异型坯表面横裂纹的控制技术

Surface Transversal Crack Control Technology for Beam Blank

马钢连铸异型坯在生产耐候钢时存在表面横裂纹,造成轧后废品。通过对结晶器热模拟分析,对连铸坯热成像温度分析,异型坯翼缘顶端至腹板存在较大的温度梯度,特别是翼缘顶端到腹板角部,无法避开高温脆性区。450 MPa级耐候H型钢含有一定的Cu、V、N、Al,晶界析出大量低熔点物质造成钢的高温延展性降低。经过改进,连铸坯温度差减小,设备精度提高,钢中低熔点物质得到控制,抑制了横裂纹的发生。

There was surface transversal cracks on the continuous casting beam blank when producing weathering steel in Ma-Steel company, causing rolling waste. Thermal simulation analysis of mould and the thermal imaging temperature analysis of continuous casting billet were carried out. It is found that there are large variations in surface temperature of beam blank, especially from tip to web; the high temperature brittle zone can not be avoided. There are certain amounts of Cu, V, N and Al in the 450 MPa grade weathering steel and low melting point material precipitated on grain boundaries, leading to high temperature ductility decreasing. After improvement, variations in surface temperature of beam blank are reduced, equipment accuracies are improved, low melting point material is decreased, and then the surface transversal cracks are controlled.