热轧船板表面裂纹的成因分析

通过对裂纹处显微组织的分析,研究了热轧船板表面裂纹产生的原因。结果表明,船板表面裂纹来源于铸坯表面的原始微裂纹和钢中低熔点合金元素引起的轧件不均匀变形,据此提出了相应的改进措施。     

含铌、钛船板钢中板表面微裂纹研究

对含Nb、Ti船板钢中板表面微裂纹的形成机理进行了研究，结果表明：中板表面微裂纹不是轧制时新产生的裂纹，而是由铸坯微裂纹扩展形成的，铸坯裂纹是在结晶器中形成的沿晶界裂开的表面微裂纹；影响铸坯微裂纹形成的主要因素是钢中铌，钛、铝含量和Cu等低熔点元素含量以及各种应力的作用。     

结晶器厚度方向锥度对铸坯质量的影响

从铸机结晶器参数入手，对比了不同类型铸机所生产铸坯表面纵裂纹的差异。认为结晶器厚度方向锥度小是导致铸坯表面产生纵裂纹的主要原因，锥度越大越有利于降低铸坯表面纵裂纹的发生率。通过研究结晶器的发展过程指出，在结晶器设计过程中，厚度方向的锥度应满足钢种的凝固收缩，尽量减少气隙，改善传热，降低铸坯缺陷。     

Φ 40 mm螺纹钢横肋裂纹的分析与控制

分析了500B Φ40mm钢筋在生产过程中出现的横肋末端微裂纹产生的原因。通过对相关铸坯进行表面质量、低倍组织及金相组织检验,认为连铸二冷水冷却不均匀形成了铸坯角部裂纹,经轧制后导致了钢筋微裂纹的产生。通过调整二冷水冷却工艺参数和喷淋管角度、优化钢筋孔型等措施,消除了500B Φ40 mm螺纹钢的表面微裂纹。     

喷嘴喷淋距离对连铸小方坯二冷均匀性的影响

研究了不同喷淋距离下连铸小方坯二冷喷嘴的水量分布,建立了凝固传热模型分析了82B钢连铸坯的热行为。该模型特别考虑了二冷区铸坯表面宽度方向的水流密度分布,并根据铸坯表面测温结果进行了模型校正。采用凝固传热模型研究了喷嘴喷淋距离对连铸二冷均匀性的影响。结果表明:喷嘴喷淋距离的增加有助于提高二冷水横向分布的均匀性,导致铸坯表面温度横向均匀性降低、纵向均匀性提高。这些效果有助于改善铸坯内部裂纹,但是会对角部裂纹产生不利影响。在二冷区前段喷嘴采用低喷淋距离,二冷区末段采用高喷淋距离,既可以提高铸坯角部温度,又能降低表面最大回温速率,有助于同时改善连铸坯角部和内部裂纹。在此基础上,提出了一种连铸小方坯二冷喷嘴布置方式,即二冷区每段喷嘴喷淋距离沿拉坯方向逐渐增加,该方法有助于提高连铸坯“纵?横”冷却均匀性。      

50钢板表面龟裂纹的形成原因与控制

针对50钢200 mm厚连铸坯轧制钢板的严重表面龟裂(发生率7.92%)问题，采用扫描电镜、光谱分析等方法，研究了表面龟裂的形貌、分布、成分等特征。结果表明，表面龟裂随机出现在钢板上，宽度方向上表面龟裂没有固定位置，裂纹深度较浅，两边呈现高亮度组织和氧化原点特征，光谱分析显示裂纹处碳含量比基体高，增碳质量分数0.2%～0.3%。分析认为，连铸过程中铸坯局部增碳，在加热、粗轧过程中热塑性不均匀而导致裂纹及明显的高温氧化特征。根据连铸保护渣增碳机理，优化了结晶器渣线调整模式、铸坯拉速、水口形状、结晶器保护渣成分等连铸工艺参数，有效降低了连铸坯表面局部增碳及钢板龟裂的发生率。     

55钢150mm×150mm连铸坯皮下裂纹分析与工艺改进

55钢(/%:0.52～0.60C,0.17～0.37Si,0.50～0.80Mn,≤0.035P,≤0.035S)的150 mm×150 mm连铸坯轧钢加热炉加热后存在表面纵向裂纹缺陷。采用金相显微镜对铸坯皮下裂纹缺陷进行分析,结果得出:由于二次冷却不均匀和有害元素Pb在晶界富集导致铸坯皮下产生细小裂纹并扩展长大。通过对二次冷却喷淋系统优化及降低钢水有害元素Pb含量,改善二冷段喷淋冷却效果,提高铸坯冷却均匀性,提高铸坯晶界强度,结果表明:铸坯缺陷明显改善,轧材一次探伤合格率从45%提高到93%。     

55钢150 mm x 150 mm连铸坯皮下裂纹分析与工艺改进

55钢(/%:0.52～0.60C,0.17～0.37Si,0.50～0.80Mn,≤0.035P,≤0.035S)的150 mm×150 mm连铸坯轧钢加热炉加热后存在表面纵向裂纹缺陷。采用金相显微镜对铸坯皮下裂纹缺陷进行分析,结果得出:由于二次冷却不均匀和有害元素Pb在晶界富集导致铸坯皮下产生细小裂纹并扩展长大。通过对二次冷却喷淋系统优化及降低钢水有害元素Pb含量,改善二冷段喷淋冷却效果,提高铸坯冷却均匀性,提高铸坯晶界强度,结果表明:铸坯缺陷明显改善,轧材一次探伤合格率从45%提高到93%。     

连铸坯热装热送工艺研究和钢板质量改进措施

本文通过对热送铸坯钢板表面裂纹产生的原因进行分析和研究,发现热送铸坯钢板表面裂纹主要在轧制环节中产生;降低铸坯加热炉温度,减少铸坯加热时间等措施可使热装热送铸坯轧制钢板裂纹得到有效控制。     

SM490A-B铸坯角部裂纹的分析

用金相显微镜、扫描电镜及能谱仪分析低碳含硼钢SM490A-B铸坯角部裂纹的特征和成因。结果表明:铸坯角部裂纹主要为横裂纹,裂纹沿发达的柱状晶和粗大的奥氏体开裂,铁素体膜和裂纹内的氧化铝夹杂促进了裂纹的萌生和扩展。冷却不均匀和高的过热度造成奥氏体晶粒粗大,且不同区域的铸坯角部组织不一致;铸坯内外大的温度梯度使柱状晶发达。     

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.