HIGH STRENGTH* COLD PLASTICCSHAPED STEEL OF VERY HIGH DURABILITY AND CREEP RESISTANCE* AND MANUFACTURE THEREOF

摘要

PURPOSE:To provide steel of high strength, durability and creep resistance, which is used for shaping, by subjecting a carbon steel material successively to high speed heating, hardening, high speed heating to a temp. at which it is kept for a short time, then to cold plastic working, reheating, and tempering at a low temp. CONSTITUTION:A steel material contg. C not less than 0.3 % is heated at a high rate by high frequency induction heating etc., and is hardened. It is then heated at a high rate to 300-600 deg.C, and is kept at the temp. for, e.g., 60 secs., thereafter cooled with water etc. The steel is cold plastic worked and reheated to 300-500 deg.C, then tempered at a low temp. to remove the residual stress due to the cold working. Hereby, works such as coil springs having simultaneously high strength, high dur ability, and high creep resistance are manufactured.