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方坯高效连铸技术的进展 总被引:3,自引:0,他引:3
1.前言 纵观世界连铸技术发展过程,在连铸比不断上升的同时,连铸一直在向提高生产效率的方向迈进。进入九十年代,铸机生产能力大幅度提高,国际上小方坯连铸单流年产量平均达13万t,1995年初日本小方坯连铸机的拉速就普遍在3~3.5m/min,目前国外铸机有的 相似文献
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广钢转炉分厂现有3座8t氧气顶吹转炉,配吹氩喂丝机和一台R6m三机三流德马克型的小方坯连铸机问号连铸机),以及浇铸267mm×267mm钢锭设施。为实现全连铸,广钢转炉分厂新上了2号连铸机(罗可普改进型)。1工艺参数2#连铸机的其主要工艺参数如下:年设计能力26万t弧形半径6m铸机流数三机三流铸坯断面150mm×150mm平均拉速2.0m/min连浇炉数8炉流间距1000mm铸坯定尺3~10mm配合作业率60%平均日产量1043t送引锭速度5.0m/min剪切方式火焰切割中间包容量10t中间包控制方式塞棒水口,敞开浇注2设备概况自动控制系统用一台PLC控制公用设备… 相似文献
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连铸机水冷却系统设置的是否合理直接影响了连铸机的正常生产,本文对宝钢集团公司一钢不锈钢连铸车间板坯连铸机冷却水系统作一简要介绍。宝钢集团一钢公司新建连铸车间配有一台不锈钢连铸机,年产合格铸坯72万t;两台碳钢连铸机,年产合格铸坯216.6万t。不锈钢连铸机主要生产的钢种有奥氏体、铁素体、马氏体等不锈钢钢种,碳钢连铸机主要生产的钢种有优质碳素钢、耐大气腐蚀钢、低微合金高强度钢、焊接结构钢等钢种。 相似文献
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全连铸是企业提高经济效益的有效途径。三明钢铁厂炉风系统在钢水回率基本不增加的情况下实现了全连铸生产,并对3座15t氧气顶吹转炉匹配4台3机3流小方坯连铸机工艺过程的优化进行探讨。 相似文献
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针对方圆坯连铸钢水可浇性差,圆坯表面纵裂趋向严重以及因压缩比较小、铸坯内部缺陷难以在轧制工序消除等问题,结合攀钢钒公司新建六机六流方圆坯连铸机的装备特点,从改善连铸钢水可浇性、提高铸坯表面质量和内部质量三个方面,系统研究了方圆坯连铸工艺及相关技术,形成了一系列涵盖连铸工艺与设备的提高钢水质量和铸坯质量的综合控制技术.工业生产应用表明,单中包连浇炉数由原来的平均4~5炉提高到8~10炉;方坯和圆坯表面无缺陷率分别达到98.91%和97.81%;方坯、圆坯中心疏松、中心偏析、中心裂纹等内部缺陷均小于1.0级的综合比例分别达到98.9%和98.5%,铸坯碳偏析指数为0.93 ~1.09.研究结果为方圆坯连铸机顺利投产、稳定生产以及提高铸坯质量和扩大连铸品种提供了重要的技术支撑. 相似文献
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通过研究确定中间包钢水过热度与浇铸拉速的配合、钢水保护浇铸的要求、结晶器振动参数的选择、二次冷却制度与铸坯矫直温度的匹配、结晶器用保护渣等连铸工艺参数,成功探索出一套适合微合金化钢生产的连铸工序控制技术,并成功应用到生产中。 相似文献
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T Imai M Baba M Nishimura M Kakizaki S Takagi O Yoshie 《Canadian Metallurgical Quarterly》1997,272(23):15036-15042
Thymus and activation-regulated chemokine (TARC) is a recently identified CC chemokine that is expressed constitutively in thymus and transiently in stimulated peripheral blood mononuclear cells. TARC functions as a selective chemoattractant for T cells that express a class of receptors binding TARC with high affinity and specificity. To identify the receptor for TARC, we produced TARC as a fusion protein with secreted alkaline phosphatase (SEAP) and used it for specific binding. By stably transfecting five orphan receptors and five known CC chemokine receptors (CCR1 to -5) into K562 cells, we found that TARC-SEAP bound selectively to cells expressing CCR4. TARC-SEAP also bound to K562 cells stably expressing CCR4 with a high affinity (Kd = 0.5 nM). Only TARC and not five other CC chemokines (MCP-1 (monocyte chemoattractant protein-1), RANTES (regulated upon activation, normal T cells expressed and secreted), MIP-1alpha (macrophage inflammatory protein-1alpha), MIP-1beta, and LARC (liver and activation-regulated chemokine)) competed with TARC-SEAP for binding to CCR4. TARC but not RANTES or MIP-1alpha induced migration and calcium mobilization in 293/EBNA-1 cells stably expressing CCR4. K562 cells stably expressing CCR4 also responded to TARC in a calcium mobilization assay. Northern blot analysis revealed that CCR4 mRNA was expressed strongly in human T cell lines and peripheral blood T cells but not in B cells, natural killer cells, monocytes, or granulocytes. Taken together, TARC is a specific functional ligand for CCR4, and CCR4 is the specific receptor for TARC selectively expressed on T cells. 相似文献
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OBJECTIVE: To evaluate effectiveness and safety of a regimen of extended clomiphene citrate (CC) and prednisone for patients who fail treatment with CC alone. DESIGN: Retrospective observational analysis. SETTING: University-based tertiary infertility center. PATIENT(S): Twenty-four anovulatory patients who failed to ovulate after CC 150 mg administered for 5 days. INTERVENTION(S): Treatment consisted of CC given on cycle days 3 through 9 (extended) at a starting dose of 100 to 150 mg/d. Additionally, patients were given prednisone 5 mg orally each night throughout the cycle. MAIN OUTCOME MEASURE(S): Ovulation was confirmed by luteal serum P. Pregnancy was confirmed by rising hCG levels and transvaginal ultrasound. RESULT(S): A total of 60 cycles were available for review. Forty-four of these cycles were ovulatory (73%) and 11 patients (46%) conceived on this therapy. Logistic (two-parameter) pregnancy occurrence over time (cycles) revealed a maximum pregnancy probability of 0.66 and a cycle fecundity of 0.36. No complications of therapy were noted. CONCLUSION(S): Clomiphene citrate-resistant anovulatory patients have high rates of ovulation and pregnancy after treatment with extended CC and prednisone. This therapy offers a potential reduction in cost and risk and should be considered in this group of patients before gonadotropin stimulation or surgery. 相似文献
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连铸坯裂纹成因及预防 总被引:2,自引:0,他引:2
梁伟红 《金属材料与冶金工程》2002,(1):28-31,42
分析了钢的高温力学性能和作用在连铸坯上的各种应力以及化学成分对铸坯产生裂纹的影响,指出裂纹产生的外因是钢水的静压力,热应力,组织收缩应力和其它外力的作用,当这些应力之和超过了钢的高温临界强度和变形量时,就在凝固前沿或凝固壳中产生裂纹,在二冷区凡是增加共内应力,降低强度和塑性的因素将促进裂纹的发生和扩展,裂纹产生的因是钢的高温力学性能和化学成分,提出了防止连铸坯产生裂纹应从两方面考虑,一是工艺参数和设备运转状态,设法降低连铸坯承受的应变和应变速率,二是钢的化学成分,提高钢水纯净度。 相似文献