150t精炼钢水包耐火层热-机械耦合应力分析

Analysis of thermo-mechanical coupling stress of refractory layer of 150 t refining ladle

对设计建造的某厂150 t精炼钢水包,采用非线性有限元分析方法,建立了钢水包座包过程的三维接触模型。在温度场和热载荷分析的基础上,建立了耐火层的热-机械耦合应力分析的力学模型,并进行了相应的计算。计算结果表明,钢包壁部分的强度符合要求,不会引起开裂漏钢事故。而对耐火层的计算表明,耐火层包底热-机械耦合应力虽然最大,但由于处于压应力状态,尚没有超过耐材的抗压强度,包底耐火层出现开裂的可能性不大。在耳轴箱部位的耐火层的热-机械耦合应力虽然不是最大,但该区域处于拉应力主导状态,在内壁和外壁的应力幅值均已达到或超过耐材的抗折强度,容易产生沿壁厚方向的贯穿性裂纹,引发漏钢事故。根据计算结果,采用降低相对变形的技术方法,降低了耳轴箱部位耐火层的应力幅值,有效地解决了大吨位、大容积比钢水包上部耐火层漏钢的技术问题。

By the use of the nonlinear finite element method, a three dimensional contact model was built for the sitting process of a 150 ton refining ladle. A mechanical model for analyzing the thermo-mechanical coupling stress of the refractory layer was established on basis of the analyses of the temperature field and thermal load. The thermo-meehanieal stress field was calculated. The result shows that the steel wall of the ladle has enough strength to avoid cracking. The thermo-mechanical stress field shows that the bottom of the refractory layer is under the compress stress state and has the maximum stress but its stress has not exceeded over the ultimate compression stress. Hence, the crack does not take place. However, the refractory layer of the trunnion box is under tensile stress state, and has the thermo-mechanical stress over the bending ultimate stress either at the in- ner or at outer wall. Such a stress distribution will result in crack throughout the whole wall. The crack can lead the leakage of molten steel. According to the investigation by the calculations, a technique to reduce the relative deformation was adopted to reduce the thermo-mechanical stress of the refractory layer of the ladle behind the trunnion box. It is successfully applied to solving the problem of molten steel leakage of the large tonnage and large volume ratio ladle.