优化连铸工艺和化学成分改善耐蚀钢G7624表面质量的生产实践

高合金耐蚀钢G7624(/%:≤0.08C,≤0.75Si,11.5~13.5Mn,≤0.045P,≤0.010S,13.0~14.0Cr,0.5~1.0Ni,1.5~2.0Cu,0.160~0.210N)Φ5.5 mm线材的生产流程为45 t脱磷铁水-(50 t EAF)-60 t AOD-LF-150mm×150 mm方坯连铸-修磨-轧制工艺。通过使用BHCD-200M低熔点、低黏度保护渣,结晶器冷却水量从1750~1850 L/min降至1600~1700 L/min,由二冷段单排水嘴改进为双排小锥度并行水嘴,比水量由0.25 L/t降至0.22L/t,消除了连铸坯的表面凹陷;将钢中C、Mn、N含量分别由0.064%,11.56%和0.195%调整至0.073%,12.45%和0.170%,提高钢中奥氏体稳定性,消除线材结疤缺陷。

Production Practice of Improving Surface Quality of Corrosion Resistant Steel G7624 by Optimizing Concasting Parameters and Chemical Composition

The production flow sheet for 5. 5 mm wire rod of high alloying corrosion resistant steel G7624 ( /% : ≤ 0.08C, ≤ 0.75Si, 11.5~13.5Mn, ≤ 0.045P, ≤ 0.010S, 13.0-14.0Cr, 0.5-1.0Ni, 1.5-2.0Cu, 0.160-0.210N) is 45 t dephosphorized metal-(50 t EAF)-60 t AOD-LF-150 mm x 150 mm billet concasting-grinding-rolling process. With using BHCD-200M low melting point and low viscosity shielding powder, decreasing mold cooling water rate from 1750-1850 L/min to 1600-1700 L/min, adjusting secondary cooling zone with single row water nozzles to double rows small cone angle and parallel water nozzles, and decreasing water rate from 0.25 L/t to 0.22 L/1, the surface depression defect of concasting billet is eliminated； with adjusting C, Mn, N content in steel respectively from 0.064% , 11.56% and 0.195% to 0.073% , 12.45% and 0.170% to increase the stability of austenite in steel, the scab defect of wire rod is also eliminated.