含钒高氮高强耐候乙字钢大方坯连铸二冷技术

Research on Secondary Cooling Technologies for Bloom Continuous Casting of High Vanadium and Nitrogenous Weathering Steel

针对攀钢高强耐候乙字钢大方坯连铸二冷控制制度在连铸比水量和二冷区水量分配等方面存在的问题,通过采用延长喷水冷却区长度、适当增大连铸比水量、调整二冷区各回路的冷却能力及水量分配比例的方法,优化了YQ450NQR1大方坯连铸二冷制度。生产应用表明,高强耐候乙字钢大方坯内部质量明显提高,中心疏松评级≤1.0级的比例由79.71%增至90.70%,中心偏析<0.5级的比例由1.45%增至44.19%,无中心缩孔的比例由86.96%增至93.02%,无中心裂纹的比例由39.13%增至62.79%,无中间裂纹的比例由85.51%增至88.37%,无皮下裂纹的比例由78.26%增至97.67%,无角部内裂纹的比例由73.91%增至93.02%,为攀钢开发生产屈服强度450 MPa级高强度耐大气腐蚀乙字钢提供了高质量的铸坯。

Aim to optimize the secondary cooling scheme employed in continuous bloom caster for production of weathering steel for 310 Z - beam, which included the density of the secondary cooling and water distribution in secondary cooling zones, a series of improving measure was carried out. The improving measures include increasing the length of secondary cooling zones and the.specific water flow, adjusting the water flow distribution among the secondary cooling zones, so the optimum secondary cooling control scheme is developed, which improves internal quality of bloom 310 Z - beam obviously. The practical operation shows that the ratio of center looseness≤ 1.0 is increased from 79.71% to 90.70%, the ratio of central segregation 〈 0.5 is increased from 1.45% to 44.19%, the free central shrinkage cavity is increased from 86.96% to 93.02%, while, the free center line crack is increased from 39.13% to 62.79%, the free intermediate crack is increased from 85.51% to 88.37%, the free sub - surface crack is increased from 78.26% to 97.67%, and the free comer crack is increased from 73.91% to 93.02% ： The qualified blooms are delivered to produce 310 Z - beam which ReL is≥450 MPa.