Influence of processing route and section size on elevated temperature tensile properties of 9Cr-1Mo ferritic steel

Abstract

Tensile tests were performed on specimens obtained from 20 mm plate in normalised and tempered condition and quenched and tempered thick section tubeplate forging to assess the influence of processing route and section size on room and elevated temperatures (300-873 K) tensile properties of 9Cr-1Mo ferritic steel. Yield and ultimate tensile strength values of plate and tubeplate forging exhibited a gradual decrease up to intermediate temperatures followed by a rapid decrease at high temperatures. Ductility values displayed a gradual decrease to a minimum at intermediate temperatures followed by an increase at high temperatures. The fracture mode remained transgranular. At intermediate temperatures, 9Cr-1Mo steel in both the product forms exhibited similar serrated flow, an important manifestation of dynamic strain ageing. At all temperatures, thick section tubeplate forging exhibited lower strength and higher ductility values compared to normalised and tempered steel. The inferior strength values were attributed to coarse microstructure of the forging. Copyright © 2012 De Gruyter.