板坯连铸结晶器铜板冷却水槽结构优化

针对板坯连铸结晶器铜板冷却水槽的结构优化,将三维传热模型应用于结晶器铜板导热过程,并采用有限元方法进行了模拟,计算并比较了水槽结构优化前后结晶器宽面铜板热面温度分布情况.结果表明:水槽结构优化后铜板螺栓处温度较优化前降低6℃,弯月面处温度降低10℃;优化前和优化后铜板在螺栓处和弯月面处的温度波动幅度分别为3、1. 5℃和8、2℃,水槽结构优化后铜板传热能力和冷却均匀性有明显提高.     

冷却结构对连铸结晶器铜板热变形的影响

建立了板坯连铸结晶器三维有限元热弹塑性结构模型,计算了铜板变形及结晶器冷却结构对其影响规律.冷却结构和热力载荷决定了铜板热面变形行为,铜板变形量取决于冷却结构几何参数,并在铜镍分界处有较小变形突变;宽面热面中心线最大变形出现在弯月面下100mm处,窄面最大变形出现在弯月面和冷却水槽末端,且铜镍分界两侧变形曲线有明显的曲率波动;铜板加厚5 mm,最大中心线变形可增加0.05 mm,镍层对中心线变形影响不明显,1 mm的厚度变化仅在窄面引起最大0.01 mm的下降,冷却水槽对中心线变形影响也较小,水槽加深2 mm,最大中心线变形减少0.02 mm.      

非均匀冷却型结晶器铜板的传热特性

针对唐钢新型的FTSC非均匀冷却型结晶器,根据连铸结晶器的铜板实测温度、结晶器水量和进出水温差,建立了结晶器热流一维修正计算模型及其分布曲面,分析在生产SS400钢种时不同条件下的结晶器铜板热流分布特点,结果表明,相同条件下热流分布趋势和热面温度分布趋势相似,横向上波动剧烈,在距离铜板中心线400mm处的热流最高,距离弯月面越近波动越剧烈,在结晶器下部,中心部位的热流较低,并且平直段热流比漏斗区域的热流低;沿着结晶器高度方向,热流和热面温度变化梯度较小,在结晶器中部会有一个热流以及热面温度回升趋势;在整个铜板宽面上,热流较高,热面温度较低,这对提高结晶器使用寿命具有积极意义。     

板坯连铸结晶器铜板温度场的数值仿真

针对 14 0 0mm× 170mm板坯连铸机结晶器铜板的结构优化改造 ,基于控制容积的有限差分方法对改造前后两种铜板结构参数和深入式水口结构参数条件下结晶器铜板的三维稳态温度场进行了数值仿真研究。由仿真得出的结果表明 ,结晶器宽面铜板经优化改造后 (螺栓间距由 16 0mm改成 135mm、冷却水槽由 6 3条改为 5 5条 )传热效果明显增强 :在拉速为 1.4m min时弯月面附近区域改造后结晶器内弧和外弧宽面热面铜板最高温度值分别比改造前结晶器降低了 15℃和 16℃。     

基于热流密度分布模型的连铸倒角结晶器温度分布研究

基于热流密度分布模型,建立了全弧形板坯连铸机倒角结晶器窄面冷却水流动和铜板传热耦合的数学模型。采用多元回归的方法拟合得到描述连铸结晶器热流密度对结晶器高度的函数表达式。铜板表面沿拉坯方向的热流密度呈非线性分布,弯月面附近的热流密度先急剧增加然后迅速减小,在距离弯月面0.1 m处的热流密度达到最大值。模型计算结果表明,在结晶器距上口150～200 mm的铜板表面温度最高达到608～678 K,低于723 K的铬锆铜再结晶软化温度;尽管该区域铜板水缝的最高表面温度近420 K,但不影响整体传热。计算的铜板温度与热电偶测量值相吻合。     

高拉速下板坯连铸结晶器铜板传热行为研究

基于首钢京唐钢铁联合有限责任公司高拉速连铸生产低碳钢过程,采用ANSYS软件建立结晶器铜板传热的三维有限元模型,并结合现场实测冷却水和铜板温度数据,研究了高拉速下结晶器铜板的温度场。计算结果表明,有无冷却背板结晶器铜板温度分布差别不大;不同拉速时结晶器底部均出现一定的回温现象,且随着拉速的升高,回温幅度逐渐增大;拉速提高铜板热面温度升高,但幅度逐渐减小;拉速为2.3 m/min时,铜板热面中心最高温度为328.0℃,出现在弯月面以下10 mm左右的位置;镀层会导致铜板热面温度的升高,且升高幅度与镀层厚度正相关;增大水量在一定范围内能够降低铜板温度。     

异型坯连铸结晶器传热行为的数值模拟研究

利用ABAQUS有限元软件建立异型坯连铸结晶器铜板的三维有限元模型,并通过ABAQUS用户子程序施加传热边界条件,对现有的异型坯结晶器铜板温度场进行数值模拟研究,重点分析铜板热面温度的分布规律,并对其进行优化,得到合理的温度场分布.给出了水槽和水孔中冷却水流速、铜板厚度以及拉坯速度等工艺参数对结晶器铜板温度场的影响规律...     

