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结合生产实际,对断坯试样进行了光谱、低倍、扫描电镜(SEM)及能谱分析,分析认为:板坯内部裂纹是45号钢板坯横向脆断的根本内因,热坯缓冷速度过快造成板坯内部存在较大收缩应力或吊运过程中受到较大的机械外力是板坯横向脆断主要外因;同时,二次冷却不均匀影响柱状晶生长并造成元素偏析、疏松及夹杂物富集,是造成板坯内部裂纹的主要原因。
According to the actual production, the spectrum, low magnification, scanning electron microscopy (SEM) and energy spectrum analysis of broken billet were carried out. The analysis shows that the internal crack of billet is the fundamental internal cause of the transverse brittle fracture of 45 steel slab, Too fast to cause large shrinkage stress in slab or larger external mechanical force during hoisting, which is the main external cause of transverse brittleness of slab; meanwhile, the secondary cooling unevenly affects the growth of columnar crystal and causes element segregation, looseness and inclusion Material enrichment is the main reason for internal slab cracks.