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高速铁路对重轨钢质量提出了更高的要求,洁净度与均质性控制是其质量提升的关键。包钢高速重轨钢采用无铝脱氧工艺降低钢水全氧质量分数、VD真空脱气工艺强化脱氢、全程保护浇注与中间包冶金防止钢水二次氧化和促使钢中夹杂物上浮,提高钢的洁净度;通过合理控制钢液过热度、严格控制拉速、采用结晶器电磁搅拌、动态二冷、动态轻压下控制等关键技术来减轻和消除铸坯中心偏析,提高钢的均质性。生产实践表明,高速重轨钢中w T[O]≤0.002 0%、w[N]≤0.005 0%、w[H]≤0.000 15%、w[Al]≤0.004 0%,A类夹杂物不超过2.0级,B、C、D类夹杂物不超过1.0级,中心疏松评级不超过1.0级的比例平均为83.1%,中心缩孔不超过0.5级的比例平均为94.3%,中心碳偏析指数最大为1.07。包钢高速重轨钢综合质量满足了《时速200km客运专线铁路用钢轨标准》的要求。
High-speed railway put forward higher requirements on the quality of heavy rail steel, and the control of cleanliness and homogeneity is the key to its quality improvement. Baotou Steel high speed heavy rail steel with aluminum-free deoxidation process to reduce the oxygen content of molten steel, VD vacuum degassing technology enhanced dehydrogenation, full protection of casting and tundish metallurgy to prevent secondary oxidation of molten steel and to promote inclusions in steel to raise the steel Cleanliness; through the reasonable control of molten steel superheat, strict control of casting speed, the use of mold electromagnetic stirring, dynamic cooling, dynamic soft reduction and other key technologies to reduce and eliminate slab center segregation and improve steel homogeneity. Production practice shows that in high-speed heavy rail steel w T [O] ≤0.002 0%, w [N] ≤0.005 0%, w [H] ≤0.000 15%, w [Al] ≤0.004 0%, Class A inclusions No more than Grade 2.0, Class B, C, D inclusions not exceeding 1.0 grade, center loose grade not exceeding 1.0 grade average 83.1%, center shrink no more than 0.5 grade average 94.3%, center carbon segregation index The maximum is 1.07. The comprehensive quality of Baotou Steel high-speed heavy rail steel meets the requirements of “rail standard for railways with a speed of 200km per passenger dedicated line”.