Mechanism analysis and control on corner crack for Q235 continuous casting slab
To solve the corner crack of the Q235 continuous casting slab,the cause of the defect formation was studied by combining the analysis of the microstructure of the defect and the statistical analysis of the influence law of the process parameters.The results show that a large amount of AlN precipitation before straightening was the main reason for the occurrence of corner cracks.Based on the thermodynamic analysis of AlN precipitation,with the aluminum content and nitrogen content decreasing,the initial precipitation temperature of AlN decreases,and the amount of AlN precipitation significantly decreases during the straightening temperature range.Based on production control,aluminum reduction measures have been determined as a control measure to improve corner cracks in the casting slab.After the on-site application of aluminum reduction measures,the corner crack index of the Q235 continuous casting slab decreased from 3.59 to 0.19,the mass fraction of the average aluminum in steel decreased by 126.64 × 10-4％,and the alloy use cost was decreased.
peritectic steelslabcorner crackAlN precipitationaluminum reduction control
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