Patent ID: 6273968
Filing Date: 2001-08-14
Classification: C21D,C22C

Abstract:
A process for manufacturing a high-strength, corrosion-resistant, tough alloy carbon steel, comprising:(a) forming an alloy composition consisting of iron and at least one alloying element comprising carbon in proportions selected to provide said alloy composition with a martensite transition range having a martensite start temperature M.sub.s of at least about 350.degree. C., said proportions further selected to permit air-cooling of said alloy composition through said martensite transition range without forming carbides;(b) heating said alloy composition to a temperature sufficiently high to cause austenitization thereof, under conditions causing said alloy composition to assume a homogeneous austenite phase with all alloying elements in solution; and(c) cooling said homogeneous austenite phase through said martensite transition range at a cooling rate sufficiently fast to avoid the occurrence of autotempering, to achieve a microstructure containing laths of martensite alternating with films of retained austenite and containing substantially no carbides.