| 摘要 |
PURPOSE:To manufacture efficiently the titled stainless steel pipe superior in high temp. characteristic, by heat treating and hot extruding a steel billet having a specified compsn. composed of C, Si, Mn, Cr, Ni, Nb, B, N and Fe. CONSTITUTION:The billet of steel composed of, by weight, 0.04-0.12% C, 0.1-0.8% Si, <=2% Mn, 15-25% Cr, 9-20% Ni, <=1% Nb under 8-12 Nb/C wt. ratio, <=0.005% B under B>=0.001X(Nb/C)-0.01%, 0.005-0.100% N, as impurities <=0.02% P, <=0.006% S under P+0.04XSi<=0.035%, if necessary, further 0.01-2.5% Mo and the balance Fe with inevitable impurities is heated to enter carbide into solid soln. and cooled at >=0.3 deg.C/sec average rate until 500 deg.C. Then, the billet is hot extruded at >=1,100 deg.C, then cooled rapidly to prevent coarse carbide ppt., to obtain austenitic stainless steel pipe having fine grain structure, superior high temp. corrosion resistance, and creep rupture strength.
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