During the bending and straightening process of low carbon microalloyed steel, high-temperature microstructure (HTM) governs the slab corner transverse cracking susceptibility. In this paper, the stiffness was used to characterize the resistance ability of HTM to elastic deflection, and a model describing the relationship between the stiffness and characteristics of HTM was established. The criterion was created based on the HTM features for the slab corner transverse cracking susceptibility. The results are mainly manifested in two aspects: 1) the stiffness was used to characterize the resistance of HTM against the elastic deformation, and it can also indirectly reflect the relationship between prior austenite grain and film-like ferrite, second-phase precipitate. 2) The critical equivalent diameter of the prior austenite generating the slab surface transverse cracks was found to be 0.68 mm. If the equivalent diameter of the prior austenite (DγP) became >0.85 mm, the index of the traverse crack on the surface of slab increased sharply, indicating strong susceptibility of transverse corner cracks.
