大方坯凝固坯壳厚度的测定

Measurement of solidified shell thickness of continuous casting of bloom

为确定凝固末端电磁搅拌位置和二冷制度的优化提供可靠的依据,利用"射钉法"对某钢厂大方坯典型钢种42CrMo和GCr15在工作拉速下凝固坯壳的厚度进行了测定。根据凝固理论计算铸坯综合凝固系数,测定出连铸机二冷区域凝固坯壳的厚度及凝固终点的位置,获得了凝固终点位置及凝固系数和拉速的关系。结果表明:铸机拉速0.45～0.5m/min时,42CrMo二冷区综合凝固系数为25.34～26.44mm/min1/2,液相穴长度19～23 m;铸机拉速0.42～0.45 m/min时,GCr15二冷区综合凝固系数为25.24～26.45mm/min1/2,液相穴长度18～21m。同时,验证了二级专家系统的准确性。

In order to provide a reliable basis for confirming the final electromagnetic stirring position and improving the secondary cooling system, the measurement is carried out by using the pin-shooting technique for bloom solidified shell thickness of two types of steel 42CrMo and GCr15. According to solidification theory, the slab composite solidification coefficient is calculated, which can more accu- rately determine the solidified shell thickness in secondary cooling system and frozen final position of bloom continuous casting, and the relationship between the coefficient of solidification and casting speed is obtained. The results show that： when the casting speed is 0.45-0.50 m/min, the compos- ite solidification coefficient of 42CrMo in secondary cooling zone is 25.34 - 26.44 mm/min1/2 , the length of liquid core is 19-23 m. When the casting speed is 0.42-0.45 m/min, the composite solidi- fication coefficient of GCr15 in secondary cooling zone is 25.24-26.45 mm/min1/2 , the length of liq- uid core is 18-21 m. Simultaneously, the accuracy of second level expert system is verified.