Surface-crack formation in the manufacture of microalloyed steel pipe

Deform-3D software is used to model surface-crack formation in the rolling of thick sheet on a 5000 mill. The calculations show that the temperature field and stress state are relatively uniform over the width of the sheet, except at the edges. The minimum temperature of the surface layers of metal hardly depends on the sheet thickness and the relative reduction per pass. The Cockroft–Latham criterion is used to analyze the probability of steel failure in rolling. Analysis shows that metal failure may occur at points where ferrite appears, especially at the instant that the metal leaves the deformation region. Considerable tensile stress acts at those points.