VIBRATION-DAMPING FERRITIC STAINLESS STEEL MATERIAL, AND PRODUCTION METHOD
A ferritic stainless steel material excellent in vibration damping capability has a composition containing, by mass %, from 0.001 to 0.03% of C, from 0.1 to 1.0% of Si, from 0.1 to 2.0% of Mn, from 0.01 to 0.6% of Ni, from 10.5 to 24.0% of Cr, from 0.001 to 0.03% of N, from 0 to 0.8% of Nb, from 0 to 0.5% of Ti, from 0 to 2.0% of Cu, from 0 to 2.5% of Mo, from 0 to 1.0% of V, from 0 to 0.3% of Al, from 0 to 0.3% of Zr, from 0 to 0.6% of Co, from 0 to 0.1% of REM, from 0 to 0.1% of Ca, the balance of Fe and unavoidable impurities, and has ferrite single phase matrix with crystal grains of average crystal grain diameter of from 0.3 to 3.0 mm and a residual magnetic flux density of 45 mT or less.
1 . A vibration-damping ferritic stainless steel material having a chemical composition containing, in terms of percentage by mass, from 0.001 to 0.03% of C, from 0.1 to 1.0% of Si, from 0.1 to 2.0% of Mn, from 0.01 to 0.6% of Ni, from 10.5 to 24.0% of Cr, from 0.001 to 0.03% of N, from 0 to 0.8% of Nb, from 0 to 0.5% of Ti, from 0 to 2.0% of Cu, from 0 to 2.5% of Mo, from 0 to 1.0% of V, from 0 to 0.3% of Al, from 0 to 0.3% of Zr, from 0 to 0.6% of Co, from 0 to 0.1% of REM (rare earth element), from 0 to 0.1% of Ca, and the balance of Fe, with unavoidable impurities, having a metal structure containing a ferrite single phase as a matrix and ferrite crystal grains having an average crystal grain diameter of from 0.3 to 3.0 mm, and having a residual magnetic flux density of 45 mT or less.
2 . The vibration-damping ferritic stainless steel material according to claim 1 , wherein the steel material has an oxidation increase in quantity of 2.5 mg/cm 2 or less on retaining at 900° C. in the air for 200 hours.
3 . A production method for a vibration-damping ferritic stainless steel material, comprising subjecting a steel material having a chemical composition containing, in terms of percentage by mass, from 0.001 to 0.03% of C, from 0.1 to 1.0% of Si, from 0.1 to 2.0% of Mn, from 0.01 to 0.6% of Ni, from 10.5 to 24.0% of Cr, from 0.001 to 0.03% of N, from 0 to 0.8% of Nb, from 0 to 0.5% of Ti, from 0 to 2.0% of Cu, from 0 to 2.5% of Mo, from 0 to 1.0% of V, from 0 to 0.3% of Al, from 0 to 0.3% of Zr, from 0 to 0.6% of Co, from 0 to 0.1% of REM (rare earth element), from 0 to 0.1% of Ca, and the balance of Fe, with unavoidable impurities, to final annealing in a non-oxidative atmosphere under a condition of retaining the steel material in a temperature range of from 900 to 1,250° C. for 10 minutes or more, so as to make an average crystal grain diameter of ferrite crystal grains of from 0.3 to 3.0 mm, and then cooling to a temperature of 200° C. or less at a maximum cooling rate of from a maximum attaining material temperature to 200° C. of 5° C./sec or less and an average cooling rate of from 850° C. to 400° C. of 0.3° C./sec or more.
4 . The production method for a vibration-damping ferritic stainless steel material according to claim 3 , wherein the final annealing is performed in an air atmosphere instead of the non-oxidative atmosphere, and acid cleaning is performed after the final annealing.
5 . The production method for a vibration-damping ferritic stainless steel material according to claim 3 , wherein the steel material subjected to the final annealing is a steel material obtained by working a steel sheet material.
6 . The production method for a vibration-damping ferritic stainless steel material according to claim 3 , wherein the steel material subjected to the final annealing is a steel material having a chemical composition providing an oxidation increase in quantity of 2.5 mg/cm 2 or less on retaining at 900° C. in the air for 200 hours.