The structure and properties of warm-rolled steels

Abstract

Abstract Microstructure, tensile properties and fracture behaviour were examined in both warm-rolled rods (1150°F, 621°C) and in conventionally hot-rolled rods (1950°F, 1065°C) of four carbon grades (1015, 1038, 1060 and 1090). Both spheroidization of carbides and the development of substructure in the ferrite were produced during warm rolling. The fracture facets were more irregular, indicating an increased amount of plastic tearing, than in the conventionally hot-rolled bars. Compared with hot rolling, the warm rolling caused an increase in yield stress (all grades), in reduction of area (all grades except 1015) and in ratio of yield stress to ultimate tensile stress. The total elongation, with the exception of 1090 steel, was decreased. In the1090-grade rods, the shelf energy for the tear fracture was significantly increased, although the transition temperature was affected very little by warm rolling. In contrast, warm rolling has produced a marked decrease in shelf energy and a 30°C increase in trans...