Influence of Rolling Process on the Equiaxed Grain Zone of Bars Produced by 410 mm × 530 mm Continuous Casting Billet

The large end face continuous casting billet is prone to a series of internal quality problems such as centre sparsity and shrinkage holes， irregular distribution of centre coarse equiaxial crystal zone when rolling large-size bars. Designed four different BD mills （BD is abbreviated for English blank， 1250 double roll reversible rolling mill used in this test） the open billet process on 42CrMo steel 410 mm × 530 mm specifications of continuous casting billet rolled to 255 mm × 255 mm size process to study， first using finite element simulation software for simulation of the rolling process， and then after the verification of industrial tests on the final 180 mm bar finished products for macrostructure test. The results show that the use of large reduction amount rectangle → square → rectangle alternating deformation mechanism process for rolling， can effectively improve the heart of the material produced loose， shrinkage defects， and at the same time， continuous casting billet heart of coarse isometric crystals inherited to the size of the material produced is close to 1：1 to optimize constructure symmetry of the material produced to facilitate the subsequent use of the customer. Moreover， the comparative analysis of the simulation results and industrial test results shows that the application of finite element simulation technology in rolling deformation has high accuracy， and the rolling process through finite element simulation can effectively shorten the test period and reduce the cost of process optimization.