连铸板坯热轧中角部裂纹变化的研究

THE CRACKS ON SLAB CORNER DURING HOT ROLLING PROCESS

采用有限元方法对轧件角部横向和纵向裂纹在多道次立-平轧制过程中变形行为进行了模拟,分析了裂纹的闭合与扩展行为．结果表明:采用平立辊,裂纹很好闭合,但变形程度大,可能延伸和往轧件顶面移动,对角部横向裂纹,裂纹尖端节点往外扩散,对三角形横向和纵向裂纹,裂纹可能发生折叠;采用孔型立辊,立轧后,轧件裂纹很好地闭合,平轧后,横向和侧面纵向裂纹可能被拉开,顶面纵向裂纹闭合较好,只有三角形横向裂纹可能发生折叠．

The slab corner surface transversal cracks and longitudinal cracks during a multi-pass V-H rolling process with plain-barreled vertical roll and shape vertical roll were simulated by the explicit dynamic finite element method and updating geometric method, and the effects of vertical roll shape during rolling process on crack closure and growth were analyzed. Results show that, when applying plain-barreled vertical roll during multi-pass V-H rolling process, the deformation of slab corner crack is large, and it tends to spread, for slab corner transversal cracks, the nodes on crack tip lines may diffuse outwards, for triangle transversal cracks and longitudinal cracks, one side of crack may be folded; when applying shape vertical roll during multi-pass V-H rolling process, after vertical rolling, the cracks are closed well, after horizontal rolling, the longitudinal cracks and transversal cracks on slab side surface may open again, but the transversal cracks on slab top surface can be closed well, at the same time, only triangle longitudinal cracks show the phenomenon that one side of crack is folded.