【作者】 王青峡；

【导师】 陈登福；

【作者基本信息】 重庆大学 ， 冶金工程， 2008， 硕士

【摘要】 连铸是炼钢生产中的重要环节。连铸过程中,铸坯不同位置处凝固壳厚度的变化规律对生产工艺的改进有重要意义,同时,对坯壳应力应变状态的分析有助于深入的认识连铸工艺对铸坯质量的影响。本论文采用射钉法对新疆八一钢铁有限公司连铸钢种Q235和Q345B的凝固壳厚度进行了测试。测试的纵向位置选取连铸机水平段的四个位置,横向选取在铸坯断面的1/2、1/4和1/8处,获得了不同工艺条件下的凝固壳厚度。利用测试结果,计算凝固终点位置,并分析凝固壳厚度的变化规律。分析表明,该铸机的冷却强度较大,拉速为1.2m/min时,Q235钢的凝固终点位置在20m-21m之间;拉速为1.3m/min时,Q345B钢的凝固终点位置在23m-25m之间。测试研究为优化工艺参数、提高连铸机生产效率和有效实施动态轻压下奠定了基础。依据八钢连铸机的结构参数,采用MSC.Marc有限元分析软件,建立了从结晶器弯月面至水平段末端的纵向二维平面模型。利用凝固壳厚度测试结果对传热模型的边界条件进行修正,计算获得了Q235钢连铸板坯的纵向二维温度场。通过调用计算的温度场对连铸板坯纵向二维应力变化进行数值模拟,获得了铸坯不同位置处的应力应变分布。通过比较,模拟计算结果与现场实测的铸坯表面温度和坯壳厚度基本吻合。同时,将计算所得的连铸坯收缩值与铸机的辊缝收缩设定值进行了比较,得到模拟计算的收缩值与设定值之间的误差小于±0.2mm。因此,论文建立的计算模型对评价不同冷却制度下的辊缝收缩量有重要的价值。通过分析不同位置处的温度场和应力场,结果表明,铸坯表面等效热应力的最大值出现在结晶器出口附近,内部中心位置在凝固初期的等效热应力变化值较小,但在凝固末端由于温度的急剧降低,等效热应力值迅速增加。因此,保证铸坯的均匀冷却,减小温度波动所引起的等效热应力应变值,对改善铸坯质量有重要作用。更多还原

【Abstract】 Continuous casting is key link in steel making. During the continuous casting process, change law of solidified shell thickness have had a significant impact to improve production process, meanwhile, analyzing state of stress and strain to help to in-depth know continuous casting process on the quality of impact.In this paper, solidified shell thickness of steel Q235 and Q345B had been tested for Xinjiang Bayi Iron and Steel Company by nail-shooting method. Four position of horizontal section are selected along the longitudinal direction, three position (1/2, 1/4and1/8) are selected along lateral position, obtained solidified shell thickness under different cooling process. By test results, end of solidification had been calculated, and analyzing change law of solidified shell thickness. Analysis shows that, cooling intensity of caster is greater, end point of solidification is approximately 20m-21m when casting speed is 1.2m/min for Q235, end point of solidification is approximately 23m-25m when casting speed is 1.3m/min for Q345B. Testing research may lay the foundation for optimizing parameters and improving efficiency and implementing dynamic soft reduction.In accordance with structural parameters of BA steel caster, adopted MSC.Marc Finite-Element software, established longitudinal two-dimensional plane model from meniscus to outlet of horizontal section. Boundary conditions of heat transfer model had been modified by test result of solidified shell thickness, obtained two-dimensional temperature field of steel Q235 slab continuous casting. Simulated longitudinal two-dimensional stress changes for slab continuous casting by using calculated temperature field, obtained different position stress-strain distribution. By comparing, the simulation results consistent with test results of slab surface temperature and solidified shell thickness. At the same time, calculated slab shrinkage comparison with the roll gap reduction settings of caster, obtained calculation and settings among the error is less than±0.2mm. Therefore, paper model has important value for evaluating of different cooling technology of roll gap shrinkage.By analyzing different position temperature field and stress field, the results show that maximum of surface equivalent thermal stress is the outlet of mold, equivalent thermal stress is less in early solidification for center position, because of temperature decreasing of end point, equivalent thermal stress increased rapidly. Therefore, ensure uniform cooling of continuous casting, reduce equivalent thermal stress and strain caused by changes of temperature, have had significant impacts to improve quality of continuous casting.更多还原