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连铸坯可能出现表面裂纹,其在轧制过程中的演变行为严重影响着轧制产品的质量。本文采用热力耦合有限元方法对轧制过程轧件表面裂纹演变行为进行了分析。获取了轧制过程中轧制变形区内轧件表面裂纹形状变化规律、裂纹附近区域应力场和温度场分布场分布情况。计算结果表明在轧制入口区域,裂纹逐渐闭合,然而,在轧制出口区域,裂纹又重新扩展开,裂纹尖端处呈现拉应力状态。同时,发现变形区内裂纹尖端发生温度成双峰变化规律。 相似文献
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YU Hai-liang LIU Xiang-hua LI Chang-sheng Y. Kusaba 《钢铁研究学报(英文版)》2006,13(6):31-37
The behavior of transversal cracks on the surface of the slab corner during vertical and horizontal (V-H) rolling process with flat vertical roll and groove vertical roll was simulated by explicit dynamic finite element method. The closure and growth of crack and the contact pressure on surfaces of the crack in contacting zone between slab and roll during rolling process were analyzed. The results showed that during vertical rolling process, when the groove vertical roll is used, the maximum contact pressure on surfaces of the crack is 115 MPa, and the closure of crack is stable when the flat vertical roll is used, the maximum contact pressure on surfaces of the crack is 70 MPa, and it fluctuates greatly. During horizontal rolling process, when groove vertical roll is used, the contact pressure becomes zero which may accelerate the growth of crack when flat vertical roll is used, there is still contact pressure. The cal culated results are in good agreement with the results of test. 相似文献
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The behaviour of longitudinal cracks on slab surfaces in multi‐pass vertical‐horizontal rolling processes was simulated by the finite element method (FEM). The influence of friction coefficients and fillet radii of grooved edge rolls on the closure and growth of cracks were analysed in regard to crack shape and crack length elongation ratio. The results indicate that the crack width increases both with increasing friction coefficient and with increasing fillet radii of the grooved edger rolls; the crack length increases as the fillet radii increase in V1 and H1 passes, and decreases as the fillet radii increase in V2 ~ H3 rolling. Moreover, the cracks become longer under a higher friction coefficient. Experiments of the behaviour of longitudinal cracks on slab surfaces in multi‐pass V‐H rolling processes were investigated taking lead as model material for the hot rolling of steel. The calculated results showed similar deformation variations compared to the experimental ones. 相似文献
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连铸坯表面裂纹的控制 总被引:25,自引:0,他引:25
生产无缺陷的连铸坯是连铸坯热送、热装的前提条件.铸坯表面裂纹可能导致最终轧制产品出现缺陷.简要评述了影响连铸坯表面纵裂纹、横裂纹和星形裂纹形成的原因,及防止表面裂纹产生的技术措施. 相似文献
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热带粗轧机组调宽时材料的变形行为 总被引:1,自引:0,他引:1
为实现连铸与热带轧制宽度的衔接,热带粗轧机组中广泛采用宽度方向大侧压的方法。本文简要地论述了采用平辊立轧-平轧方式调宽过程中轧件的主要变形特点,并指出了我国今后在现有热带热轧机上采用粗轧调宽技术的途径。 相似文献
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微合金化钢连铸坯角部横裂纹形成机制 总被引:1,自引:0,他引:1
为研究微合金钢连铸坯角部横裂纹缺陷形成机制问题,从理论上研究了连铸过程第二相粒子的析出行为,并在板坯连铸生产中进行"卧坯"试验。研究结果表明:X65管线钢中碳氮化钛、碳氮化铌、氮化铝的开始析出温度分别为1 508、1 123、1 165℃,析出峰值温度分别为1 360、870和840℃;"卧坯"试验发现结晶器内及垂直段无裂纹,在距弯月面3 270mm处,即对应于弯曲开始后710mm开始出现多处外弧横裂纹,而弧形段内无内弧裂纹,在弯曲段铸坯角部温度处于钢的第Ⅲ脆性区,同时外弧受拉应力,这是造成外弧角横裂产生的主要原因。 相似文献
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To improve the current grinding procedure of the back-up roll of CVC hot rolling mills so that the back-up roll service life can be extended, the crack initiation and propagation behavior of medium carbon bainitic back-up roll steel was investigated, a kind of asperity-scale, surface originated vertical short cracks occurred at 5 × 10^2 -1 × 10^4 cycles. Theoretical analysis indicated that the maximum tensile stress occurring at the back edge of the contact of asperities keeps at above 1 347. 97 MPa, and ratcheting and cyclic plastic deformation take place at such sites within 1 × 10^4 cycles. The early initiation of the vertical short cracks is caused by the asperity contact. According to the crack initiation mechanism, short crack behavior and preventive grinding strategy, steel consumption can be reduced considerably by decreasing the surface roughness and removing the asperity influenced surface thin layer at about 70%-80% of the surface distress life. 相似文献
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针对天钢4号板坯连铸机生产铸坯的纵裂纹缺陷,利用低倍分析、扫描电子显微镜以及测量技术,对铸坯试样和使用的设备部件进行了检测分析,揭示了纵裂纹产生的原因是铸机结晶器的锥度不稳定,导致结晶器窄边对铸坯凝固壳的支撑力降低,导致铸坯裂纹。在此基础上采取了有效措施,避免了天钢4号板坯连铸机生产的铸坯的纵裂纹缺陷。 相似文献
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本钢薄板坯连铸连轧生产线在调试生产阶段,精轧机乃多次出现轧裂卡钢停产事故。对轧裂钢板试样进行组织、夹杂物分析,结果表明,钢板严重的组织不均匀性是导致Q235热轧钢板轧裂的主要原因。采取降低连铸时钢水的过热度、提高铸坯出加热炉温度及增大粗轧阶段的压下量等工艺措施后,没有出现过F3轧裂卡钢事故。 相似文献
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结合设备特点、产品宽度控制手段以及宽度控制理论,详细分析了2250mm热连轧生产线的成品宽度尺寸波动的影响因素。通过对定宽机的短行程控制消除头尾宽展的异常变化,以板坯宽度尺寸的测量消除来料宽度尺寸波动的影响,以精轧张力控制以及立辊的自由张力控制系统的优化消除头尾拉窄现象,有效地解决了宽度控制中存在的问题。 相似文献
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Sarmishtha Palit Sagar G. V. S. Murthy Tarun Kumar Das Amit Prakash Uday Shankar Goel T. Venugopalan 《国际钢铁研究》2013,84(2):163-168
Over the last few years, the use of work rolls for hot rolling of flat steel has been changed from clear chill rolls to indefinite chill, then high chrome steel and now high speed tool steel (HSS). HSS rolls are highly crack‐sensitive because of its high surface hardness. The crack propagation develops within the working surface of the roll, gradually increases in depth and width followed by a large “cats‐tongue” band type spalls of the overlying barrel surface and that leads to abnormal roll failure. This paper presents the development of surface wave based ultrasonic technique to optimize the grinding procedure for having crack free roll surface. 相似文献