FERRITIC FREE-CUTTING STAINLESS STEEL EXCELLENT IN COLD WORKABILITY, TOUGHNESS, CORROSION RESISTANCE, AND MACHINABILITY AND ITS PRODUCTION

摘要

PURPOSE:To inexpensively produce a ferritic free-cutting stainless steel excellent in cold workability, toughness, corrosion resistance, and machinability by applying specific hot working to a low-carbon steel stock having a specific composition containing Cr, Mo, Pb, etc. CONSTITUTION:A steel stock which has a composition consisting of, by weight, =0.020% C, =0.30% Si, =0.50% Mn, =0.020% P, 16.0-25.0% Cr, =1.0% Cu, =1.0% Ni, =3.0% Mo, =0.010% O, =0.025% N, =0.040% (C+N), 1-20% Nb/(C+N), further one or more kinds among =0.20% Pb, =0.10% Bi, and =0.15% Se, and the balance Fe with impurities and containing, if necessary, 0.03-0.50% Ti and/or 0.03-0.50% Zr is subjected to hot working at =1000 deg.C at =80% draft. By this method, the ferritic free-cutting stainless steel having superior corrosion resistance comparable to that of SuS304, less expensive than SuS304, and excellent in cold workability, toughness, and machinability can be obtained.