Patent ID: 6312529
Filing Date: 2001-11-06
Classification: C21D,C22C,C23C

Abstract:
A method of processing high-nitrogen steels for optimizing the austenite grain coarsening resistance of cold-formed components during carburization, comprising the steps of:(a) providing a steel having a composition including a grain-refining addition,(b) reheating the steel at a temperature in the vicinity of a solution temperature of the least soluble species of grain-refining precipitate in the steel;(c) hot-working by finish rolling or forging the steel;(d) cooling the steel at an accelerated rate to 500.degree. C.;(e) subcritically annealing the steel at a temperature in a range from about 650.degree. C. to the A.sub.cl to produce a ferritic microstructure containing dispersed iron/alloy carbides and a dispersion of fine grain-refining precipitates;(f) subjecting the steel to at least one cold-forming operation with intermediate anneals to form a steel component;(a) subjecting the steel component to a subcritical anneal at a temperature in a range from about 600.degree. C. to the A.sub.cl after the last cold-forming operation to provide a ferritic microstructure containing dispersed iron/alloy carbides; and(h) carburizing, quenching and tempering the steel component.