METASTABLE AUSTENITE PHASE IN RAPIDLY QUENCHED Fe-CR-C.

Abstract

Metastable austenitic alloys with high strength and hardness have been found. The formation range is limited to about 1. 0 2. 2wt%C and 7 30wt%Cr. The austenite phase has ultra-fine grains of about 0. 2 mu m in diameter. The Vickers hardness, 0. 2% proof stress and tensile fracture strength increase with carbon and chromium, and maximum values reach about 630 DPN, 1 500 and 1 500 MPa, respectively. These alloys are so ductile that no crack is observed even after closely contacted bending. Secondary hardening occurs at about 870 K due to phase transformation from austenite to equilibrium structures of ferrite and M//7C//3 pearlite. The alloys may be attractive as fine gauge high-strength wire or plate.