Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Internal Friction in Rail Waist of BNb and BNbRE Steels

The experi ments showed that the inclusions andpearlite of the steel were modified and/or refined ,andthe plasticity ,toughness , wearability as well as theservice life of the rail were obviouslyi mproved by add-ing RE.It was firstlyfoundthat as a result of additionof REinthe steel ,there appeared an obvious inhibit-ing and/or di minishing effect on the fatigue damage ,particularly on both nuclear damage and rail waistdamage[1 ,2]. However , whether the initiation and ex-tension of the residi…     

10PCuRE耐候钢耐蚀锈层的电化学特征

利用干湿周浸实验室加速腐蚀方法获得了不同稀土含量10PCuRE耐候钢和碳钢的腐蚀率,采用测定带锈试样阳极极化曲线、弱极化区线性极化曲线和交流阻抗谱的方法评价了耐候钢和碳钢生成锈层的性能,从电化学角度解释了钢样耐蚀能力的差别,并且得出稀土在一定的含量范围内可以减小腐蚀驱动力,促进锈层稳定致密化的结论。     

Application status and development prospect of rare earth in electrical steels

Rare earth(RE) plays a unique and irreplaceable important role in iron and steel.The developments in both basic research and application of RE steel are rapid in recent years.Especially, RE electrical steels attracts more and more attention.However, the relevant research is still in the exploration stage, and it is urgent to carry out systematic and in- depth research work. Based on the recent research results about the application of RE in electrical steels, the research status of RE in electrical steels under modern technical conditions and the effect mechanism of RE in electrical steels were summarized. The application of RE in conventional non- oriented electrical steels, grain- oriented electrical steels and Fe- 6. 5 mass% Si high- silicon electrical steels were discussed respectively. A large number of studies show that the addition of RE in electrical steels can significantly improve the magnetic properties, mechanical properties and texture of electrical steels.There is a broad application prospect of RE in the improvement of magnetic and mechanical properties for electrical steels, and the development of RE electrical steels with Chinese resources?? characteristics has an important academic value and a practical significance.     

非水溶剂电还原制取重稀土金属及合金的研究现状及发展

随着重稀土元素对铝、镁、铜、镍及钢铁等金属材料的功能化作用被广泛关注,使得作为战略性资源的重稀土元素在金属合金材料的应用领域拓展空间巨大.在此背景下,作为改性元素的重稀土金属及合金的市场需求必然猛增.由于重稀土单质自身的高熔点,混熔法、真空热还原法一直是生产制备重稀土金属及合金的主要方法,寻求一条低成本、高效、绿色的制备方法则至关重要.由于熔盐电化学还原法在生产低熔点轻稀土及合金工艺方面具有经济、高效等优势,近年来,通过熔盐电解方式直接制取低熔点的重稀土合金成为国内外学者研究的热点,从目前取得进展来看,具有广阔的发展前景.针对国内外重稀土金属及合金的熔盐电解法制取的研究现状进行了评述,从体系物理化学性质、电极过程机理、模拟计算等几个方面做了简要的总结和分析,以期对重稀土合金材料的制备研究提供有益的帮助.      

Pitting corrosion behavior of Cu-P-RE weathering steels

The weathering steels are prone to pitting corrosion in an environment containing chloride ions.The pitting behavior of Cu-P-RE weathering steels and its effect on the corrosion resistance of steels were investigated by multifarious analytical techniques,such as field emission-scanning electron microscopy(FE-SEM),electron probe microanalysis(EPMA),scanning Kelvin probe force microscopy(SKPFM),electrochemical workstation and a series of immersion tests.The results show that the original stripshap...     

Research on Thermal Wear of Cast Hot Forging Die Steel Modified by Rare Earths

Thermal wear of cast hot-forging die steel modified by rare earths（RE） was studied and compared with commercially used die steels. The function of RE and the mechanism of thermal wear of cast steel modified by RE were discussed. The results showed that with increasing content of RE, the wear rate of cast steel reduced at first and then increased. By adding 0.05% （mass fraction） RE, the cast hot-forging die steel with optimum thermal wear resistance was obtained, which was better than that of H13 and 3Cr2WSV. The large amount of coarse inclusions, （RE）2O2S, resulted from excessive RE, which obviously deteriorated thermal wear resistance. The mechanism of thermal wear of the modified cast die steel is oxidation wear and oxide fatigue delamination. The wear debris are lumps of Fe2O3 and Fe3O4.     

