含铌钢板坯角横裂纹的控制

采用金相显微镜和扫描电镜分析了含铌微合金化钢铸坯角部横裂纹的形成原因.发现矫直区铸坯角部温度位于该钢种第Ⅲ脆性温度区间内;拉速波动导致角部温度变化较大;二冷喷嘴状况不好导致两边角部温度相差较大.采用提高拉速、矫直区铸坯角部喷嘴遮挡等"热行"方法后,铸坯角部温度明显提高,铸坯的角横裂纹的发生率大大降低,但铸坯中心偏析恶化.采用增加角部喷嘴的"冷行"方法后,铸坯角部温度明显降低,铸坯的角横裂纹和中心偏析大大改善.     

含硼钢板坯边角裂纹的成因与控制

 采用金相显微镜、扫描电镜和Gleeble-3800热模拟试验机分析了含硼微合金化钢板边角部表面裂纹的形成原因。发现二冷矫直区铸坯内弧边角部温度位于该钢种第3脆性温度区间内,拉速较低和二冷水表及喷嘴布置不合理导致了内弧两边角部温度较低。采用提高拉速、遮挡矫直区铸坯角部喷嘴和适当降低二冷水表等“热行”方法后,结合调整动态轻压下参数使得铸坯角部温度明显提高,铸坯的边角裂纹和内部质量均得到显著改善。     

利用倒角结晶器消除连铸板坯的角横裂纹缺陷

 提出一种用以解决连铸板坯角横裂纹缺陷的倒角结晶器技术。倒角结晶器的数值仿真和工业化试验表明：倒角铸坯在连铸矫直区角部温度可以提高70℃以上,能够避开钢的高温低塑性区;同时,倒角的特殊的结构形式可以降低铸坯角部的Z向应力,有助于控制角横裂纹缺陷。     

薄板坯连铸中碳钢角横裂缺陷成因及控制

 针对薄板坯连铸中碳钢边角部出现的角横裂纹缺陷,通过典型中碳钢（50CrV4）缺陷试样的金相分析、热塑性分析和铸坯二冷模拟仿真计算等方法,确定了原工艺条件下典型中碳钢铸坯边角部在铸机弯曲和矫直处的温度为850 ℃、处于第Ⅲ脆性区（650～945 ℃）是造成铸坯边角部裂纹的主要原因。结合武钢CSP铸机工艺特点,提出了连铸高拉速4.0～4.2 m/min,二冷前段强冷、后段和边部弱冷以及提高铸机设备精度等控制措施。各项措施实施后,中高碳钢铸坯边角部温度显著提升,热轧板表面横裂纹基本消失,各项性能满足客户要求。     

船板钢CCSA板坯连铸二冷系统优化

针对船板钢CCSA板坯角部横裂纹发生率偏高的现象,在高温力学性能测试和铸坯表面温度测量的基础上,分析认为二冷系统造成的铸坯温度分布不合理是其主要成因.采取两项措施来优化二冷系统:改变部分喷嘴型号并调整喷嘴布置;利用修正的板坯连铸凝固传热数学模型对二冷配水进行优化.试验结果表明,二冷系统优化后,铸坯角部温度有了较大提升,角部横裂纹发生率由3.7%降至0.41%.     

Q235连铸板坯角部裂纹形成机理及控制

为了解决Q235连铸坯角部裂纹缺陷,采用缺陷微观形貌分析和工艺参数影响规律统计分析相结合的方法研究了缺陷形成原因。结果表明：铸坯矫直前AlN大量析出是其产生角部裂纹的主要原因。基于AlN析出热力学分析,随着钢中铝和氮含量降低,AlN开始析出的温度下降,矫直温度范围内AlN析出量显著减少。考虑实际生产,确定了降铝措施作为改善铸坯角部裂纹缺陷的控制措施,现场应用后,Q235连铸板坯角部裂纹指数由3.59下降到0.19,钢中铝的质量分数平均下降126.64×10^-4%,合金使用成本降低。     

包晶钢连铸坯角部裂纹缺陷产生原因分析与预防

针对中碳包晶钢凝固过程中铸坯角部裂纹缺陷问题,采用低倍酸洗、金相显微镜和扫描电镜能谱分析仪等手段,结合生产工艺,对裂纹缺陷产生原因进行详细分析。结果表明:裂纹主要产生于铸坯角部振痕波谷应力比较集中位置,主要以晶间裂纹为主。通过采取优化钢水化学成分和连铸二次冷却工艺,严格控制辊缝精度和提高矫直段前铸坯边角部温度等措施,可以有效预防铸坯角部裂纹缺陷产生,经统计,裂纹缺陷率由原来的1.27%降低到了0.24%。     

直弧连铸机板坯皮下横裂纹的形成原因及预防

论述了直弧型板坯连铸机生产硅铝镇静钢时产生皮下横裂纹的机理及原因,并找出了产生皮下横裂纹的主要原因,w(Al)高及铌增加了铸坯的裂纹敏感性.提高矫直温度和铸机二冷段设备精度,选择合适的结晶器保护渣,有利于消除皮下横裂纹.     

板坯角部裂纹分析与控制

对天钢板坯角部裂纹进行研究分析,结果表明:铸坯凝固过程中晶界出现了B(CN)和Al N等二相粒子聚集,同时,由于在铸坯初凝期奥氏体晶界生成铁素体膜,导致板坯角部区域的延展性显著降低。受二者的共同作用,当板坯通过矫直区时,受到矫直应力作用而产生裂纹。通过控制钢中氮含量、降低结晶器水量及二冷水量,提高铸坯角部的矫直温度,改善高温力学性能,使板坯角部裂纹得到有效控制。     

攀钢板坯连铸机不同断面铸坯角部横裂纹分析

通过喷嘴性能测试、重熔凝固冷却实验和计算机仿真软件计算,研究了攀钢不同断面板坯角部冷却情况对铸坯角部横裂纹的影响.研究表明:对于1160、1080和1250mm三个断面尺寸的铸坯,较强的冷却使角部温度较早低于A₃温度,矫直前沿奥氏体晶界形成大量膜状先共析铁素体,矫直时容易沿奥氏体晶界形成角部横裂纹.为解决角部横裂纹问题,通过改变铸坯表层组织来控制铸坯角部横裂纹的产生,并将其应用于攀钢现场生产.     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.