开轧温度对42CrMo4钢轧制动态组织变化影响的有限元模拟

应用LARSTRAN/SHAPE有限元模拟软件对42CrMo4合金钢箱形孔型轧制过程进行三维热力耦合有限元模拟.用粘塑性有限元理论模拟轧制过程各时间离散步的局部量包括等效应力、等效应变、等效应变速率、温度分布等,由此计算动态再结晶和晶粒大小的变化.通过模拟研究得出开轧温度≥1 050℃时,42CrMo4钢动态再结晶显著增加,生产42CrMo4钢棒材的合适开轧温度为1 050～1 100℃.     

42CrMo钢表面脱碳行为研究

利用S60/58507型高温热重分析仪研究了加热温度对42CrMo钢脱碳的影响，分析了脱碳组织形貌规律，对传统脱碳模型进行了修正。结果表明，总脱碳深度随加热温度的升高而增加。当加热温度为900℃时，42CrMo钢表面出现完全脱碳层和部分脱碳层，当温度为950℃及以上温度时，42CrMo钢表面只出现部分脱碳层。部分脱碳层中铁素体沿晶界分布，形成网状铁素体组织。由于合金元素的作用，传统的脱碳模型不能适用于42CrMo，修正之后的模型能够较为准确地预测42CrMo钢的总脱碳深度。     

1300 MPa级高强度螺栓钢

在常用高强度螺栓钢42CrMo的基础上研究开发出一种强度级别更高的高强度螺栓钢42CrMoVNb。试验结果表明,新开发钢的奥氏体晶粒长大趋势明显小于42CrMo钢,具体微细的显微组织,在约550℃以上温度回火时析出合金碳化物而产生二次硬化,具有良好的强韧性配合;其耐延迟断裂性能,缺口敏感性和冷加工性能均优于42CrMo钢,用新开发钢试制的高强度螺栓已通过了汽车道路考核试验。     

高强度螺栓用钢42CrMo（B7）的研制

高强度螺栓用钢42CrMo（B7）要求高强度的同时,还要求良好的抗低温脆性以及严格的晶粒度。通过Cr、Mo合金化、控制钢中碳含量和残余元素以及控制轧制控制钢中的第二相,实现了细晶强化和提高钢的低温性能。检验表明,钢的实际晶粒度为6～8级,各类夹杂物在0.5级以下,AkV达到27J（-100℃）,力学性能完全满足用户要求。     

正火预热处理对42CrMo曲轴钢调质后的组织与性能影响

利用金相显微观察及力学性能分析,研究调质处理、正火+调质热处理对42CrMo曲轴钢组织与性能的影响。结果表明,经过860℃淬火+580℃回火处理后,曲轴钢基体组织为回火索氏体,但轴颈心部区域白色铁素体数量较多且晶粒粗大、分布不均。其力学性能为抗拉强度997～1 211 MPa,屈服强度990～1 204 MPa,伸长率11%～13%,断面收缩率40%～48%,冲击功72～90 J。而在调质热处理前增加一次(880℃空冷)正火预处理后,42CrMo曲轴钢的显微组织更趋均匀化,其力学性能为抗拉强度1 100～1 220 MPa,屈服强度1 107～1 188 MPa,伸长率13%～15%,断面收缩率50%～56%,冲击功83-91 J。因此,880℃空冷正火预处理+860℃淬火与580℃高温回火是42CrMo曲轴钢优化的热处理工艺。     

降低CrMo钢硬度的研究及改进措施

为降低CrMo钢热轧硬度,进行了CrMo钢连续冷却相变试验,研究了高温相变时间、优化了轧制工艺、控制CrMo钢加热温度,采用了冷床加保温罩等措施,将CrMo钢的热轧硬度控制在了220~260 HB。     

韶钢转炉冶炼42CrMo钢的生产实践

韶钢通过设备改进及工艺优化,产品实现了从普通钢向特殊钢的转型,在42CrMo钢的冶炼过程中采取转炉高拉碳、精炼渣系优化、真空脱气等工艺措施,并在连铸工序对连铸参数进行控制,最终生产出性能等方面完全满足客户高质量要求的42CrMo钢.     

石钢大规格棒材芯部质量的控制

针对石钢大规格棒材轧制过程中芯部存在的孔隙性缺陷,建立三维有限元数值模型,分析了Φ150mm42CrMo棒材轧制过程中的工艺参数（压下量、摩擦系数、轧件温度、轧制速度等）对棒材芯部质量的影响。     

35CrMo、42CrMo锻造用钢坯的试制

自从引进连铸精炼设备后,包钢开始着手开发新钢种的工作,1997年11月起到1998年3月间,采用不同生产工艺,试制冶炼35CrMo钢5炉,42CrMo钢4炉,分别轧制成几种断面尺寸的锻造钢坯,经检验各项指标完全合格.本文着重阐述了产品试验过程及结果,并对其原因作了进一步的分析.     

轻压下和拉速对42CrMo钢410 mm x 530 mm铸坯轧成Φ195 mm材的低倍和中心C偏析的影响

对比试验了铸坯的轻压下量(0～8 mm)及拉速(0.42～0.49 m/min)对42CrMo钢Φ195 mm轧材低倍组织和偏析的影响。结果表明,在现有工艺条件下,42CrMo钢过热度控制在20～30 ℃,二冷比水量0.30 L/kg,结晶器电搅100A/1.5 Hz,末端电搅400A/8 Hz,连铸拉速控制在0.49 m/min,总压下量6～8 mm,能有效改善42CrMo钢轧材的内部质量。     

熔炼次数对M17返回料合金成分、组织和性能的影响

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。     

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.