Thermomechanical Processing Effects on the Elevated Temperature Behavior of Niobium Bearing Fire-Resistant Steel

摘要

Microalloying has been shown to enhance the elevated temperature properties of fire-resistant (FR) steels, and variations in the thermomechanical processing schedules of a niobium containing structural steel were evaluated here. In particular, the thermomechanical processing strategy was intended to develop a ferrite substructure and determine its effects on the elevated temperature strength. By finish rolling within the warm working regime, it may be possible to generate a stable ferrite substructure capable of improving the elevated temperature strength of FR steels. Light optical microscopy was used to characterize the presence of ferrite substructure, and FR steel properties were characterized by elevated temperature tensile testing of the Nb containing steel using a servo-hydraulic tensile machine fitted with a clamshell furnace. The resulting FR properties were determined as a function of finish rolling temperature. The results suggest that worked ferrite enhances both room and elevated temperature properties, and may provide an important strengthening mechanism in FR steels.