【摘要】 针对国内某钢厂不锈钢板坯连铸生产过程中存在的宽面边部纵裂纹缺陷，通过实验室检测分析、连铸坯边部应力模拟等，揭示连铸坯宽面边部纵裂纹的形成机理。连铸坯边部纵裂纹附近晶粒粗大，原始奥氏体晶界处存在1层厚度从几十到上百微米的先析铁素体，裂纹主要沿着膜状先析铁素体开裂。连铸坯宽面边部纵裂纹内部检测到结晶器保护渣的特征元素Na，因此判定边部纵裂纹在结晶器内产生。距离弯月面大于0.2 m时，连铸坯宽面表面的应力值随着距边部距离的增加而增加，并在边部附近达到极大值，随后应力值逐渐降低并趋于稳定。连铸坯角部受到二维冷却产生较大凝固收缩导致间隙出现，使得角部冷却强度减弱，宽面侧靠近角部出现坯壳最薄点。由于凝固收缩使得靠近连铸坯边部附近存在应力的极大值，当结晶器锥度不能与凝固收缩完全匹配时，导致连铸坯宽面边部坯壳最薄处出现凹陷或裂纹。研究结果揭示了不锈钢连铸坯宽面边部纵裂纹的形成机理，为连铸坯表面缺陷控制提供理论依据。更多还原

【Abstract】 Longitudinal off-corner cracks on the wide face of stainless steel slabs were found in a domestic steel plant. The formation mechanism of longitudinal off-corner cracks on the wide edge of continuous casting slabs was revealed through laboratory testing and analysis, and stress simulation. The grains near the longitudinal off-corner cracks were coarse, and there was a layer of pre-precipitated ferrite with a thickness ranging from tens to hundreds of microns at the original austenite grain boundary, and the cracks mainly occurred along the filmy pre-precipitated ferrite. The characteristic element Na of the mold powder was detected inside the longitudinal off-corner cracks on the wide face of slabs, therefore it was determined that the longitudinal off-corner cracks were generated in the mold.When the distance from meniscus was greater than 0. 2 m, the stress on wide surface of continuous casting slab increased with the distance from corner. The maximum value was reached near the corner, and then the stress value gradually decreased and tended to be stable. The corners of continuous casting slab were subjected to twodimensional cooling, resulting in a large solidification shrinkage and led to the appearance of gaps, which weakened the cooling intensity of the corners and caused the thinnest point of the solidified shell to appear near corner on the wide face of slab. Due to the solidification shrinkage, there was maximum stress near the edge of continuous casting slab. When the taper of mold could not completely match the solidification shrinkage, depressions or cracks would appear at the thinnest point of solidified shell at the wide face edge of continuous casting slab. The formation mechanism of longitudinal off-corner cracks on the wide face of stainless steel slabs is revealed, and a theoretical basis for controlling surface defects in continuous casting slabs is provided.更多还原