Abstract: A high strength, low alloy, low to medium carbon steel casting is provided of the Fe/Cr/C type containing by weight about 0.1 to 0.5% Si, said steel characterized by the presence of a small but effective amount of each of Cu and Ni sufficient to enhance the mechanical stability of retained austenite formed following quenching of said steel from its austenitizing temperature, the amount of Ni being at least sufficient to counteract the destabilizing effect of Si on austenite. Preferably the steel also includes small but effective amounts of Al, Ti and Nb sufficient to provide a fine grained microstructure.

Abstract: A microalloy-free, high strength, low alloy, low carbon, manganese steel characterized by a dual phase microstructure wherein acicular retained austenite particles are distributed within a ferrite matrix. The ferrite-austenite microstructure is produced by a heat treatment comprising heating the steel above the upper critical austenite transformation temperature to produce an austenite microstructure; quenching to produce a lath martensite microstructure; tempering at a temperature below the lower critical austenite transformation temperature to partition carbon and manganese to form cementite particles and to transform the martensite to ferrite, thereby producing a microstructure comprising cementite particles dispersed within a ferrite matrix; annealing at an intercritical temperature to decompose the cementite and produce austenite particles; and quenching to retain the austenite particles within the ferrite matrix.

Abstract: A high strength, tough alloy steel, particularly suitable for the mining industry, is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other subsitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

Abstract: A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.