| 摘要 |
PURPOSE:To obtain a martensitic stainless steel having a low ductility-brittleness transition temp. by making the structure of a martensitic stainless steel fine by recrystallization induced by hot working and by regulating the cooling rate so as to prevent the precipitation of carbide at the grain bundaries. CONSTITUTION:A martensitic stainless steel is heated to about 1,100-1,250 deg.C and subjected to hot working such as rolling or forging at >= about 50% working rate. The working is finished at a temp. above the recrysallization starting temp., preferably at about 950-1,050 deg.C, and the temp. of the steel is kept until recrystallization is finished. The steel is slowly cooled to about 900 deg.C while intermittently keeping the temp. as required, and it is rapidly cooled, cooled with an air blast or allowed to cool to about 900-600 deg.C at a cooling rate below the nose so as to avoid the precipitation of carbide. Thus, a martensitic stainless steel with stabilized toughness is obtd. |