Kinetics of Formation of Large-Dimension Rare Earth Inclusion in Steels

The elemental distribution within the large-dimension rare earth inclusion in steels was studied through analysis on plane distribution of elements by EPMA (Electron Probe Microanalyzer). The kinetics and mechanism of formation of RE inclusion were discussed, taking 5CrNiMo steel with the addition of RE and other microalloying elements as example. RE inclusions nucleate on oxides and sulphides with high melting point and grow up separately, then integrated by relatively high surface activity, which is a particular characteristic of RE elements, in liquid phase and during the course of solidification. Finally, the fine and dispersed RE inclusions merge and grow into a large-dimension one.     

近年稀土钢研究进展与加速研发新思路

通过对近几年来稀土钢发展相关文献的调研,统计了稀土相关论文、专利增长数量和应用领域分布,分析了稀土钢的研发进展。结果表明,无论是基础研究还是应用领域拓展,稀土钢近年来都得到迅速发展,稀土电工钢和稀土TWIP钢成为最热门的研发钢种,但稀土添加工艺等关键技术的不足,以及有待发展的稀土钢研发方法,延缓了稀土钢的发展与应用。稀土钢生产实践表明各种稀土添加工艺中连铸结晶器喂线法是钢铁连铸生产最有效的稀土添加方法,稀土电渣重熔工艺对生产重大装备制造用大型铸件具有重要应用价值。介绍了有关引入材料基因组工程先进研究理念,发展高通量计算与模拟、高通量制备与表征研究方法,建立稀土钢数据库,加快稀土钢研发的新思路。     

高洁净轴承钢中稀土变质夹杂物行为分析

为了阐明稀土变质高洁净轴承钢中夹杂物的行为,进而优化轴承钢的稀土处理过程,通过向高洁净轴承钢中加入高纯稀土的方法,借助SEM、EDS和EPMA等观察和分析手段,重点对不同稀土含量轴承钢中夹杂物类型和析出行为进行表征和分析。研究结果表明,在不完全变质条件下,微量稀土能够优先变质钢中长条状MnS为RE₃S₄颗粒,RE₃S₄可在冶炼时独立析出或以Al₂O₃为核心析出,也能在凝固时与MnS以RE₃S₄·yMnS (y<1)复杂夹杂物的形式共同在Al₂O₃基底上形成。随着稀土含量的增加,在完全变质条件下,稀土元素与夹杂物的形成元素的结合序列依次为O、S、As、P和C,夹杂物类型演化序列为RE₂O₃、RE₂O₂S、RES、RE-S-As、RE-As(-P)/RE-O-As(-P)、RE-P-C/RE-O-P(-C)和RE-O-C。     

Effect of Rare Earth （Niobium） on Costed and Hot-Rolled Microstructure and Properties of Heavy Rail Steels

Effect of Rare Earth (Niobium) on Costed and Hot-Rolled Microstructure and Properties of Heavy Rail Steels     

稀土对碳素钢在模拟工业性大气腐蚀环境下耐蚀性的影响

 利用浸泡、电化学方法研究了Ce/La混和稀土对碳素钢在腐蚀介质中的缓蚀作用,采用相分析、周浸、锈层分析等方法研究了稀土对碳素钢耐工业性大气腐蚀性能的影响。结果表明：在模拟工业性大气腐蚀环境的酸性NaHSO3溶液中,稀土丝分解后生成的稀土离子是一种混合型缓蚀剂;在对碳素钢的缓蚀过程中,Ce/La离子沉积于同一区域;随钢中稀土含量增加,钢中相界固溶稀土和稀土/铁金属间化合物总量增加,钢的耐蚀性得到大幅度提高。另外,还对稀土减缓钢铁腐蚀过程进行了讨论,提出了稀土对碳素钢的缓蚀机理。     

海洋大气环境下低碳稀土钢耐腐蚀性能的研究

通过大气暴晒实验研究了海洋大气环境下低碳钢和稀土钢的腐蚀行为.结果表明,稀土元素有利于提高碳钢耐海洋大气的腐蚀性能.采用SEM、XRD以及电化学方法对腐蚀产物进行研究.发现稀土钢锈层组织缺陷较少,能有效阻挡腐蚀性离子侵入.稀土可以促进腐蚀产物中活性物相向α - FeOOH转化,并能细化锈颗粒,提高铁锈中非晶相比例.     

