Influence of quenching conditions on texture and mechanical properties of ultra-high-strength steels

Direct quenching of thermomechanically processed low-carbon steels is a preferred production route to increase strength and toughness of ultra-high-strength steels and thus enhance the payload-to-weight ratio, e.g., of mobile cranes. However, during hot rolling, certain crystallographic textures emerge, which can generate unfavorable mechanical properties or mechanical anisotropy. In order to investigate the role of the processing route and the effect of micro-alloying elements on the texture formation and its relationship to differences between different testing directions, four different ultra-high-strength steels were subjected to various quenching procedures. It was found that despite equiaxed prior austenite grains after re-austenitization, differences in the longitudinal and transverse directions remain. The extinction of a rolling texture after re-austenitization is dependent on the austenitization condition and the addition of micro-alloying elements. In particular, Nb promotes the formation of rolling texture components and prevents the extinction thereof even through intense austenitization treatments. However, remaining preferred orientations exhibit only little influence on the anisotropy of the mechanical properties.