, the morphology, chemical composition and distribution of non-metallic inclusions in the central part of the thickness (1/2 thickness) and other parts of the cracked sample were analyzed by optical microscope, scanning electron microscope and energy dispersive spectrometer (SEM-EDS), electron probe (EPMA). The results indicate that there are large-sized inclusions composed mainly of oxides of elements such as Ti, Si, Mn, which extend along the rolling direction and have a length exceeding 200 μm at the 1/2 thickness of the sample. In other parts of the sample, the inclusions are mainly particles of Ti(C, N), Al 2 O 3 and other types, with relatively small sizes and uniform distribution. The large inclusions with a length exceeding 200 μm, located at 1/2 thickness, are the direct cause of cold bending delamination cracking.