STEEL FOR ULTRA-SUPERCRITICAL THERMAL POWER UNIT AND PREPARATION METHOD THEREFOR

摘要

A steel for an ultra-supercritical thermal power unit and a preparation method therefor, the steel having the following chemical components by mass percent: Cr: 8.0-10.0%; W: 2.0-3.2%; Co: 2.0-4.0%; V: 0.1-0.3%; Nb: 0.01-0.1%; B: 0.006-0.018%; Cu: 0.2-1.0%; Mn: 0.2-1.0%; Al: 0.005-0.08%; Si: 0.1-0.8%; C: 0.06-0.12%; N: 0.003-0.010%; P: ≤0.02%; S: ≤0.01%; Ni: ≤0.01%; Re: ≤0.01%; Ti: ≤0.01%; and the balance of Fe and unavoidable impurities. The total amount of the unavoidable impurities is ≤0.015%, and the components also need to meet: 1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2, and 0.6≤B/N≤6. The steel has good resistance to steam corrosion oxidation and a good long-lasting high temperature creep performance, wherein the performance is specifically that the creep rupture strength at 620-650°C for 100,000 hours is not less than 100 MPa by extrapolation; the weight gain is not greater than 18mg/cm² after steam oxidation corrosion at 650°C for 1000 hours. The present invention is especially suitable for boiler tubes or other heat-resistant equipment of the ultra-supercritical thermal power unit.