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针对某厂用氧气顶吹转炉—LF精炼—连铸生产的40Cr连铸坯内部角裂,通过对生产工艺流程、连铸机设备分析,采用热酸侵低倍试验、金相法和探针能谱分析对缺陷进行研究,发现缺陷不存在组织异常和质点沉淀现象。通过运用ANSYS软件对连铸结晶器凝固过程进行热模拟,发现角裂形成于结晶器内的凝固过程,根本原因是铸坯在结晶器凝固过程的传热特性产生明显热节区甚至在铜管使用后期伴随出现鼓肚,从而诱导产生应力使铸坯近角部热节区成为裂纹易发区。确定缺陷涉及钢水成分、连铸工艺参数及铜管圆角不适,最终通过对生产工艺参数的严格控制和结晶器铜管圆角半径的优化设计,使1.0级以下内部角裂的控制在89.68%以内。
Aiming at the internal corner cracking of 40Cr slab produced by oxygen top-blown converter-LF refining and continuous casting in a factory, through the analysis of production process, equipment of continuous casting machine, the test of thermal acid intrusion, the metallographic method and the energy spectrum Analysis of defects in the study found that defects do not exist abnormal tissue and sedimentation phenomenon. By using ANSYS software to simulate the solidification process of continuous casting mold, it is found that the corner crack forms in the solidification process of the mold. The fundamental reason is that the heat transfer characteristics of the slab during the solidification of the mold produce obvious hot joints, With the late use of bulging belly, which induces stress so that the near-corner hot slab slab cracks prone areas. Determine the defects related to the composition of molten steel, continuous casting process parameters and copper pipe fillet discomfort, and finally through the strict control of the production process parameters and mold copper tube radius optimization design so that the internal control below 1.0 fissure control 89.68% Within.