提高探伤板材堆垛缓冷厚度的研究

针对中厚钢板探伤不合格原因进行分析研究,结果表明:当钢中氢分压超过钢板临界强度时,就会在夹杂物和钢基体间萌生裂纹,并沿钢板中心位置的夹杂物和贝氏体硬化组织带扩展,最终导致钢板探伤不合格。对于正常冶炼的Q345B/C钢种,由280 mm厚度铸坯轧制钢板的堆垛缓冷厚度可以提升至35 mm以上,从250 mm和220 mm厚度铸坯轧制钢板的堆垛缓冷厚度可以提高至25 mm以上;而经过RH真空处理的钢种,钢板堆垛缓冷厚度可以增加到35 mm以上。     

焊缝金属中扩散氢的形成及控制研究进展

 随着焊接技术的广泛应用,焊接接头冷裂纹的形成也备受关注。焊缝中的扩散氢是导致焊缝区产生氢致裂纹的重要原因之一。详细综述了近年来焊缝金属中扩散氢的来源、产生和扩散氢质量分数测定方法的研究进展,总结了影响扩散氢质量分数的有关因素。着重分析了氢在焊接接头的动态扩散行为,对扩散氢的危害和预防措施进行总结,并对相关研究存在的问题和进一步的研究方向进行概括。     

DH36船板探伤缺陷的成因分析和对策

超声波探伤不合是DH36船板钢的主要缺陷之一.通过低倍酸洗试验、金相分析、断面形貌分析,发现了船板内部缺陷的成因,即钢板中存在过量的氢.分析了造成钢板内部氢致裂纹的原因.为消除DH36船板氢致裂纹,有针对性地提出了以RH精炼为主的全流程控氢、降低板坯偏析程度、采用钢板轧制后缓冷等措施.实施后,氢致缺陷消除,钢板质量明显提高.     

安钢厚度不小于25mm钢板探伤检验不合格的原因分析

对探伤不合格的厚度不小于25 mm钢板进行取样,分别做了低倍酸洗、刨削、金相、SEM及能谱分析,分析认为探伤不合格的主要原因是中心偏析分层、内部裂纹、中心部位的氢致裂纹、大颗粒外来夹杂(夹渣)。在生产压缩比小于6.0的宽厚规格钢板时,应围绕钢水质量、板坯低倍质量、缓冷时效(≥48 h)、轧后时效(≥24 h)有针对性地选择工艺路线,其中钢水质量主要为钢中氢的质量分数应控制在2.0×10-6以下,硫的质量分数控制在0.010%以下,氧的质量分数控制在25×10-6以下;板坯低倍质量主要由过热度(15~25℃)、拉速(恒拉速)、动态配水、动态软压下、液面控制(±4 mm)及设备工况等综合工艺条件决定。     

HTP技术在高强度特厚板生产中的应用

 借助于热模拟、数值模拟的方法,采用添加铌、锰、铬、硼,不含钼的低成本合金设计,通过2种铌质量分数（0.09%和0.05%）钢种的对比,探讨了HTP工艺技术在厚度小于等于100mm、屈服强度大于等于600MPa级别高强度钢中的应用。试验结果表明：采用HTP+回火工艺,可提高钢板的未再结晶温度;改善钢板厚度方向均匀性和钢板的心部冲击韧性,钢板表面和厚度1/4处的组织多为板条贝氏体组织,芯部组织为粒状贝氏体+黑色的珠状组织。     

“埋弧焊接+真空电子束焊接”工艺生产200mm厚度Q345D-Z35钢板的研究

采用"埋弧焊接+真空电子束焊接"新工艺,通过成分设计、连铸坯料复合、高温低速大压下轧制、轧后钢板缓冷、正火处理等手段,成功研发了200 mm厚度Q345D-Z35钢板,钢板各项性能优良,内部质量良好。     

低合金热轧中厚板探伤不合原因分析与改善

借助金相显微镜、测厚仪和定氢仪等设备,对低合金热轧中厚板探伤不合缺陷位置进行了系统分析。认为钢中气体氢在夹杂物缺陷处聚集,并且钢板缓冷工序异常,导致气体、应力释放不均匀,缺陷位置应力集中开裂,是造成探伤不合的主要原因。通过增加RH真空处理,改善钢板堆垛缓冷条件,低合金中厚板探伤合格率提升至100%。     

S355ML钢板边部微裂纹的原因分析与控制

莱钢试制S355ML钢板,试制钢板下表面出现微裂纹。取厚度35 mm的S355ML头部边样,通过金相分析、扫描电镜及成分分析,发现裂纹深度在40～80μm,裂纹末端较钝,内部基体被氧化铁皮包裹,周边存在Si-Mn氧化物析出,认为连铸坯的角部横向裂纹是引发钢板微裂纹的原因。结合莱钢厚板连铸产线,严格控制过热度、拉坯速率及结晶器非正弦有序振动,并对连铸坯缓冷精整,保证连铸坯氧化铁皮及折叠处吹扫清理效果。采取相应措施后,有效避免铸坯角部横裂纹的产生,确保了S355ML钢板质量。     

受热不均匀对低碳钢SAE1010板材组织及成形性能的影响

为了研究退火过程受热不均匀对板材组织及成形性能的影响规律,对热轧态SAE1010低碳钢板进行冷轧及连续退火,分析热轧态、冷硬态及退火态钢板边部和芯部的显微组织,分别对退火态钢板边部和芯部试样进行拉伸和折弯试验。结果表明,热轧态试样少量岛状珠光体分布在铁素体晶界处,边部组织晶粒尺寸小于芯部,珠光体中部分片层渗碳体退化为球状。冷硬态板材组织沿轧制方向呈现明显的晶粒破碎特征,退火态边部组织存在较多的大晶粒和粒状渗碳体团,芯部组织较为均匀细小。退火态板材芯部材料伸长率高于边部而强度低于边部,经180°折弯后芯部钢板无开裂而边部出现裂纹。退火温度均匀性对于SAE1010低碳钢板组织和性能具有重要的影响。     

低Mo耐火建筑用钢Q345FRE开发试验研究

综合考虑合金元素对耐火建筑用钢高温力学性能的作用,在实验室采用500 kg多功能真空感应炉完成低Mo成分体系Q345FRE耐火钢热轧基料的制备,使用550 mm热轧实验机组完成15 mm厚度耐火建筑用钢板的轧制和冷却。比较轧后水冷和空冷两种工艺,常温力学性能均满足GB/T 28415—2012《耐火结构用钢板及钢带》标准要求。轧后空冷钢板的高温性能未满足国标要求,而轧后水冷钢板的高温性能满足国标要求,主要原因为水冷钢板高温组织相比空冷显著细化。通过合适的成分设计、轧制和冷却工艺,实现了15 mm厚度耐火建筑用钢Q345FRE的成功试验开发。     

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.