modelING iMPACT TOUGHNESS OF INDUSTRIAL HOT ROLLED HSLA STEELS

A quantitative model has been developed to predict the temperature dependence of impact toughness (KCV) for hot rolled plane carbon and HSLA steels with a wide range of chemical composition (wt%): С(0.04-0.21), Mn(0.16-1.96), Si(0.01-0.93), Cr(0.01-0.97), Ni(0.01-0.51), Cu(0.02-0.45), Mo(0.001-0.50), Nb(0.001-0.056), V(0.002-0.09), Ti(0.001-0.08), N(0.003-0.009), S(0.001-0.032), P(0.005-0.025). The transition temperature at 50 % of fibrous fracture ( FATT 50 ) is determined in terms of chemical composition and calculated final microstructure parameters. Impact energies at lower ( KCV LS ) and upper ( KCV US ) shelves are derived from predicted values of tensile stress and relative elongation. All physical parameters of the model are related to the industrial hot rolling conditions by means of the integral computer model STAN 2000 previously formulated for the rolling mill 2000 of PJSC Severstal. Empirical coefficients are fitted to the data base on impact toughness for 230 plates of 32 steel grades in the temperature range of -60°С to +20 °С. The modelling results comply well with experiments.