THE CASE FOR ULTRAHIGH-CARBON STEELS AS STRUCTURAL-MATERIALS

Ultrahigh-carbon steels (UHCSs)are low-alloyed plain carbon steels containing 1-2.1 % carbon. These steels have remarkable structural properties when processed to achieve fine ferrite grains with fine spheroidized carbides. They can be made superplastic at intermediate temperatures. Further, they can be made hard with compression toughness and strong with good tensile ductility at ambient temperatures. Contrary to conventional wisdom, UHCSs are ideal replacements for currently used high-carbon (0.5-1 % carbon) steels because they have comparable ductility but higher strength and hardness. In this article, examples of structural components formed from fine-grained spheroidized UHCSs are illustrated, and other potential structural applications are reviewed. These steels can be laminated with other metal-based materials to achieve superplasticity, high impact resistance, exceptionally high tensile ductility, and improved fatigue behavior.