High strength and resistance to high temperature and high chloride ion concentration wet carbon dioxide gas environment corrosive, stress corrosion cracking another excellent martensitic stainless steel and its manufacturing method

摘要

PURPOSE:To improve the corrosion resistance of the martensitic stainless steel in the atmosphere of wetting carbonic acid gas and to provide it with high cracking resistance to wetting hydrogen sulfide by austenitizing a stainless steel having specified compsn. at a specified temp., cooling it at a speed in air cooling or higher and thereafter executing tempering and cooling under specified conditions. CONSTITUTION:A martensitic stainless steel constituted of, by weight, 0.02 to 0.1% C, =1% Si, =2% Mn, 8 to 14% Cr, 1.2 to 4.5% Cu, 0.005 to 0.2% Al, 0.005 to 0.15% N and the balance Fe with inevitable impurities is refined. The steel is heated to about 920 to 1100 deg.C and is austenitized. Next, the steel is cooled at a cooling speed in air cooling or higher and is tempered at the temp. of 580 deg.C to Ac1 or below. Furthermore, the steel is cooled at a cooling speed in air cooling or higher. If required, one or more kinds among =4% Ni, =2% Mo and =4% W are incorporated into the steel.