Study on Crack Sensitivity of High‐Mn Cryogenic Steel Slab in Bending and Straightening Zones of Continuous Casting

In recent years, the continuous casting production of high‐Mn cryogenic steel has attracted considerable attention. However, this process still faces problems such as surface cracks and even breakout, which are related to crack sensitivity of this steel. To investigate crack sensitivity of high‐Mn cryogenic steel slab in bending and straightening zones, Gleeble hot tensile tests and in situ material characterization‐bending were conducted. The results show that the strain is close to 0.2 within 800–950 °C. When the temperature exceeds 950 °C, the stress drops below 60 MPa. The tensile strength is decreased gradually with increasing temperature. It is over 150 MPa at 800 °C and less than 20 MPa at 1250 °C. Only at 1050 °C, the reduction of area is less than 40%, and the fracture surface exhibits intergranular cracks with almost no dimples. Finer and more uniformly distributed grains correspond to superior hot ductility of Mn25 steel. Moreover, maintaining the straightening temperature above 950 °C is recommended to avoid quality defects generated during straightening. No bending defects appear on the sample surfaces within 850–1050 °C. The high‐Mn cryogenic steel exhibits favorable hot ductility and relatively low crack sensitivity in the continuous casting straightening zone.