共查询到17条相似文献,搜索用时 468 毫秒
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通过对莱钢宽厚板连铸机铸坯中间裂纹缺陷的研究分析,总结出钢水中碳、锰元素与中间裂纹产生几率的关系,认为扇形段辊缝精度和二冷强度是影响铸坯中间裂纹的关键因素,良好的辊缝精度和喷嘴状况能够有效避免铸坯中间裂纹的产生,钢水过热度和拉速等连铸工艺条件也是中间裂纹的产生因素,并根据裂纹产生的原因制定了整改措施。 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
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连铸过程铸坯已凝固坯壳因冷却降温发生热收缩变形,该变形是制定连铸机基础收缩辊缝的重要依据。以板坯连铸过程为对象,建立了三维热-力耦合有限元模型,揭示了板坯连铸过程已凝固坯壳沿厚度方向热收缩变形规律。结果表明,浇铸过程中坯壳热收缩变形不断增大,在凝固终点位置热收缩出现短时加速增大趋势,铸机末端位置坯壳宽向中心位置热收缩约8 mm;板坯宽向不同位置热收缩变形存在较明显差异,由宽向中心至铸坯角部方向,已凝固坯壳厚度方向热收缩变形呈先减小后增大趋势。随着拉速增加,相同铸流位置热收缩变形减小,拉速增加0.1 m/min,铸机末端位置的坯壳宽向中心与宽向1/8位置热收缩减小约1.2 mm。研究结果为优化铸机基础收缩辊缝,改善因不合理基础辊缝导致的铸坯内部质量问题提供了数据支撑。 相似文献
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建立二维非稳态传热模型对380 mm×490 mm大方坯凝固过程进行了模拟计算,并采用射钉试验结果验证了该模型的准确性。计算结果表明,拉速对凝固终点影响最大,过热度和比水量影响较小。拉速每增加0.01 m/min,凝固终点后移约0.5 m;过热度每增加10℃,凝固终点后移约0.3 m;比水量每减少0.02 L/kg,凝固终点后移约0.15 m。在固相率较低时进行大压下,铸坯中心质量并未改善,同时会产生2.0级的中间裂纹。通过调整拉速,在较高固相率时进行大压下,铸坯中心偏析由2.0级改善到0.5级,中心疏松和缩孔降到0.5级,并且消除了内部裂纹。 相似文献
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针对LD-氩站流程生产Q235B钢230 mm连铸板坯出现的中间裂纹,利用光学显微镜、扫描电镜和能谱仪对中间裂纹宏观和微观特征进行了系统分析。结果表明,判断扇形段接弧不良、辊缝精度差、辊子错位等是中间裂纹形成的外因;裂纹带上有粗大的晶粒,且有明显的Mn、S等元素以及复合夹杂物形态聚集是铸坯产生中间裂纹的内因。通过控制接弧精度≤±0.3mm、辊缝精度≤±0.5 mm、二冷比水量0.50 L/kg、成品[S]≤0.030%、[Mn]/[S]≥15等工艺措施,减少甚至杜绝板坯中间裂纹的发生,提高了连铸板坯的心部质量。 相似文献
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介绍了利用事故坯壳法、缺陷坯特征法及射钉试验法3种板坯铸机综合凝固系数的测定评价方法,旨在考察不同钢种综合凝固系数选取的科学性及合理性,确定不同钢种的凝固末端,为辊缝收缩设计优化、细化完善冷却制度提供科学依据;通过测定、计算与分析,分别得到的综合凝固系数为0.0240、0.0221、0.0224-0.0255m·min-0.5,其中采用事故坯壳测定法描绘出坯壳厚度与凝固时间的对应关系,得到凝固方程与理论凝固方程基本吻合;并通过优化辊缝、细化冷却制度,使铸坯低倍评级达到了C类中心偏析1.O级、中心疏松0.5级、中间裂纹0.5级。 相似文献
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Q235B钢(0. 11% ~0. 17%C)10~20 mm热轧板的生产流程为铁水预处理-50 t转炉-吹氧-(2。0 ~ 230)mm x(900 ~ 1 600)mm板坯连铸-热轧工艺。分析表明.Q235B钢热轧板表面裂纹来源于铸坯纵裂。统计分 析了成分、钢水过热度、拉速、连铸二冷水量、保护渣等对连铸坯纵裂的影响。通过控制Mn/S≥40,钢水过热度 15-35 °C,拉速1. 15 m/min,按季节调节二冷水量,釆用熔点≥1 100 °C,粘度0.20 ~0. 32 Pa .s,碱度≥1. 10的保 护渣等措施,使Q235B钢热轧板表面纵裂纹由3.51%降至W0. 96%。 相似文献
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《Baosteel Technical Research》2010,(Z1):116
Since the excessive capacity in steelmaking and continuous casting at present,and the limited development margin of CC technology and equipment in scale,the further development must be made in a profound and detailized way.This paper enumerates the items of CC technology and equipment,which need to be detailized from several aspects such as roll arrangement design,equipment design and production operation,and it points out that detailization is the future direction of CC technology and equipment.The items in roll arrangement design include eliminating periodic meniscus fluctuation by adjusting space between rolls reasonably;taking special measures to avoid dangerous regions of casting speed,in order to reduce the center porosity and centerline crack of slab;optimizing the major radius and the length of outer arc of caster before straightening point to avoid dangerous region of casting speed.The items in equipment design include choosing a suitable structure of support and guiding roll according to the concrete conditions of caster;according to bulging shape of slab,thinking more about restriction of shell to bulging force, discussing the force on rollers,optimizing split roll to support slab;safety factor should be considered together with calculation method of the bearing nominal static load.The items in aspects of continuous casting operation include the delicacy division and the function-positioning of operation modes for CC machine due to the consideration of dynamic soft reduction;monitoring and controlling system of CC machine must be further detailized to improve the stability of production operation and slab quality.In addition to the three aspects mentioned above,this article points out many other items also,such as homogenization of secondary cooling of slab,quality control of surface and internal of slab,and so on.This article emphasizes,some key technologies need to be researched also,and all these researches will never stop. 相似文献
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酒钢Q235B(0.18%C)和Q345B(0.17%C)钢CSP工艺生产的68 mm×1 600 mm铸坯的纵裂纹主要出现在炉次间的第一块铸坯,裂纹宽0.01~0.30 mm、深0.10 mm、长度≥50 mm。纵裂纹影响因素的分析结果表明,当[S]≥0.008%、钢水过热度≥40°、结晶器锥度≤4 mm时,保护渣碱度和粘度较低,以及结晶器钢板厚度≤12mm时,铸坯裂纹指数明显增加。通过控制[S]≤0.008%,钢液过热度30±5℃,结晶器液面波动±3 mm,Q235B钢裂纹发生率由2%降至0.36%,Q345B钢由5%降至0.98%。 相似文献
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The present investigation was undertaken in context with the development of the single‐belt strip casting process. In this new process the casting is directly connected to hot rolling which must be carried out at lower speed than in conventional hot rolling to match the casting rate. We have used an integrated thermal/mechanical finite element model to theoretically study the effect of rolling speed on rolling parameters. Since the model is general and the question of “slow hot rolling” is of general interest, the computations were carried out for a wide range of volumetric flow rate extending from that in thin slab casting to that in conventional finishing rolling. The results are given on the influence of rolling speed on roll force, torque, power, temperature change of stock and roll, and roll life. The most important effect of slow hot rolling seems to be the increased heat up of the rolls. This causes an increase of plastic strain in the near surface region of the rolls that will intensify the formation of fatigue cracks. 相似文献