倒角结晶器铜板实际温度场数值仿真

 以首钢京唐实际生产过程中倒角结晶器的铜板尺寸、水道布置、铜板实测温度、宽窄面水量和进出水温差为基础,运用商业软件ANSYS模拟了实际生产过程中倒角结晶器铜板温度分布。计算结果表明：距弯月面0～300 mm,倒角结晶器窄面横向温度分布呈W型,和直角结晶器倒U型温度分布有很大差别;距弯月面300～800 mm,角部温度迅速降低,温度分布呈倒U型,和直角结晶器温度分布基本一致;此外,倒角结晶器倒角面的温度梯度较大,倒角面上坯壳与铜板之间的换热热流波动较大,这说明倒角坯的缺陷主要出现在倒角面,这与实际是相符合的。     

提高亚包晶钢板坯拉速对结晶器传热的影响

通过对提高亚包晶钢AQ钢种230 mm×1200 mm板坯拉速试验过程中结晶器冷却水参数、铜板测温等数据进行适时记录,并与数学模型及ANSYS商业软件相结合,研究了提高拉速对结晶器平均热流、局部热流、铜板温度场以及坯壳厚度的影响。结果表明,拉速由1.3m/min提高到1.5m/min时,平均热流增加0.1 MW/m²左右,宽边弯月面区域局部热流增加0.13 MW/m²,但均在合理范围内,这与采用高碱度高结晶温度的试验保护渣有关;结晶器窄/宽面平均热流比超过0.9,应适当减少结晶器锥度;宽面坯壳厚度平均减薄4 mm左右,应严格控制结晶器传热强度,以保证连铸工艺稳定和铸坯质量。     

薄板坯连铸结晶器热流分布研究

通过结晶器温度检测软件在线采集了武汉钢铁(集团)公司CSP结晶器铜板的温度,根据热电偶实测温度及连铸机冷却参数,计算了浇铸不同断面SPHC钢时不同拉速的热流值,并建立了结晶器热流的二维分布模型。结果表明,结晶器受水口射流影响,热流与温度在宽面横向分布很不均匀,表现出明显的双峰结构。相同工况条件下在铜板宽度方向上温度和热流密度分布具有相似性,距离弯月面越近,热流密度和温度的波动越大,弯月面处热流密度最大值达到4.6 MW/m2。     

连铸管式结晶器变形的数值仿真与优化

为了减小管式结晶器铜板变形,提高铸坯质量,建立钢液-铜管-冷却水的三维流动传热模型以及铜管应变模型,研究管式结晶器传热和形变特征,提出铜管优化方案.研究结果表明,铜管热面最高温度为500 K,最低温度为320 K,铜管角部60 mm区域的冷却水温度最低;铜管角部的变形量最大,角部和窄面中心向水缝侧变形,铜管宽面中心向钢...     

Analysis of Thermal Behavior for Beam Blank Continuous Casting Mold

Finite element models of steady heat conduction for cross section of beam blank mold were developed by using ABAQUS software.The effect of mold grinding thickness,cooling water velocity,diameter of restrictor rods and water channel design on hot face temperature was analyzed in detail.Attention was focused on the peak temperature and temperature uniformity along hot face.The results showed that the peak temperature of existing mold,about 337.2 ℃,is located in the fillet,and two valleys of hot face temperature are found in flange corner and junction of wide face and narrow face,respectively.Decreasing mold thickness,increasing cooling water velocity and increasing diameter of restrictor rods can all reduce peak temperature and improve temperature uniformity along hot race at the expense of lower overall temperature.Redesigning the water channel can decrease peak temperature and thermal gradient of mold without lowering overall temperature of hot face.In particular,the small hole design can improve temperature uniformity across hot face and obtain the best advantage.     

Mold behavior and its influence on quality in the continuous casting of steel slabs: Part II. Mold heat transfer,mold flux behavior,formation of oscillation marks,longitudinal off-corner depressions,and subsurface cracks

Axial heat-flux profiles have been determined quantitatively from temperature measurements conducted on a slab mold under routine operating conditions. As in earlier studies, the heat flux was observed to have a maximum value at the meniscus and to decline with increasing distance down the mold. The mold heat flux increased with increasing casting speed and was greater with a mold powder having lower viscosity and melting point being applied as lubricant. The heat extraction was largest while casting 0.29 pet carbon steel and least for a 0.09 pet carbon grade; reducing the depth of the submerged entry nozzle increased the heat flux slightly in the upper region of the mold. Most significant was the higher heat flux observed at the meniscus of the outside-radius face, attributable to the locally greater copper plate thickness compared to that of the opposite broad face. All of the measurements can be explained straightforwardly by heat flow in the vicinity of the meniscus and the resulting behavior of the so-called slag rim adjacent to the mold wall. It is postulated that the difference in copper plate thickness between the two broad faces at the meniscus causes the slag rim to be smaller on the outside-radius face which gives rise to shallower oscillation marks, as observed, higher heat transfer, and a slightly thicker solid shell. The dissimilar behavior has implications for quality because the inside-radius shell, experiencing reduced heat extraction, cools and shrinks less than the outside-radius shell. Thus, for a given end-plate taper, the narrow face of the slab adjacent to the inside radius can push against the end plate, accelerating copper wear, and, owing to squeezing of the broad face, cause an off-corner depression and subsurface crack toward the mold exit. If this is correct, maintenance of the same copper plate thickness at the meniscus is fundamental to preventing such an occurrence. Moreover, adjustment of the heat extraction at the meniscus should be achievable by changing copper plate thickness, mold coating thickness/conductivity, cooling water velocity, cooling channel configuration, and mold flux composition for a given steel grade. Formerly Graduate Student, Centre for Metallurgical Process Engineering, The University of British Columbia,     

