THE CASE FOR ULTRAHIGH-CARBON STEELS AS STRUCTURAL-MATERIALS

Ultrahigh-carbon steels (UHCSs)are low-alloyed plain carbon steels con taining 1-2.1 % carbon. These steels have remarkable structural proper ties when processed to achieve fine ferrite grains with fine spheroidi zed carbides. They can be made superplastic at intermediate temperatur es. Further, they can be made hard with compression toughness and stro ng with good tensile ductility at ambient temperatures. Contrary to co nventional wisdom, UHCSs are ideal replacements for currently used hig h-carbon (0.5-1 % carbon) steels because they have comparable ductilit y but higher strength and hardness. In this article, examples of struc tural components formed from fine-grained spheroidized UHCSs are illus trated, and other potential structural applications are reviewed. Thes e steels can be laminated with other metal-based materials to achieve superplasticity, high impact resistance, exceptionally high tensile du ctility, and improved fatigue behavior.