针状铁素体对超细晶铁素体钢力学性能的影响

针对利用形变强化铁素体相变工艺制备出的超细晶铁素体钢,其抗拉强度很高但伸长率偏低的问题,对其进行了组织精细分析。精细分析结果表明,针状铁素体的形成主要与轧后冷速有关,冷速越大,针状铁素体越多,针状铁素体对钢的力学性能具有双重影响,一方面钢的抗拉强度随着针状铁素体体积比的增加而增加;另一方面又因针状铁素体其内部的精细结构特征、形态特征、针尖效应及其尺寸等影响因素,使钢的伸长率大为降低。当将试验钢中针状铁素体体积比控制在7.28%左右时,可使钢的抗拉强度在高达740 MPa时,仍具有26%的理想伸长率。     

热轧E36钢中板埋弧焊接头的组织与力学性能

通过拉伸、冲击和金相检验等试验方法对热轧态E36钢12mm中板埋弧焊接头的力学性能与显微组织进行了研究。结果表明：采用H10Mn2焊丝＋SJ101烧结焊剂对E36钢中板进行焊接时,接头具有较高的抗拉强度和较好的低温冲击韧性;焊缝组织主要为针状铁素体、先共析铁素体和少量粒状贝氏体;热影响区组织主要为铁素体、珠光体和少量针状铁素体,针状铁素体是接头具有良好力学性能的主要原因。     

42CrMoA中针状铁素体组织的控制与力学性能研究

针对热轧态的42Cr MoA棒材中的针状铁素体组织,采用金相显微镜、扫描电镜、硬度计、拉伸机、冲击机检测样品的金相组织、力学性能,研究了调质前后的组织状态与综合力学性能的关系,并提出了控制方法。结果表明:热轧态时,针状铁素体组织的强度下降,伸长率上升,但冲击功降低;调质后,由等轴珠光体和铁素体得到的调质组织综合力学性能最佳,正火不能完全改善针状铁素体组织对后续热处理的不良影响。     

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 采用三点弯曲法研究了不同组织类型的X70级管线钢的硫化物应力腐蚀开裂(SSCC)行为。结果表明：均匀细小的针状铁素体为主的显微组织具有优良的抗SSCC性能;针状铁素体内高密度缠结的位错和碳氮化物在位错网络上的沉淀析出是针状铁素体钢具有优良的抗SSCC性能的主要原因。     

保护气体中氧气含量对低合金高强钢熔敷金属组织和力学性能的影响

使用不同氧气含量的保护气体对低合金高强钢HSLA-65进行了实心焊丝和药芯焊丝的熔化极气体保护焊。通过拉伸试验、冲击试验等力学性能检测,结合光学显微镜、扫描电镜、透射电镜和能谱分析等,研究了保护气体中氧气含量的变化对熔敷金属组织和力学性能的影响。结果表明:实心焊丝和药芯焊丝的熔敷金属显微组织均由针状铁素体和晶界铁素体组成。在相同保护气体成分下,药芯焊丝熔敷金属中针状铁素体比例大于实心焊丝熔敷金属,药芯焊丝熔敷金属的综合力学性能优于实心焊丝熔敷金属。随着保护气体中氧气比例的增加,实心焊丝熔敷金属中针状铁素体的含量先增加后减少;而药芯焊丝熔敷金属中针状铁素体含量一直在减少。两者熔敷金属的综合力学性能随针状铁素体比例的变化呈现出相同的变化规律。     

一些新发展的钢种

<正>IF钢-无间隙铁素体钢,铁素体内的碳含量很低,强度低,延展性好,具有非常好的冲压性能,广泛应用于汽车板的制造。AF钢-针状铁素体钢,指低合金高强度钢在连续冷却下获得的不同于铁素体加珠光体(F-P)的一种类贝氏体组织。它是以扩散和剪切的混合机制实现转变,因为相变只涉及到铁素体(F),其中的少量奥氏体只是     

低合金高强度钢焊缝针状铁素体联锁组织与性能

采用金属包埋切片微米-纳米表征法和电子背散射衍射技术分别研究了焊缝金属中针状铁素体形核夹杂和联锁组织特征。结果表明,由于Mn元素扩散到夹杂物内部使得周围形成贫Mn区,诱发针状铁素体在复合夹杂物上形核。同时针状铁素体还可以在已经形成的铁素体表面激发形核;铁素体生长过程中同原奥氏体保持固定取向关系;铁素体相互之间发生硬碰撞和交错现象;这些因素共同形成针状铁素体联锁组织。这种细小有效晶粒尺寸的针状铁素体联锁组织具有良好的强韧性匹配。     

低合金钢焊缝的针状铁素体微观组织

针对X70管线钢多道焊焊缝金属,利用Gleeble1500热模拟机进行了热模拟试验,对焊缝金属中初生针状铁素体组织及其与非金属夹杂物之间的关系以及经历二次热循环后感生形核的针状铁素体组织进行了SEM及TEM分析.结果表明,针状铁素体边界存在着一层富碳的薄膜,其长大既存在切变转变的特征,同时也伴随着C原子的扩散过程.共感生成的二次针状铁索体是在初生针状铁索体基体的高密度位错处形核并以一定的速度迅速长大到有限的尺寸.初生针状铁素体和共感形核针状铁素体都是在奥氏体晶内形核、长大,都具有细化奥氏体晶粒、提高多道焊焊缝金属和焊接热影响区韧性的作用.     

超细晶铁素体钢的力学性能及成形性能研究

采用形变强化铁素体相变超细晶轧制工艺,获得了750MPa级超细晶铁素体钢板,其超细晶铁素体体积比高达93%,晶粒尺寸仅为1μm,并具有优异的成形性能。对超细晶铁素体钢组织的精细分析发现,因铁素体晶界随晶粒超细化而减薄,使得其晶界对材料的力学性能具有双重影响,一方面,屈服强度随着晶界总长度的增加而提高;另一方面,又因晶界减薄而降低。研究表明,超细晶铁素体钢的组织性能关系虽然与霍尔-佩奇关系相吻合,但存在较大偏差,主要表现为斜率显著下降。文章对斜率下降的原因进行了机理分析。     

低合金高强度钢焊缝金属中针状铁素体的微观组织

利用光学显微镜,扫描电子显微镜及EBSD(electron backscattering diffraction)分析技术对800MPa级低碳微合金高强度钢的焊缝金属进行了分析.结果表明,焊缝金属组织主要为针状铁素体和贝氏体.针状铁素体以夹杂物为核心形核,该夹杂物主要是以Al2O3为核心形成的钛氧化物.针状铁素体以夹杂物为核心多维形核呈放射状生长,仅某些方向的针状铁素体晶核迅速长大,生长方向存在取向择优.EBSD分析同样表明针状铁素体晶粒存在取向择优.观察到由同一夹杂物生长,沿同一直线方向背向生长的针状铁素体取向相同,沿不同方向生长的针状铁素体取向不同,说明其沿原奥氏体惯习面生长,并非与夹杂物共格.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.