共查询到19条相似文献,搜索用时 984 毫秒
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确定轴承钢在连铸坯凝固末端的位置,对于轴承钢轻压下工艺的合理制定、改善铸坯的中心疏松及中心偏析等缺陷具有至关重要的意义。首先,采用二维非稳态传热方程,结合本钢350mm×470mm矩形坯铸机自身特点,建立了矩形坯凝固模型。其次,通过射钉试验,取片做硫印,来标定生产状态下不同位置的坯壳厚度。最后,对铸坯的表面温度进行了实际测定。研究结果表明,射钉硫印测量的坯壳厚度、实测的铸坯表面温度都与凝固模型的计算结果相近,实际生产过程中,完全可以采用该模型来理论计算铸坯凝固末端,为轻压下工艺提供理论依据。 相似文献
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以国内某钢厂断面为150mm×150mm的82B钢连铸小方坯为研究对象,建立连铸小方坯凝固传热模型,采用铸坯表面温度测量方法验证模型可靠性。依据铸坯凝固率fs=0.7~0.8为末端电磁搅拌合理安装位置,根据模拟结果得出,在实际生产过程中过热度波动范围为20~40℃时,末端电磁搅拌最佳安装位置为距弯月面6.59~6.79m位置处。结合现场实际情况确定在距弯月面6.73m处安装末端电磁搅拌,并进行工业实验分析了末端电磁搅拌的应用效果。结果表明:施加末端电磁搅拌后,铸坯与盘条质量均有所改善。连铸坯平均碳偏析指数由1.05降至0.99,最大碳偏析指数由1.12降至1.05,中心等轴晶率由36%升高到39%;盘条中心偏析评级由2.5级下降到1.5级,网状渗碳体级别由4级下降到1级。 相似文献
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凝固末端电磁搅拌参数确定及其对中心偏析的影响 总被引:2,自引:0,他引:2
结合南京钢铁股份有限公司电炉厂方坯连铸机的生产实际,用数学模型初步计算凝固末端的坯壳厚度,利用射钉结果对数学模型进行修正,通过一定拉速下、一定钢种的温度场的计算,找出液芯为35~55 mm的位置,确定将末端电磁搅拌器安装在距弯月面8 m处.并利用特斯拉计现场测试二冷末端电磁搅拌器的磁感应强度,确定电流为550 A,频率为13 Hz时的参数为最佳搅拌参数.同时对一定条件下的铸坯进行了化学成分化验,结果表明经过末端电磁搅拌的连铸坯试样中心碳和硫的偏析程度与未经过末端电磁搅拌的试样相比有不同程度的减轻,冶金效果比较理想. 相似文献
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对80号钢小方坯内部质量差的问题进行分析,发现末端电磁搅拌(FEMS)磁感应强度低,难以满足末搅冶金的效果。为弥补FEMS强度的不足,拉速由2.6提高到2.7 m/min,二冷比水量降为原工艺的90%。凝固传热模型计算表明,FEMS位置的液芯厚度由原工艺的47.6提高到52.8 mm。试验结果表明,铸坯酸洗表面未出现缺陷,低倍质量明显改善,碳偏析指数范围由原工艺的0.96~1.09优化至0.97~1.02,达到改善铸坯内部质量的目的。 相似文献
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为了控制梅钢1 650板坯连铸包晶钢过程铸坯内裂纹发生,基于梅钢1 650板坯连铸机生产实际,建立了1 560mm×230mm断面包晶钢铸坯凝固过程三维热/力耦合有限元模型,揭示了铸坯凝固过程各冷却区内的温度场分布规律和铸坯压下过程应力与变形行为演变规律。结果表明,铸坯在结晶器及零段内冷却强度大,沿拉坯及其垂直方向的温度分布梯度大;在实施铸坯凝固末端压下过程中,铸坯宽面中心与宽向1/4处的表面变形及应力变化较为同步,且靠近铸坯内弧侧凝固前沿的塑性应变最大,铸坯应力最大值集中在角部区域;目前梅钢包晶钢连铸压下区间设置不当,易引发铸坯产生内部裂纹。 相似文献
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用二维切片跟踪铸坯凝固传热的方法建立了X80管线钢(/%:0.04C,1.85Mn,0.25Si,0.006P,0.003S,0.30Ni,0.21Mo,0.06Nb,0.02V)238 mm×1650 mm板坯连铸过程中垂直拉坯方向传热的数学模型,通过ANSYS对X80管线钢连铸过程中温度场及坯壳厚度的渐变进行计算,得出拉速1.2mm/min时,出结晶器坯壳厚为18.14 mm,铸坯液芯长22.58 m。凝固壳厚度计算值射钉测试结果的相对误差≤2.5%,凝固末端位置的相对误差为0.68%。分析了过热度(25~55℃),拉速(1.2~1.3m/min)和二冷水量(79.2~96.8 m3/h)对切片各点温度和凝固末端位置的影响。结果表明,增大拉速、减小二冷配水量,连铸坯表面温降变慢,凝固末端位置距离结晶器液面越远,凝固时间变长;该X80管线钢板坯连铸最佳工艺参数为钢水过热度35℃,拉速1.2 m/min和二冷配水量88m3/h。 相似文献
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以钢厂断面尺寸为Φ800 mm圆坯Q355NE为研究对象,建立大圆坯传热模型,在不采用结晶器电磁搅拌的条件下,研究拉速和过热度对凝固过程的影响规律。结果表明:拉速对坯壳厚度、凝固终点位置和中心固相率的影响高于过热度,拉速每增加0.02 m·min-1,凝固终点后移2.6 m左右;过热度升高10℃,凝固终点后移0.21 m左右。实际生产中,二冷比水量0.18 L·kg-1、过热度25℃、拉速0.14 m·min-1时,出结晶器坯壳厚度超过43 mm,末端电磁搅拌充分发挥作用,铸坯中心疏松和中心缩孔较结晶器电磁搅拌(300 A/1.5 Hz)、二冷比水量0.18 L·kg-1、过热度25℃、拉速0.16 m·min-1工艺有所改善。 相似文献
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LIU Shao- wei HAN Yan- shen GUAN Min ZHANG Bing- xiang ZENG Fan- zheng LIU Qing 《钢铁研究学报》2018,30(9):716-722
A solidification and heat transfer model of continuous casting billet was established and verified by surface temperature measurement for 82B high carbon steel with the section size of 150mm ?? 150mm in a domestic steel plant. Taking solidification ratio fs=0. 7-0. 8 of the billet as the reasonable installation position of final electromagnetic stirring (FEMS), the most suitable position of FEMS was determined at 6. 59-6. 79m distance from meniscus with the variation of superheat from 20?? to 40?? according to numerical results. Combined with the actual situation in the production site, the final- electromagnetic stirrer was installed at the position of 6. 73m distance from meniscus and industrial trials were carried out to verify the effect of FEMS. The results indicate that the quality of billet and wire rod is improved after the application of FEMS. For billet, the average carbon segregation index decreases from 1. 05 to 0. 99, the maximum carbon segregation index decreases from 1. 12 to 1. 05, and the central equiaxed crystal ratio increases from 36% to 39%. For wire rod, the central segregation grade decreases from 2. 5 to 1. 5 and the network cementite grade decreases from 4 to 1. 相似文献
