The High Strength Cold Forging Applications of a New Multi-Phase Steel 910145
High strength fasteners and cold forgings are typically produced from carbon or low alloy steel. While the final components usually exhibit adequate mechanical properties such as strength, toughness and fatigue resistance, the cost of producing components using these conventional steels is unattractively high. A large portion of these costs originate in the nature of the steel chosen for fabrication. The cumulative cost of total material-related processing, e.g. spheroidize annealing required before cold forging plus that of the QT and stress relieving heat treatments following cold forging, renders the total process rather cost ineffective. An ideal steel for cost-effective cold forging must exhibit the following characteristics: (i) Good bulk formability in the hot rolled bar or rod form, (ii) Should be capable of generating high strengths during the cold forging process, and (iii) Should retain good toughness in the final component. A new steel for high strength cold forging applications, which has the characteristics of the ideal steel, has been developed by The Basic Metals Processing Research Institute of University of Pittsburgh. This new microalloyed steel, called BHS-1, exhibits a multiphase microstructure which, can be developed during controlled hot processing of bar or rod. Laboratory and industrial trials have shown that this new steel is capable of attaining very high strengths, ductilities, notch toughness and fatigue resistances in a variety of applications and is a viable cost-effective substitute for conventional QT steels.