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统计了唐钢第二钢轧厂方坯连铸机2010年漏钢情况,分析了夹渣漏钢、粘结漏钢和角部裂纹漏钢的特点及机理,找出了漏钢产生的主要原因与保护渣的性能、结晶器的精度、钢水过热度、拉速、浸入式水口的对中、操作等因素有关,采取相应的改进措施后,铸机的漏钢率有了明显降低。 相似文献
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利用光学显微镜、扫描电镜等方法分析了矩形连铸坯表面角部纵裂纹形貌及其缝内夹杂物成分,并从钢水过热度、保护渣性能、液面波动、结晶器进水温度、结晶器与扇形段对中等方面对裂纹成因进行了研究。结果表明,在裂纹缝隙间填充着含Na、Ca、Si、Al、O元素的夹杂物,其组成与保护渣的化学组成基本相同,说明裂纹主要产生于结晶器内,其主要产生原因是开浇前结晶器进水温度偏低及结晶器与扇形段弧度不对中。通过提高连铸开浇水温至20℃以上、调整结晶器与扇形段对中精度、定期更换过度磨损的结晶器等措施,矩形连铸坯表面角部纵裂缺陷发生率降低了98%,板坯质量得到明显改善。 相似文献
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结合天铁炼钢厂0#连铸机的实际生产情况,从多方面分析了表面纵裂的产生因素,发现表面纵裂与钢水成分、拉速、钢水过热度、结晶器冷却强度、保护渣等因素密切相关。通过采取对转炉钢水控制终点化学成分、稳定连铸拉速、优化结晶器冷却制度、改进保护渣性能等相应措施,使表面纵裂得到有效控制。 相似文献
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小方坯角部纵裂漏钢的根本原因就是因为在铸坯角部产生剪切应力所造成的,而铸坯厚度不均匀程度越大角部剪切应力就越大,影响铸坯坯壳厚度生长不均匀的因素包括:结晶器尺寸、结晶器振动、二冷冷却和工艺因素等。我厂根据不同的原因进行详细的分析并制定出了相应的措施,从根本上解决了小方坯角部纵裂漏钢的问题。 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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《钢铁冶炼》2013,40(3):166-172
AbstractAn optimum casting model was developed to simulate the effect of mould flux on bloom heat transfer and strain behaviour based on a 3D MiLE method, and the influence of casting speed and superheat on bloom heat transfer and lubrication were also investigated. The simulation results showed that solidified shell thickness growth conforms to a Square Root Law, and that the model predicted results are basically in agreement with previous data in the literature, and provide confidence in model. The bloom temperature distribution range in the corner area is smaller than that in the mid-face, and the corner regions form a high cracking risk zone. The hot tearing indicator and effective stress in the corner area are significantly greater than that in the mid-face, so the corner area is the dangerous zone of cracking; The mould flux lubrication in the bloom mid-face is better than for the bloom corner region, due to a higher shell temperature and a fluid slag; The increasing of casting speed can delay air gap formation of the bloom corner area, improving the lubrication conditions, but when the casting speed is changed, it is also necessary for the mould flux viscosity and crystallization temperature be changed also. Increasing the superheat has little influence on the completely solidified distance of liquid flux in the bloom corner area. 相似文献
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板坯连铸倒角结晶器的开发与应用 总被引:2,自引:0,他引:2
为减少连铸板坯角部横裂纹,在分析连铸坯角部横裂纹形成机制的基础上,提出了通过倒角结晶器减少角部横裂纹,以改变连铸板坯角部的二维传热,提高矫直时连铸坯的角部温度。数值模拟计算的结果表明,相对于直角连铸坯,倒角连铸坯在矫直区连铸坯角部温度明显提高,消除了角部Z向应力和应变集中。工业生产数据表明,采用倒角结晶器后,矫直区连铸坯角部温度从810~855℃提高到901~932℃,有效避开了钢的高温脆性区,连铸坯角部横裂纹发生率从10.6%稳定控制到1.6%以下,显著减少了连铸坯角部横裂纹。目前倒角结晶器稳定应用于首秦,所生产钢种涵盖了普碳钢、低合金钢、低碳钢和中碳含铌钢等。 相似文献
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通过对含铌钢HRB400Nb 180 mm×180 mm连铸坯产生的角部裂纹进行研究分析,结果表明,由于连铸冷却工艺、钢水氮含量和结晶器保护渣工艺控制不当易导致含铌钢铸坯角部沿晶开裂。通过工艺改进钢液氮含量由原(67~98)×10-6降至(40~55)×10-6,结晶器角部圆弧半径由8 mm调整为12 mm,结晶器冷却水量由150m3/h降至120m3/h,二冷比水量由1.35 L/kg降至1.1L/kg,二冷分配比由26:48:17:9调整为36:34:19:11,保护渣碱度由0.65调整为0.82、粘度由1.3 pa·s调整为0.69 pa·s、熔点由1260℃调整为1150℃等,有效解决了铸坯表面角部裂纹缺陷,保证了轧材的产品质量。 相似文献