Effects of Steel Processing on Property Variations in Eglin Steel (ES-1)

摘要

Eglin steel (ES-1) was developed by the U.S. Air Force under a Dual Use Science and Technology contract (F0863 0-00-2-0001) as a cost-effective, ultrahigh-strength steel for military and commercial applications demanding rigorous impact toughness. The alloy contains a large tungsten addition (1 wt%) to produce a fine distribution of tungsten carbides between martensitic laths. The carbides serve as sites for dislocation pinning to produce significant work hardening and allow for high impact toughness properties. To optimize toughness, melting and refining practices are controlled to improve steel cleanliness (inclusion content) and high temperature processing treatments limit the degree of micro-segregation for better control of the carbide stability and distribution. The focus this study was to evaluate the effect of steel processing on the physical and mechanical property variations in ES-1. To better understand variations in impact properties, the inclusion and carbide content were quantified for samples produced with controlled combinations of melting, refining and heat treatment. The statistical evaluation of the carbide and inclusion content was conducted using an analytical SEM particle scanner to classify the number, size, shape, distribution and composition.