Relationship between microstructures and tensile properties of an Fe-30Mn-8.5Al-2.0C Alloy

Abstract

Owing to the presence of a large amount of fine (Fe.Mn)3 A1C carbides within austenite (γ) matrix, the tensile property of the Fe-30%Mn-8.5A1%-2.0%C (in mass%) alloy in the as-quenched condition was clearly superior to that of the as-quenched FeMnAlC (C ≤ 1.3%) alloys investigated by previous workers. After being aged at 823 K for 3 h, the present alloy could possess high yield strength up to 1262 MPa with an excellent 32.5% elongation. With almost equivalent ductility, the yield strength obtained was about 16% higher than that of the FeMnAlC (C ≤ 1.3%) alloys after solution heat-treatment or controlled-rolling followed by an optimal aging at 823 K. Additionally, due to the pre-existing fine (Fe,Mn)3 A1C carbides within the y matrix in the as-quenched alloy, the aging time required for attaining the optimal combination of strength and ductility was much less than that of the FeMn)AlC (C ≤ 1.3%) alloys aged at 823 K. When the present alloy was aged at 823 K for a time period longer than 4 h, both the strength and ductility were drastically dropped due to the occurrence of γo/ k(γo: carbon-deficient austenite) lamellar structure on the γ/γ grain boundaries. ©2010 The japan Institute of Metals.