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为了探究一种超低碳含铌钢(0.002C-0.52Nb)的相变机制及动力学,采用热膨胀法研究其连续冷却转变行为,通过光学显微镜及扫描电镜观察组织转变特征及规律,并用改进的JMA方程计算相变界面移动速率。结果表明,试验钢在3~30℃/s冷速范围内的组织具有块状相变的特征,即新相铁素体晶界呈不规则的锯齿状,可以跨越原奥氏体晶界生长;相变动力学计算结果显示,同一冷速下的界面速率基本稳定,3、5、10、30℃/s对应的平均界面移动速率分别为(0.65、1、1.7、6.2)×10~(-5)m/s,相界面移动速率随冷速增加而提高,与冷速的增加比例基本相当,界面控制的动力学方程基本适用,铌溶质在一定程度上影响了相界移动速率。 相似文献
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利用高温共聚焦激光扫描显微镜对GH5188合金在冷速为10~200℃/min条件下的凝固过程进行动态原位观察,并研究了冷速对GH5188合金凝固过程、凝固组织及析出相的影响。结果表明,GH5188合金的凝固过程为缓慢凝固-快速凝固-缓慢凝固过程,冷速越大,峰值凝固速度越大。冷速影响合金凝固温度,随着冷速的增加,凝固温度逐渐降低,冷速的增加使合金凝固后二次枝晶间距减小,析出相尺寸更均匀细小,有利于减少合金凝固过程的裂纹敏感性,获得了不同冷速下合金二次枝晶间距的预测公式。 相似文献
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《稀土》2015,(1)
利用L78 RITA热膨胀相变仪研究了不同冷速下稀土对低碳高铌钢相变行为的影响,并结合金相法绘制了加稀土和未加稀土两种成分试验钢的连续冷却相变曲线,分析了稀土对连续冷却组织的影响规律。试验结果表明,稀土加入低碳高铌钢后使连续冷却相变曲线向右移动,在相同冷速下显著降低了奥氏体向铁素体转变的开始温度,并且随着冷速的增加使降低程度增大。冷速从0.1℃/s增加到15℃/s时,加稀土的低碳高铌相变开始温度点下降了90℃,而未加稀土的下降了52℃;另一方面,稀土对低碳高铌钢在0.1℃/s到1℃/s冷速下的组织有较大影响,促进了针状铁素体的转变,并能在冷速增至5℃/s后使其更易获得板条状贝氏体组织。 相似文献
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通过CCT曲线的测定,研究了72A钢在不同冷速条件下的金相组织及硬度变化规律。连续冷却速度不同,发生相转变的温度和组织也不同,随着冷速的增加,开始相转变的温度降低,奥氏体过冷度增加;在冷速为0.1~15℃/s时,随着冷速的增加,珠光体基体的硬度逐步增加,当冷速在15~30℃/s区间变化时,珠光体基体的硬度基本不变。 相似文献
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实验结果表明,M17铸造高温合金(%:0.16C、8.79Cr、5.79A1、4.93Ti、3.29Mo、15.20Co、0.78V、0.015B、0.073Zr、0.002S、0.001P、0.001 1O、0.001 0N)经25 kg真空感应炉返回重熔后,Si含量随重熔次数的增加而略有增加,合金中主要元素和其它杂质元素S、P、H的含量变化不大,而氧、氮略有增加;合金中初生碳化物由新合金中的草书体逐渐向返回合金块状转变,初生碳化物的遗传性堵塞合金凝固时的补缩通道,使返回料合金的疏松倾向增大,高温塑性下降较大。 相似文献
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正Shijiazhuang City will build the world’s biggest replacing-copper-with-aluminum cable production base,the annual output value can reach 100 billion yuan,in the future it will develop replacing-copper-with-aluminum highend industry cluster.This piece of news was learned by the reporter at the Rare Earth highiron Aluminum Alloy[Nonferrous Business Opportunity:Aluminum alloy door]Cable Conductor New Technology Application Seminar held at the provincial capital. 相似文献
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《China Nonferrous Metals Monthly》2014,(12)
正Since the beginning of Chongqing’s upgrading to a municipality directly under the Central Government,Chongqing City has established direct friendly relationship with Almaty,Kazakhstan,and carried out a series of cooperation in commerce and trade,and culture 相似文献
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《China Nonferrous Metals Monthly》2014,(10)
正"For each tonne of aluminum being produced,the upstream enterprise on the aluminum industrial chain will suffer loss about 2000yuan."Said Liang Xiao,Deputy Director of Pingguo Industrial Park Management Committee under the Guangxi Baise City,one of the four major aluminum industry bases in China,on August 11.Extending aluminum 相似文献
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正Immediately after the news that Chinalco transferred 58%stock equity of Yunnan Copper Group to its wholly-owned subsidiary China Copper Corporation Limited free of charge was disclosed on July 9,many individual investors couldn’t help but to think:Does it mean China Copper Corporation Limited will assemble assets for overall listing?At present,among main copper business companies under China Copper Corporation 相似文献
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正At the press conference recently held by the National Development and Reform Commission under the theme"Deepen Reform in Investment AuditApproval System",when answering questions from reporters,Huang Min,Director of the Department of Fixed Assets Investment of the National Development and Reform Commission,said that in the future it would continue to intensify efforts in geological prospecting,and actively guide social capital to enter this field. 相似文献
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正Recently,Guangxi Metallurgical Research Institute,a subsidiary of Guangxi Nonferrous Metals Group,completed survey on laterite and related manufacturers in the region,by combining the current development status of laterite both at home and abroad,it compiled Guangxi’s first"Research Report on the Development of Guangxi Nickel Industrial Chain"which adopted laterite as the study subject.This report expounded on the current 相似文献
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