钛稳定化321奥氏体不锈钢EAF-AOD-LF-板坯连铸的生产工艺实践

Process Practice of Titanium Stabilizing Austenite Stainless Steel 321 Produced by EAF-AOD-LF-Slab Casting

钛稳定化321奥氏体不锈钢(/%:0.04～0.08C,0.40～0.70Si,0.80～1.50Mn,≤0.035P,≤0.005S,17.0～18.0Cr,9.0～9.5Ni,0.20～0.40Ti,≤0.020 0N)的生产流程为90tEAF-45t AOD-LF-180mm×1 238 mm板坯连铸。该钢在浇铸过程中易产生水口结瘤和结晶器钢水中出现"结鱼"。根据TiN析出规律的分析,得出为降低TiN在钢水中的析出,应控制[N]≤0.015 0%,[Ti]≤0.25%,中间包钢水温度～1500℃。通过AOD全程采用超纯Ar搅拌,钢包中渣层厚度150 mm,[0]为15×10^(-6)～20×10^(-6),控制[N]～110×10^(-6),采用碱度0.75,1300℃粘度0.165 Pa·s的保护渣等工艺措施,使Ti回收率由原40%提高到52%,成品N含量由0.0140%降至0.010 5%,浇铸结束后水口内径由42 mm增至50 mm,轧制缺陷率由改进前3.5%降至1.2%。

The production flowsheet of titanium stabilizing austenite stainless steel 321 （/% ： 0. 04 - 0. 08C, 0.40 0.70Si,0.80～1.50Mn, ≤0.035P, ≤0.005S, 17.0 ～18.0Cr, 9.0～9.5Ni, 0.20 ～0.40Ti,≤0.0200N） is 90t EAF-45 t AOD-LF-180 mm × 1 238 mm slab casting. The ＂floater＂ in liquid of steel in mold occurs and the nozzle blocking produces in casting process. Based on analysis on TiN precipitation rule it is obtained that in order to decrease of TiN precipitation in liquid it should be controlled [ N ]≤ 0. 015 0%, [ Ti ] ≤0. 25% and temperature of liquid in tundish ～ 1 500 ℃. With process measures including using extra-pure Ar stirring in whole AOD process, controlling ladle slag thickness 150 mm, [ O ] 15 ×10 ^-6 ～20 × 10^ -6 and [ N ] ～ 110 × 10 ^-6, and using shielding slag with basicity 0. 75 and viscosity 0. 165 pa · s at 1 300 ℃, the yield of Ti increases from original 40% to 52%, the N content in finished liquid decreases from 0. 014 0% to 0. 010 5% , the inner diameter of nozzle at finished casting increases from original 42 mm to 50 mm, and the defect of rolled products decreases from original 3.5% to 1.2%.