外加电磁场辅助焊接技术的研究现状

外加电磁场辅助焊接是近年来新兴的技术手段,以非接触的方式作用于焊接过程,可以通过电磁力影响熔池流动、电弧形态及熔滴过渡行为等方式提高焊缝性能及生产效率、改善焊缝成形及组织结晶。分析总结了国内外学者利用不同类型外加电磁场对熔池流场、焊接电弧和熔滴过渡的影响,其中主要包括外加横向磁场、外加纵向磁场、外加尖角磁场等;但是由于外加电磁作用下电弧熔积成形的物理过程极其复杂,焊接过程中热、力和电磁等物理场作用机理尚未分析透彻,深入的理论和数值研究成为迫切需要。     

电沉积工艺对铁—镍—磷合金磁参量影响的研究

本文通过对电沉积铁-镍-磷合金磁性能的的测定,探讨了不同电沉积工艺参数及施加磁场电沉积对合金主要技术磁参量(μ_0、H_c、B_r、Ph及Bs)的影响规律;并获得具有较佳磁性能的电沉积工艺参数。研究结果表明,随pH值的增大,非晶合金的B_s增大,H_c、B_r、Ph等呈下降趋势。随D_k的增大,非晶合金的B_s不断增大,μ_o持续下降,H_c、B_r、Ph等呈上升趋势。当pH=1.5、D_k=10A/dm~2左右时,非晶合金具有较佳的软磁特性。外加磁场电沉积可有效的调整铁-镍-磷合金的磁性能。     

电、磁场对金属凝固组织的影响及应用

利用外加物理场凝固细晶技术是目前材料加工领域的研究热点。综述了各种电、磁场对金属凝固组织的影响，并对其主要的机理进行了探讨；并对电、磁场在金属凝固成形中的应用和进一步研究进行了展望。     

外加磁场对铁磁材料电火花小孔加工的影响

针对电火花加工中电蚀产物排出困难、加工效率低、电极损耗严重等问题,研究了外加磁场对铁磁性材料电火花小孔加工的影响,分析了铁磁性电蚀微粒在加工区域受外加磁场磁力作用的影响规律,实验研究了在不同电极材质条件下,外加磁场对加工速度、电极损耗的影响。结果表明:采用磁场电火花复合加工方法在铁磁材料工件上加工小孔,其加工速度和电极损耗都比普通电火花加工有明显改善。     

电、磁场对金属凝固组织的影响及其应用

利用外加物理场凝固细晶技术是目前材料加工领域的研究热点。综述了各种电、磁场对金属凝固组织的影响，对其主要的机理进行了探讨；并对电、磁场在金属凝固成形中的应用和进一步研究进行了展望。     

不锈钢带极电渣堆焊磁控制技术

利用外加磁场可以达到克服带极电渣堆焊时产生的咬边和成形不良的目的.在进行线圈式外加磁场和固定铁芯式自感磁场的两种形式的磁控装置研制及试验基础上,提出了合理的磁控装置结构及主要工艺参数;阐述了磁极位置、焊接材料、焊接规范对磁控效果的影响.     

强磁场对电沉积镍铁合金膜显微组织的影响

在电沉积镍铁合金膜过程中施加了不同强度的纵向强磁场,研究了磁场强度对电沉积镍铁合金膜的微观形貌、晶粒取向和成分的影响。结果表明:随着磁感应强度增加,镀层表面晶粒先粗化,然后细化为数百纳米的颗粒层;同时样品截面组织经历了由层状生长转为树枝晶、脊状晶和条状晶的一系列变化;在12 T强磁场下条状晶沿外磁场方向破碎为球状微晶组织;强磁场使样品(111)晶面择优取向,并进一步促进了Fe2 的优先沉积,使样品中铁含量随外加磁场强度的增大而增加,而膜的饱和磁化强度也线性提高。     

外加磁场对镁合金焊接接头疲劳性能的影响

在镁合金TIG焊焊接过程中引入外加纵向磁场,通过对其焊接接头的疲劳试验、断口分析和显微组织观测,研究了外加磁场对焊接接头疲劳寿命的影响规律及作用机理.结果表明,外加磁场与电弧、溶池中的导电粒子相互作用产生电磁搅拌,改变焊接熔池液态金属结晶过程中的传热和传质过程,从而改变晶粒的结晶方向,细化一次组织,球化净化杂质,减少偏析,提高接头的力学性能和疲劳性能.外加磁场状态下焊接接头的疲劳寿命高于无磁场下的疲劳寿命,达到母材的90%.     

马氏体不锈钢不同剩余磁场条件下短时干摩擦的摩擦损伤行为研究

本文研究了马氏体不锈钢磨削加工产生的剩余磁场对其短时干摩擦过程中摩擦系数的影响.结果表明:剩余磁场对摩擦行为的影响与外加载荷有关,当外加载荷较低时,摩擦系数随剩余磁场强度的升高无明显变化;随外加载荷的升高,剩余磁场强度对摩擦系数的影响作用增大;当外加载荷较高时,摩擦系数随剩余磁场强度的升高而增大;在短时摩擦过程中,随着剩余磁场强度的升高,摩擦界面吸附磨损颗粒的能力增强,加速了摩擦界面的磨粒磨损,使摩擦系数升高.     

磁场下镁合金A-TIG接头成形性及显微组织分析

在对5 mm厚的AZ31B镁合金板材进行A-TIG焊焊接过程中引入外加纵向磁场,试验所用的活性剂是以氧化物为基的活性剂,试验中改变磁场参数,对焊接接头的成形性、组织及性能进行试验和检测,研究磁场参数对镁合金A-TIG焊过程的影响规律.结果表明,活性剂及磁场共同作用可以改善焊接接头的成形性和组织形态,在磁场频率为10 Hz,磁场电流为2 A时,焊接接头的成形系数和性能得到了最佳值,此时成形系数为2.304,硬度为980.98 MPa;外加磁场通过电磁搅拌作用与活性剂相结合,改变了熔池的流行形态,使金属液由四周向中心流动并伴有搅拌,进而使焊缝熔深增大的同时细化组织,改善接头力学性能.     

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.     

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.     

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.     

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.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.