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钢板表面微裂纹严重影响产品质量。通过微裂纹特征分析、观察铸坯和钢板金相及能谱(EDS)检测、梳理生产过程参数,得出Q345A(厚)钢板表面微裂纹产生的主要原因是连铸结晶器铜板镀层脱落。这一方面会导致铜渗透入坯壳的奥氏体晶界,产生晶界裂纹;另一方面会因热应力不均而产生裂纹,并在含钛等裂纹敏感性强的钢中表现尤其明显。控制措施为:提高结晶器铜板质量,杜绝露铜;加强生产前对镀层铜板和生产后铸坯质量的检查;通过做好保护浇注等措施,提高钢水洁净度。
Micro-cracks on the steel surface seriously affect the product quality. The microcrack character analysis was used to observe the metallurgical and energy spectrum (EDS) of slab and plate, and the parameters of the production process were analyzed. The main reason for the microcrack on the surface of Q345A (thick) steel plate was the loss of the copper plate coating of continuous casting mold. On the one hand, it leads to the infiltration of copper into the austenite grain boundaries of the shell and to grain boundary cracks, on the other hand cracks due to uneven thermal stresses and is particularly pronounced in steels with high crack susceptibility, such as titanium . Control measures are: to improve the quality of copper mold, eliminate copper exposed; to strengthen the pre-production of copper plate after the production and inspection of the quality of slab; through the protection of pouring and other measures to improve the cleanliness of molten steel.