共查询到17条相似文献,搜索用时 140 毫秒
1.
2.
3.
4.
5.
以低碳钢和中碳钢为研究对象,围绕不同连铸工艺参数对方坯初始凝固行为的影响,利用CA-FE耦合模型模拟实际连铸过程结晶器内方坯的初始凝固行为,考察拉速和过热度对方坯出结晶器坯壳厚度的影响,对比二者出结晶器横截面枝晶微观形貌.研究表明:过热度和拉速增加均能使出结晶器坯壳厚度下降,而拉速的影响更为显著.不同钢种在相同条件下出结晶器坯壳厚度下降梯度不同.过热度越低柱状晶越致密细小,利于提高连铸坯质量,拉速对柱状晶的影响相对较小.由于出结晶器坯壳安全厚度限制,过热度取15℃,低碳钢拉速不能超过2.2 m·min-1,中碳钢拉速不能超过2.5 m·min-1,据此针对不同钢种设计不同拉速可提高连铸效率.同时,模型结果显示低碳钢出结晶器时刻柱状晶更为发达. 相似文献
6.
《炼钢》2015,(4)
以某钢厂45钢大方坯为研究对象,建立了45钢凝固传热的数学模型。用双混合模型计算了45钢的热物性参数,并通过射钉试验及坯壳测温测定窄面坯壳厚度和表面温度对模型进行了验证,结果表明该数学模型能够较好的模拟45钢凝固传热过程。模拟结果表明:在现行拉速0.5 m/min,过热度为35℃工艺条件下,合适的轻压下位置在距弯月面21.8~23.1 m处;铸坯出结晶器表面温度回升幅度大,容易导致表面裂纹;稳定拉速是提高铸坯质量的关键。改进后,中心疏松等级从1.5级降到不大于1.0级,中心缩孔不大于0.5级,最大碳偏析比小于1.12,铸坯表面裂纹率由3.25%降低到0.5%;铸坯凝固末端的凝固加速是由于铸坯中心大过冷条件下钢液中等轴晶的快速生长造成的。 相似文献
7.
8.
基于涟钢板坯连铸机结构参数和冷却条件,建立了Q235B 230 mm×1 280 mm板坯连铸过程凝固传热的数值模型,研究了铸坯温度分布和坯壳厚度变化规律以及过热度和拉速对铸坯温度和凝固末端位置的影响规律。得出:随过热度和拉速的增加,铸坯中心和角部温度整体呈升高趋势,在其它参数不变的条件下,过热度每升高10℃,铸坯凝固末端和液相消失位置分别后移约0.38 m和0.31 m;拉速每升高0.1 m/min,凝固末端和液相消失位置分别后移2.06 m和1.4 m。通过数值模拟研究,掌握了铸坯温度和凝固末端位置的变化规律。 相似文献
9.
以某钢厂GCr15钢大方坯为研究对象,采用ProCAST软件建立凝固数学模型,研究了过热度、拉速和比水量对大方坯凝固过程的影响,并通过对铸坯中心固相率及液芯长度的分析,确定了最佳末端电磁搅拌位置,并优化了拉速。研究结果表明:过热度对铸坯凝固影响最小,随着过热度增加,铸坯表面温度升高,铸坯液芯长度和液相区长度均随之增加,而两相区长度则随之减小;拉速对铸坯凝固影响最大,拉速提高,铸坯表面温度、液芯长度、两相区长度、液相区长度均增大;比水量增加,铸坯表面温度降低,液芯长度减小;当比水量为0.29 L/kg时,过热度应控制在15~35℃,拉速需控制在0.46~0.49m/min,且最佳拉速为0.48 m/min。 相似文献
10.
11.
以Q460钢(/%:0.17C,0.35Si,1.5Mn,0.020P,0.020S,0.020Nb,0.075V)3 250 mm×150 mm宽板坯为研究对象,采用ANSYS软件建立凝固传热模型,研究拉坯速度、比水量、过热度等工艺参数对铸坯凝固过程的影响。模拟结果表明:拉坯速度每增大0.10 m/min,矫直段铸坯表面温度升高36.5℃,出坯温度升高50℃,坯壳厚度减薄2.4 mm,液心长度增加1.2 m;每增加1℃的过热度,矫直点铸坯上表面中心温度增加1.73℃,延长液芯长度0.11 m;因此,拉坯速度是影响铸坯质量的关键。生产应用表明,3 250 mm×150 mm板坯拉速1.20~1.25 m/min,过热度15~20℃时板坯表面矫直温度大于950℃,降低了铸坯中心疏松和偏析,表面质量显著提高。 相似文献
12.
13.
