Development of Eglin Steel-A New, Ultrahigh-Strength Steel for Armament and Aerospace Applications

摘要

Eglin Steel has been developed by the U. S. Air Force and Ellwood National Forge Company as a cost-effective, ultrahigh-strength steel for application in armament, aerospace, and commercial applications. The unique, patent-pending composition and processing of Eglin Steel result in strength and toughness properties comparable with much more highly alloyed steels such as AF1410, HP 9-4-20, and HP 9-4-30. The lightly tempered martensitic/bainitic microstructure of Eglin Steel produces good toughness and continuous yielding during tensile loading. A high degree of strain hardening is achieved, as indicated by a yield strength/tensile strength ratio (YS/TS) of 0.8. The more highly alloyed steels typically exhibit YS/TS ratios of 0.9. High strain rate tensile testing has demonstrated good performance at impact-like strain rates. Tensile properties, notch toughness, fatigue performance, and fracture toughness results from full size production components will be presented. The fine scale microstructure and precipitates developed with various heat treatments have been characterized with transmission electron microscopy (TEM) extraction replica studies and selected area electron diffraction (SAD).