Mean-Flow-Stress Analysis of Laboratory Hot-Rolled S1100Ql Steel with Minor Nb Addition

Abstract

Laboratory hot-rolling of ultra-high-strength martensitic steel S1100QL was carried out by measuring the material resistance during hot-rolling using rolling force measurements. A simplified approach was used to calculate the mean flow stress as an indirect method to analyse the material's response during hot rolling. It was shown that the method gives satisfactory results, regarding the rough detection of different temperature-deformation regions like crossing the region of considerable solute drag and precipitation hardening, known as the non-recrystallization region. The transition from the recrystallization region, where softening mainly by static or meta dynamic recrystallization is replaced with a non-recrystallization region having austenite pancaking, is clearly distinguishable for given rolling parameters and final strip thickness. The grain size distribution of the S1100QL was also evaluated from the as-cast state to the heat-treated condition.