非金属夹杂物对不锈钢耐点蚀性能影响的综述

摘要：首先,总结了3种常用的非金属夹杂物对不锈钢耐点蚀性能影响的研究方法,即原位腐蚀观察、微区电化学法、原子力显微镜。其次,总结了硫化物、氧化物、稀土夹杂物3种不同类型夹杂物对不锈钢耐腐蚀性能影响。随着硫化物含量的增多,不锈钢的耐点蚀性能会下降;对于氧化物的影响,目前的研究集中在氧化物的成分对不锈钢耐点蚀性能的影响。不同成分的夹杂物对不锈钢耐点蚀性能的影响机制还不是很清楚;稀土夹杂物对不锈钢点蚀的影响主要与稀土对不锈钢中夹杂物改性有关。而后,汇总了目前提出的夹杂物对不锈钢耐点蚀性能影响的机制,即贫Cr区机制、微缝隙机制、活性机制。贫Cr区机制主要用于解释硫化物引起的点蚀,后2种主要用于解释氧化物引起的点蚀。最后,提出了夹杂物控制提升不锈钢耐点蚀性能的展望。     

Review of Studies on Rare Earth against Plant Disease

Agricultural application of rare earth (RE) has been generalized for several decades, and it is involved in crops, vegetables and stock raising in China. However, all the researches on RE mainly focus on the fields such as plant physiological activity, physiological and biochemical mechanism, sanitation toxicology and environmental security. Plant protection by using RE and the induced resistance of plant against diseases were summarized. The mechanism of rare earth against plant disease is highlighted, which includes following two aspects. First, RE elements can control some phytopathogen directly and reduce its virulence to host plant. Another possibility is that RE elements can affect host plant and induce the plant to produce some resistance to disease.     

稀土在汽车用先进高强钢中的研究现状

成分设计与优化是先进高强钢增强、增塑以及增韧的关键技术之一。随着钢质高纯化装备和技术的进步与发展,稀土元素在钢中的应用已由净化、夹杂物改性逐步向微合金化过渡。从第一代铁素体基软钢和高强低合金钢向第二代奥氏体基超高强钢,再到多相、亚稳和多尺度组织调控的第三代高强韧性钢,先进高强钢的微合金化技术一直是控制组织和性能的有效举措。稀土原子具备较大原子半径以及与O、S的高亲和力等优异特性,可从控制凝固与固态相变,影响碳元素与合金元素的扩散等多方面影响先进高强钢的组织结构,从而对其力学性能、成形性能以及耐腐蚀等服役性能产生显著影响。本文阐述了稀土元素分别在第一代、第二代和第三代典型先进高强钢中的作用机理,并展望了稀土元素在未来汽车钢中的应用前景。      

氟化稀土对异种钢焊接接头抗裂性能的影响

本文研究了用高合金焊条焊接带耐蚀喷焊层低碳钢时稀土对异种钢焊接接头抗裂性能的影响,结果表明：在焊条药皮中加入适量稀土可以提高接头的抗裂性能,但是加入量过多又会产生不良影响。适量稀土的加入能够改善焊缝组织,使异种钢焊接接头热影响区变窄、过热区晶粒长大受到抑制、过渡区脆硬层硬度显著降低,有利于异种钢焊接接头抗裂性能的提高。     

BNb与BNbRE钢轨踏面区的内耗

测量了BNb钢和BNbRE钢重轨踏面区使用(热轧)态及其700℃、30min WC、室温变形态试样的内耗。发现,两种钢轨热轧态试样都有Snoek—Kê—Kster(SKK)峰;但这两种钢热轧态样品的内耗,有较明显的差异:未加稀土的BNb钢轨的SKK峰明显地大于加丁稀土的BNbRE钢轨的峰,前者的峰温度也较后者高约20℃;但后者有可测的Snoek峰,而前者则没有此峰。两种钢变形态样品的SKK峰大致相同。对结果做了讨论。     

钙处理对稀土在C-Mn钢中作用的影响

 为了明确钙处理对稀土在C-Mn钢中作用的影响,利用扫描电镜、光学显微镜和超景深三维显微镜对热轧态试验钢夹杂物和显微组织进行了观测,结合热力学计算和冲击断口分析结果,对比研究了稀土和钙-稀土复合处理对C-Mn钢力学性能的影响规律。结果表明,稀土能将钢中典型夹杂物改性为近球形的含硅稀土氧化物的复合夹杂,尺寸细化,长宽比降低。钙-稀土处理后夹杂物变为球形含稀土和钙的复合夹杂,钢洁净度增高;添加钙能将稀土的收得率从7.6%提高到42.4%,有效提高稀土利用率,钙-稀土处理后珠光体所占面积百分比提高,钢的强度提高。证明采用钙处理提高稀土在C-Mn钢中的作用是可行的。     

稀土对铁基自熔合金喷焊层组织与耐蚀性能的影响

通过熔炼—雾化工艺制备了稀土铁基自熔合金粉末,并考察了稀土对铁基自熔合金喷焊层的显微组织及其在弱酸、中性盐溶液中耐蚀性能的影响。采用金相显微镜、SEM、EDAX对合金喷焊层的物相结构、显微组织进行了观察和分析。在实验结果的基础上,对稀土的有关作用机制进行了分析和讨论。