| 摘要 |
PURPOSE:To obtain the titled seamless steel pipe having excellent low-temp. toughness and stress corrosion cracking resistance by working a seamless steel pipe having a prescribed component compsn. at and in a specified temp. range and reduction of area then cooling the steel pipe down to a room temp. to form martensitic structure and subjecting the steel pipe to a tempering treatment in a prescribed parameter range. CONSTITUTION:The seamless steel pipe of the martensitic stainless steel contg., by weight % 0.15-0.25% C, 0.20-1.00% Si, 0.20-1.00% Mn, <=0.030% P, <=0.0030% S, and 11.0-14.0% Cr is produced by a Mannesmann mandrel mill system. The steel pipe is then worked at 13-90% reduction of area in a 1,000-650 deg.C range in the final hot finishing stage at the time of the above-mentioned production. The steel pipe after said working is cooled down to the room temp. to form the martensitic structure and is then subjected to the tempering treatment to bring the tempering parameter defined by T(20+logt) (T; deg.K, t; time) in a 20,500-21,600 range. The seamless steel pipe of the martensitic stainless steel having the excellent low-temp. toughness and stress corrosion cracking resistance is thus obtd. |
