Nonmetallic inclusion removal of Si-Mn deoxidized steel by nitrogen absorption and release method
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摘要: 以硅锰脱氧的SWRH82B热轧盘条为实验钢种，研究增氮析氮法对硅锰脱氧钢中夹杂物的去除效果，并设置0.02、0.035、0.05、0.065和0.08 MPa五组增氮压力进行热态实验.实验结果表明：在1873 K的温度下，钢液经过增氮20 min、真空处理30 min后，不同炉次钢中T[O]均下降至1×10-5以下，最低为4×10-6，T[N]均下降至5×10-6以下，最低为2×10-6，夹杂物去除率均为40%以上，T[O]去除率均大于78%，表明该技术对硅锰脱氧钢中的夹杂物及T[O]有良好的去除效果.此外，随着增氮压力的升高，钢中T[O]与夹杂物去除率均有所升高，当充氮压力为0.08 MPa时，T[O]与夹杂物去除率分别达到89.2%和87.4%.理论分析表明，随着增氮压力的升高，气泡形核率增大、钢中生成气泡数量增多、钢中气泡的密度增加，从而提升气泡去除夹杂物的效率.Abstract: The micro nonmetallic inclusion and oxygen content in steel significantly affect its performance, and removing the inclusion involves a difficult process. A nitrogen absorption and release method has been developed with which nonmetallic inclusions and T[O] were efficiently removed from bearing steel. However, the inclusions in bearing steel are highly different from those in Si-Mn deoxidized steel, and the effect of the nitrogen absorption and release method on the Si-Mn deoxidized steel remains unclear. Based on this, a thermal experiment was carried out in this study to investigate the removal of nonmetallic inclusions from Si-Mn deoxidized steel by nitrogen absorption and release method, where SWRH82B hot rolled wire coil was used as the experimental steel, and five groups of increasing nitrogen pressure (0.02, 0.035, 0.05, 0.065 and 0.08 MPa) were set up. The results show that for all groups, the T[O] and T[N] in the steel reduce to below 1×10-5 and 5×10-6, respectively, after the molten steel is subjected to 20 min of increasing nitrogen and 30 min of vacuum treatment. The lowest T[O] and T[N] in the steel is 4×10-6 and 2×10-6, respectively, and the inclusion removal rates for all the groups are more than 40%. The T[O] removal rates for all the groups are more than 78%.This result proves that nitrogen absorption and release method is efficient in removing inclusions and T[O] in Si-Mn deoxidized steel. Furthermore, the removal rate of inclusion and T[O] in the steel increases with the nitrogen pressure. When the nitrogen pressure is 0.08 MPa, the removal rates of T[O] and the inclusions are 89.2% and 87.4%, respectively. Theoretical analysis shows that the nucleation rate, number, and density of bubble in molten steel increase with pressure, the efficiency of the inclusions removal can be promoted.
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