铈、钼和磷在钢中的晶界偏聚行为与高温回火脆性

本文研究了铈和钼对Ni-Cr-Mo钢在500℃长时间回火过程中的脆化倾向的影响。用AES测定了磷、镍和钼的晶界偏聚,用TEM+EDAX分析了铈的晶界偏聚浓度,测定了钢的FATT_50的变化。结果表明,铈和磷在一定浓度下形成Ce-P化合物,铈和钼综合合金化可减弱中碳CrNi3Mo钢长期回火脆化倾向。文中讨论了铈、钼和磷在钢中的相互作用。     

加钛的镍铬钢回火脆性的锑非平衡晶界偏聚机理

回火脆性的溶质非平衡晶界偏聚机理的本质是溶质非平衡晶界偏聚的临界时间引起回火脆性的临界时间.在此基础上,研究了加钛的镍铬钢回火脆性的临界时间、回火脆性的极大值和充分回火后2.7J脆-韧转变温度随回火温度的变化,并结合锑的非平衡晶界偏聚量的测量结果,论述了加钛的镍铬钢中回火脆性的锑的非平衡晶界偏聚机理.     

35MnSiB弹簧钢脆性的研究

研究了３５ＭｎＳｉＢ钢冲击和拉伸性能以及回火温度对其性能的影响；借助于扫描电镜及俄歇谱仪，对断口形貌和晶界成分进行了分析。试验结果表明；试样的脆性断口基本上是沿晶断口，在晶界上有磷，硅的偏聚，有碳化物和氮化物存在；试样的尺寸和表面状态对塑性有较大的影响，４００℃回火可显著改善试样的塑性和韧性。     

晶间脆性断裂的非平衡偏聚机理研究

 中温脆性、回火脆性是困扰材料学界百年的两大晶间脆性难题,其发生机理一直是材料科学与工程学界研究的热点。根据溶质非平衡偏聚恒温动力学特征,总结出了中温脆性的非平衡偏聚机理。另外,依据溶质非平衡偏聚的临界时间现象,综述了回火脆性的非平衡偏聚研究最新进展。通过对以上两种晶间脆性断裂发生机理的分析发现,他们都是由溶质的非平衡偏聚临界时间引起的。     

合金元素对Cr-Mo钢第二类回火脆性影响研究综述

 对于一些长期在中温条件下服役的Cr-Mo钢(2.25Cr1Mo),由于钢中P、S等有害杂质元素在服役过程中不断向晶界偏聚,降低了晶界结合力,致使该类钢出现第二类回火脆性这一关键问题。为了探寻降低这类Cr-Mo钢第二类回火脆性倾向的有效方法,提高材料安全服役可靠性,从溶质元素偏聚机制出发,总结分析了合金元素晶界偏聚及改善钢第二类回火脆性的内在本质,重点归纳了几种常见元素的晶界偏聚行为及其对钢回火脆性的影响,同时还客观分析了理论计算和试验研究在阐释合金元素对晶界脆性影响存在差异的主要原因,期望能为中温用钢长期服役过程中存在的回火脆性提供一些有效控制方法,也为合金元素晶界偏聚行为的研究提供一些参考。     

磷在钢回火脆性发展时的非平衡偏聚及钼的影响

用俄歇能谱仪和扫描电镜研究了中碳钢和含钼中碳钢在回火脆性发展过程中Ｐ在晶界上的偏聚。发现在４８０ ℃回火时,两种钢均在晶界出现Ｐ的浓度峰值。含钼中碳钢中的Ｍｏ 减小了晶界断裂比例,但并不改变Ｐ的浓度峰值。同时还观察了Ｓ、Ｃ、Ｍｏ 等组元在晶界的偏聚。Ｐ在晶界的浓度峰值可以用磷－空位复合体的非平衡偏聚机制加以解释。     

X120管线钢回火过程中断口分离问题研究

针对一种高强度X120管线钢高温回火条件下出现的夏比冲击试样断口分离现象。利用扫描电镜、透射电镜及冲击试验机等,从磷、硼、锰等元素的偏析,晶界处第二相如碳化物、合金析出物等的析出及长大角度进行讨论分析。研究结果表明：随回火温度升高,断口分离加剧,分离平均长度及数量增加。夏比冲击功降幅达60％;断口分离先于主断口形成,导致试验钢表面能增加,刚度、主断口裂纹形成功及裂纹扩展功下降;磷、硼、锰等元素在晶界偏聚引起的回火脆性导致分离裂纹产生,夹杂物对分离起促进作用,尺寸较大的第二相弱化了晶界强度。     

微量镓对低碳钢低温韧性影响的研究

对含微量镓(0.004～0.055％)的低碳钢(C～0.13％)在各种处理状态下的低温系列冲击实验,光学金相和透射扫描电镜观察以及化学成分定位X射线能谱分析发现,微量镓能在一定程度上阻碍磷在晶界上的偏聚,从而明显降低钢的脆性转折温度,提高钢的低温韧性。实验结果和磷在钢中的化学,弹性交互作用理论计算分析结果相符。     

Gleeble模拟热轧工艺对磷非平衡晶界偏聚的影响

 采用Gleeble 3500热模拟试验机研究了轧制和卷取温度下磷元素晶界偏聚与热轧板高温热塑性的关联机制。研究结果表明,含磷钢中磷元素晶界偏聚符合空位-磷原子复合体非平衡共偏聚理论,800 ℃以上轧制温度对磷元素晶界偏聚引起的钢板脆性影响较小,而在500～650 ℃温度范围存在磷元素偏聚导致的热塑性低谷区,且在该温度区施加1%拉伸预应变将加剧磷元素晶界偏聚和钢板脆性。因此,本试验成分含磷钢热轧生产中卷取温度设定应避免550 ℃塑性低谷。     

回火温度对Q450EWR1低温冲击韧性的影响

通过力学性能测试,并结合金相显微镜和扫描电镜观察,分析回火温度对Q450EWR1低温冲击韧性的影响。研究结果表明,通过700℃回火2h能够明显提高Q450EWR1低温冲击功,在200~400℃回火的低温冲击功较热轧态无明显改善,而在500和600℃回火出现明显回火脆性。     

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.