A coupled finite-element model, CON2D, has been developed to simulate temperature, stress, and shape development during the
continuous casting of steel, both in and below the mold. The model simulates a transverse section of the strand in generalized
plane strain as it moves down at the casting speed. It includes the effects of heat conduction, solidification, nonuniform
superheat dissipation due to turbulent fluid flow, mutual dependence of the heat transfer and shrinkage on the size of the
interfacial gap, the taper of the mold wall, and the thermal distortion of the mold. The stress model features an elastic-viscoplastic
creep constitutive equation that accounts for the different responses of the liquid, semisolid, delta-ferrite, and austenite
phases. Functions depending on temperature and composition are employed for properties such as thermal linear expansion. A
contact algorithm is used to prevent penetration of the shell into the mold wall due to the internal liquid pressure. An efficient
two-step algorithm is used to integrate these highly nonlinear equations. The model is validated with an analytical solution
for both temperature and stress in a solidifying slab. It is applied to simulate continuous casting of a 120 mm billet and
compares favorably with plant measurements of mold wall temperature, total heat removal, and shell thickness, including thinning
of the corner. The model is ready to investigate issues in continuous casting such as mold taper optimization, minimum shell
thickness to avoid breakouts, and maximum casting speed to avoid hot-tear crack formation due to submold bulging. 相似文献
14.
运用流体力学分析软件Fluent,对方坯连铸内外复合冷却结晶器内钢液在流场温度场耦合作用下的凝固状况进行数值模拟。并讨论了拉速对坯壳厚度的影响,经分析模拟结果表明:在浇铸温度不变的条件下,随着拉速的提高,结晶器内同一位置坯壳厚度降低,液相增加。 相似文献
15.
A simple, but comprehensive model of heat transfer and solidification of the continuous casting of steel slabs is described,
including phenomena in the mold and spray regions. The model includes a one-dimensional (1-D) transient finite-difference
calculation of heat conduction within the solidifying steel shell coupled with two-dimensional (2-D) steady-state heat conduction
within the mold wall. The model features a detailed treatment of the interfacial gap between the shell and mold, including
mass and momentum balances on the solid and liquid interfacial slag layers, and the effect of oscillation marks. The model
predicts the shell thickness, temperature distributions in the mold and shell, thickness of the resolidified and liquid powder
layers, heat-flux profiles down the wide and narrow faces, mold water temperature rise, ideal taper of the mold walls, and
other related phenomena. The important effect of the nonuniform distribution of superheat is incorporated using the results
from previous three-dimensional (3-D) turbulent fluid-flow calculations within the liquid pool. The FORTRAN program CONID
has a user-friendly interface and executes in less than 1 minute on a personal computer. Calibration of the model with several
different experimental measurements on operating slab casters is presented along with several example applications. In particular,
the model demonstrates that the increase in heat flux throughout the mold at higher casting speeds is caused by two combined
effects: a thinner interfacial gap near the top of the mold and a thinner shell toward the bottom. This modeling tool can
be applied to a wide range of practical problems in continuous casters. 相似文献
16.
薄板坯连铸结晶器内流动传热行为的研究 总被引:2,自引:0,他引:2
基于珠钢CSP薄板坯连铸机设备工艺条件和所采用扁平浸入式水口结构,结合铜板测温导出的热流密度分布进行了漏斗形结晶器内钢水流动、自由液面以及传热凝固等冶金现象的综合描述和数值分析.结晶器熔池中以两个上旋涡为主的钢水循环流动局限在漏斗形结晶器内,上旋涡流股冲击和离开熔池液面分别对液面起伏波动有所贡献,弯月面下距窄边100 mm范围内有二次涡形成.除水口下方两侧存在两个具有明显过热的高温区外,熔池中绝大部分钢水的温度在液相线附近保持恒定,铸坯表面温度分布和坯壳发育过程均反映出水口高温射流的影响,铸坯表面最高温区位于熔池液面下方靠近结晶器窄边的地方. 相似文献
17.
薄腹板异形坯更体现了近终形的特点。采用有限元数值模拟计算了薄腹板异形坯连铸温度场,分析了不同拉速、比水量对连铸过程温度、坯壳厚度和液芯长度的影响。结果表明:异形坯不同位置的温度和坯壳厚度不均匀,当异形坯腹板较薄时,腹板处凝固传热较慢,腹板处和R角处坯壳最薄弱,比翼缘边部薄约4mm;拉速每提高0.1m/s,异形坯出结晶器时的表面温度会提高约80~100℃,坯壳厚度会减薄0.8~1.2mm,液芯长度增加1.2~1.6m;比水量每提高0.05L/kg,异形坯出二冷段时的表面温度会降低约8~16℃,液芯长度缩小0.13m。 相似文献