回火温度对40 Cr钢组织和性能的影响

通过拉伸试验、金相组织检验、洛氏硬度及冲击试验,研究分析了450～690℃回火温度下,40Cr钢组织和性能的变化。结果表明,随着回火温度的升高,40Cr钢的抗拉强度、屈服强度、屈强比及硬度单调下降,断后伸长率、冲击吸收功单调上升;回火组织主要为回火索氏体,其形态由保留少量的马氏体形向细密形及粗大形转变;抗拉强度、屈服强度与回火硬度成良好的线性关系。510～660℃回火时,40Cr钢冲击吸收功随回火硬度的升高逐渐降低,且回火硬度为27～29 HRC时降幅最大。     

回火温度对25Co15Ni11Cr2MoE钢力学性能的影响

采用力学性能试验和金相显微镜(OM)、扫描电子显微镜(SEM)等显微组织分析方法对一种高Co-Ni含量二次硬化钢25Co15Ni11Cr2MoE淬火后,经200~750℃回火后的力学性能和冲击断口形貌的变化规律进行了分析研究,结果表明:25Co15Ni11Cr2MoE试验钢淬火+回火后具有明显的二次硬化效应,在400~495℃范围内,回火后的硬度值均高于淬火态硬度值;随着回火温度的提高,钢的抗拉强度、屈服强度和硬度均不断增加,在470℃回火后,试验钢的硬度和抗拉强度均达到了极大值57.3HRC和2160MPa;而冲击韧性值随着回火温度的升高先降低,在430℃达到极小值,随后逐渐提高,并在510℃回火后达到极大值。建议25Co15Ni11Cr2MoE钢的最佳热处理制度为:950℃×1h油冷+(-73℃)×1h空气中升温至室温+495℃×5h空冷,此时试验钢具有最佳的强韧性匹配。     

回火温度对20SiMnMo高强度钢微观组织与力学性能的影响

采用光学显微镜、扫描电子显微镜、洛氏硬度计、万能力学试验机以及冲击试验机研究了950℃淬火220℃、240℃、260℃、280℃、300℃和320℃3 h回火试验对20SiMnMo高强度钢（/%:0.22C,0.80Si,1.00Mn,0.40Mo,0.72Cr,0.20Ni）微观组织和力学性能的影响。结果表明,随着回火温度的升高,试验钢的硬度、强度不断下降,伸长率、室温冲击功先升高再降低。当260℃回火时,试验钢具有均匀细长的板条马氏体组织,其强塑韧综合力学性能最佳:硬度值44.8HRC、AKV2冲击功75.3 J、抗拉强度1 278 MPa、屈服强度1 210 MPa、伸长率15.5%。     

热处理对冷作模具钢Cr8WMo2V2SiNb组织和力学性能的影响

研究了1000～1240℃淬火,以及1100℃淬火+200～580℃回火对25 kg真空感应炉冶炼的Cr8WMo2V2SiNb钢(%:0.96C、1.11Si、7.79Cr、1.79Mo、2.16V、0.96W、0.60Nb)Φ13 mm锻材的淬火组织和晶粒度,淬-回火组织、硬度和冲击功的影响。结果表明,Cr8WMo2V2SiNb钢1 100℃淬火后的硬度HRC值为64.5;1100℃淬火+520℃回火有明显二次硬化效应,硬度达到最大值-HRC62.5,并有较好的韧性,冲击功为8.7 J。     

热处理对5Cr5MoSiV钢组织和性能的影响

研究了淬火和回火温度对全断面隧道掘进机盘形滚刀用5C15MoSiV钢(0．50～0．55C，4．5～5．5Cr，0．8～1．2Si，0．8～1．5Mo，0．6～1．2V)组织、硬度和耐磨性的影响，该钢在1020℃淬火 500℃两次回火可获得最高的硬度；而在1060℃淬火 530℃两次回火可获得较好的耐磨性。     