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以某钢厂圆坯连铸机为研究对象,建立了连铸坯凝固传热模型。在不同拉速下对280 mm断面圆坯二次冷却过程进行仿真优化,确定了16MnNb钢合适的二冷制度。根据仿真结果,在最小工作拉速(0.9 m/min)下,矫直点处铸坯内弧表面中心温度为947 ℃,有效避开了铸坯的二次低延性区。在最大工作拉速(1.2 m/min)下,铸坯出结晶器时,其凝固坯壳厚度为19 mm,二冷初期产生漏钢等质量问题的可能性较小。不同拉速下,横断面温度场分布均匀。经低倍检测发现,铸坯表面及内部质量良好,无裂纹、疏松、缩孔等质量缺陷。 相似文献
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《钢铁冶炼》2013,40(5):359-375
AbstractA finite element thermal stress model to compute the thermomechanical state of the solidifying shell during continuous casting of steel in a square billet casting mould has been applied to investigate longitudinal cracks. A two-dimensional thermoelastoviscoplastic analysis was carried out within a horizontal slice of the solidifying strand which moves vertically within and just below the mould. The model calculates the temperature distributions, the stresses, the strains in the solidifying shell, and the intermittent air gap between the casting mould and the solidifying strand. Model predictions were verified with both an analytical solution and a plant trial. The model was then applied to study the effect of mould corner radius on longitudinal crack formation for casting in a typical 0·75%/m tapered mould with both oil and mould powder lubrication. With this inadequate linear taper, a gap forms between the shell and the mould in the corner region. As the corner radius of the billet increases from 4 to 15 mm, this gap spreads further around the corner towards the centre of the strand and becomes larger. This leads to more temperature non-uniformity around the billet perimeter as solidification proceeds. Longitudinal corner surface cracks are predicted to form only in the large corner radius billet, owing to tension in the hotter and thinner shell along the corner during solidification in the mould. Off corner internal cracks form more readily in the small corner radius billet. They are caused by bulging below the mould, which bends the thin, weak shell around the corner, creating tensile strain on the solidification front where these longitudinal cracks are ultimately observed. 相似文献
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The continuous casting process is used for solidifying molten steel into semi-finished steel.The technology of secondary cooling is extremely important for output of the casting machine and billet quality.A dynamic water model was introduced,including solidification model in the secondary cooling,feedforward control strategy based on continuous temperature measurement in tundish,and feedback control strategy based on surface temperature measurement.The mathematical model of solidification process was developed according to the principle of solidification,and the solidification model was validated by measuring billet shell thickness through shooting nail and sulfur print.Primary water distribution was calculated by the solidification model according to procedure parameters,and it was adjusted by the other two control strategies online.The model was applied on some caster and billet quality was obviously improved,indicating that the dynamic water model is better than conventional ones. 相似文献
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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
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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