HIGH MN, HIGH AL STEELS FOR THICK PLATE ARMOR APPLICATIONS

FeMnAlC alloys exhibit lower density (6.5-7.2 g/cm³) than traditional military steels (7.9 g/cm³) while maintaining similar energy absorption capabilities. Material substitutions in legacy systems must meet existing form/fit/function requirements, limiting opportunities for lightweighting of existing designs. This study examines production and material properties of thick plate with a nominal chemistry of 30% Mn, 9%Al and 1%C, in the wrought condition.

Due to the high aluminum and carbon content, there are unique challenges to large scale (45+ ton heat) production versus typical armor steel chemistries. Lab-scale wrought and production material are characterized, comparing microstructure, and mechanical properties. Processing practices including teeming flux and rolling temperature are discussed. The high manganese content of this alloy presents challenges for welding and machining practices, such as limited compatibility of weld wires and substantial work hardening during many basic fabrication operations. Mechanical property data and micrographs from initial gas metal arc welding and machining are presented and discussed.