提高20Mn2钢洁净度的关键技术

Critical technology of improving cleanliness of 20Mn2 steel

通过对20Mn2钢原有工艺的取样与现场数据分析，得出提高20Mn2钢洁净度的关键环节，包括转炉终点控制、精炼造渣、钙处理3方面。结合热力学的理论分析，得出3个环节的优化方案，分别包括转炉炉后控制过氧化现象，提高转炉终点叫（C）≥0．08％，并且控制终点础（P）≤0．015％；炉后加入铝矾土与调节石灰加入量对精炼渣进行改质，使渣系成分落在w（CaO）=50％～60％，w（A1203）=20％～40％，w（SiO2）=5％～10％，w（MgO）=5％；控制钙处理环节二次氧化，并将钙线的喂入长度控制在145~216m。对优化工艺进行工业试验得出，连浇炉数由5．9炉升高至14炉，钢中氧含量明显下降，夹杂物数量与尺寸减小。

Through analyses of samples and plant data, critical steps of improving clean- liness of 20Mn2 steel were obtained, and it included control of endpoint of converter, refining process and calcium treatment. Based on integrating thermodynamics and theo- retical analyses with practical process, optimized scheme including control of peroxidation at endpoint of converter by governing w（C）≥0. 08%, w（P）≤0. 015 %, modification of refining slag by adding bauxite and adjusting amount of CaO to limit composition of slag in the range of w（CaO）= 50%-60 %, w（Al2O3） = 20 %-40%,w（SiO2） = 5 %- 10 %,w（MgO） = 5 %, and domination of reoxidation and length of CaSi wire within 145 - 216 m was obtained. Industrial trials of optimized scheme showed that con- tinuous casting heats increased from 5.9 heats to 14 heats, oxygen content in steel declined dramatically, amount and dimensions of inclusions diminished.