回火温度对渗碳钢18Cr2Ni4WA组织和硬度的影响

为满足用户加工HBW硬度值≤269的需要,降低18Cr2Ni4WA钢Φ60 mm材硬度,利用连轧厂实际辊底式退火炉进行了630～750℃5h炉冷至500℃空冷的回火试验,并借助金相显微镜对18Cr2Ni4WA钢不同回火温度下的组织进行了分析,以确定最佳的回火温度。结果表明,18Cr2Ni4WA钢随回火温度的升高硬度先下降后上升,当温度为670℃时,钢材平均HBW硬度值最低(HBW238左右),回火组织为均匀的回火珠光体组织。     

高温不锈轴承钢Cr14Mo4的热处理、组织和性能

试验研究了电渣重熔Cr14M950～1 200 ℃淬火、450～550 ℃回火后钢的组织和性能.结果表明,(890±20)℃退火后钢的HB硬度值207～255;1 100～1 120 ℃淬火500～525 ℃四次回火后钢的组织由细针状回火马氏体、残余奥氏体和碳化物组成,HRC硬度值61,断裂韧性KIC为31.5～32.1 MPa·m1/2;Cr14Mo4钢200 ℃高温接触疲劳寿命L10为1.1×105,并且Cr14Mo4钢具有较好的耐磨性能.     

高强韧U20Mn2SiCrNiMo贝氏体钢轨热处理工艺的优化

研究正火-回火和等温热处理工艺对U20Mn2SiCrNiMo贝氏体钢轨显微组织和力学性能的影响。结果表明:试验钢经900℃正火+300℃回火后的力学性能为抗拉强度为1396MPa,伸长率为16.0%,冲击吸收功K_U2为57J,HB硬度值402;试验钢经870～930℃加热空冷至300℃等温处理后,抗拉强度基本保持在1300 MPa左右,伸长率为17.0%,冲击吸收功K_U2≥80 J,HB硬度值375～395;和传统的正火+回火工艺相比,优化的等温热处理工艺可以大幅提高U20Mn2SiCrNiMo贝氏体钢轨的冲击韧性,室温冲击吸收功由57J提高到80J以上,提高40%～56%,而断后伸长率基本保持不变,抗拉强度和踏面硬度略有降低。最佳优化工艺为:870℃正火后空冷至300℃保温4h后空冷。     

回火温度对中碳合金钢4Cr5MoSiV1Nb组织和性能的影响

 为了优化合金性能，研究了回火温度对中碳合金钢4Cr5MoSiV1Nb组织和性能的影响。试验结果表明，4Cr5MoSiV1Nb合金钢的二次硬化温度区间为300～550 ℃，峰值出现在550 ℃，此时硬度值为56.3HRC，同时伴有冲击韧性的显著降低，冲击韧性降低的原因是合金钢回火时含铬铬的细短棒状合金渗碳体在晶界析出，可以推测减少淬火合金钢中铬的偏析将会减少晶界析出，提高冲击韧性。微量铌的加入形成了（V，Nb）C强化相颗粒。合金在250～350 ℃回火综合性能最佳，可以达到冲击韧性15 J/cm2、硬度55HRC以上。     

组织状态对X120管线钢力学性能的影响

在实验室条件下对热轧X120管线钢进行两种不同工艺淬火,研究了回火温度对不同淬火态试验钢组织力学性能的影响。试验结果表明:直接快冷工艺下,显微组织以板条铁素体+马氏体为主;缓冷+直接快冷工艺下以粒状贝氏体+板条铁素体+马氏体为主。随回火温度升高,两种试验钢强度均出现起伏,在400~500℃范围内回火后,冲击功和伸长率均得到改善;采用直接快冷工艺在350℃和600℃回火后出现断口分离现象,从而导致力学性能波动,而缓冷+快冷工艺在回火过程中力学性能稳定性较好。因此,采用缓冷+快冷工艺+(450~500℃)回火,其力学性能达到X120级管线钢性能要求。     

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.