Research into Causes of Surface Cracks Formation in Rolling Plates and Manufacturing Pipes of Microalloyed Steel Grades. The Peculiarities of Rolling in the Dual Phase Region
The causes of the surface defect «bondage type petal» which manifests itself in the final stage of production of large diameter pipes were investigated in this study. It is assumed that superficial microcracks occur in rolling of plate due to the occurrence of weak link by rolling in a dual-phase region and the localization of plastic deformation, to tensile stresses in the surface layer and achieve fracture criterion limits. Limit stresses (tensile strength) while rolling in the two-phase region, with a complex structure and temperature dependence of the sensitivity of the value determined by the ferrite and bainite transformation in steel were defined by physical simulation on Gleeble.