The Thermal Distortion of a Funnel Mold

This article investigates the thermal distortion of a funnel mold for continuous casting of thin slabs and explores the implications on taper and solidification of the steel shell. The three-dimensional mold temperatures are calculated using shell-mold heat flux and cooling water profiles that were calibrated with plant measurements. The thermal stresses and distorted shape of the mold are calculated with a detailed finite-element model of a symmetric fourth of the entire mold and waterbox assembly, and they are validated with plant thermocouple data and measurements of the wear of the narrow-face copper mold plates. The narrow-face mold distorts into the typical parabolic arc, and the wide face distorts into a ??W?? shape owing to the large variation in bolt stiffnesses. The thermal expansion of the wide face works against the applied narrow-face taper and funnel effects, so the effect of thermal distortion must be considered to accurately predict the ideal mold taper.     

宽厚板坯连铸结晶器流场、温度场及应力场的耦合数值模拟

利用Pro CAST软件对2400 mm×400 mm宽厚板坯结晶器建立三维动态模型,采用移动边界法实现结晶器内流场、温度场及应力场的耦合模拟.结果表明:考虑凝固坯壳的影响,下回流区位置向铸坯中心靠拢,真实反映了钢液在连铸结晶器内的流动情况.自由液面的钢液从窄面流向水口,速度先增大后减小,距水口约0.7 m处,出现最大表面流速,约为0.21 m·s-1.结晶器出口坯壳窄面中心厚度最小且由中心向两侧逐渐增大,最小厚度约为10.4 mm;受流股冲击影响较弱的宽面坯壳与窄面相比生长更均匀,宽面偏角部和中心的坯壳厚度分别为18.9 mm和27.6 mm.铸坯坯壳应力变化趋势与温度基本保持一致,表明初凝坯壳应力主要是热应力.结晶器内铸坯宽窄面上的等效应力均沿着结晶器高度下降方向呈增大趋势,铸坯角部、宽面中心及窄面中心位置的最大应力各约为200、100和25 MPa.      

连铸坯实测反问题热弹黏塑性建模与分析

为了研究连铸板坯的传热和力学特征,通过建立考虑蠕变的铸坯热弹黏塑性全尺寸有限元数值模型,以实测温度和传热反问题获得的热流为依据,计算和探讨了结晶器内铸坯的传热、应力和应变行为。结果表明,弯月面下100 ~ 200 mm铸坯表面承受拉应力,宽面距角部40 ~ 90 mm的偏角部区域温度较高,坯壳厚度也较薄,距角部约400 mm处温度相对较低,收缩量及应力应变较大。窄面近角部区域的应力和应变总体上低于宽面,距角部越近,窄面铸坯表面的应变越高。偏角部区域坯壳厚度、应力、应变的非均匀性及存在的过大差异,是探讨近角部裂纹成因需要考虑的重要因素。     

利用冷却板修复铜冷却壁技术分析

铜冷却壁水管损坏时热面温度急剧升高,加剧冷却壁烧损。此时往往采用冷却柱恢复冷却能力,冷却柱为“点”冷却,冷却面积小且不易造衬。而利用冷却板代替损坏部位的冷却壁,容易形成平滑操作炉型,有利于高炉顺行。建立冷却板棋盘式布局模型,从冷却板间距、尺寸、冷却水速等方面分析炉壳表面以及冷却壁冷、热面的冷却中心温度,结果表明当煤气温度1500℃时,冷却间距从200mm增大到600mm,炉壳外表面冷却中心温度增高约230℃;冷却板水速从1m/s升至3m/s,炉壳外表面冷却中心的温度降低50℃左右;并与冷却柱比较发现,冷却板冷却效果明显强于冷却柱。     

铜板厚度对板坯结晶器热力行为的影响

基于某钢厂的铸机条件,建立了三维热弹塑性有限元模型,得到了不同厚度铜板的温度、变形量和等效应力应变的分布状态,指导了河北普阳钢铁有限公司结晶器的设计。结果表明：铜板越厚,热面温度越高,等效应力越小,变形量越大。铜板厚度每增加5mm,热面最高温度将相应增加30℃左右;热面最大等效应力将减dx7．5MPa2左右;热面最大变形量将相应增加0．05mm左右;较薄的铜板可减少浇铸过程中铜板的热变形。