Determination and modelling of the influence of cooling in the coil on the mechanical properties of hot strip steels with bainite

The phenomenon of bainite formation in the hot strip mill for unalloyed steels and the influence of the complex cooling process have hardly been dealt with in literature. Only two useful model equations were found, namely according to Suehiro et al. [4] for the determination of the strength parameters R-p0.2 and R-m of annealed bainite, and according to Umemoto et al. [2] for the calculation of the tensile strength R-m of bainite formed during the isothermal holding temperature. These equations could be optimized by structural complements and modification of the coefficients by adjusting them to the own measured values. For building up the necessary data base, experimental methods were developed, involving the use of a computerized deformation dilatometer. The results thus obtained can be applied to the industrial practice.