镁合金的冲压模具设计研究

本文以AZ31B镁合金手机外壳的冲压模具设计和在普通机械式锻压机床上的冲压生产为例，对AZ31B镁合金冲压成形过程中的板材制备、冲压模具设计、模具及板材的温度、冲压变形速度、润滑剂的选用等关键技术做了较为隶统的实验研究。实验表明．通过合理地选取模具参数并对拉深速度、坯料及模具温度等主要影响因素的控制，可有效地解决AZ31B镁合金拉深生产过程中的拉裂缺陷。在普通机械式锻压机床上能成功地冲压生产出镁合金手机外壳。     

AZ31镁合金薄板手机外壳温冲模具设计及成形性能研究

设计并制造了AZ31镁合金薄板的手机外壳温冲模具,并对其成形性能进行试验研究。试验表明,eta/DYNAFORM有限元模拟软件能够较好的验证模具设计的合理性和分析AZ31镁合金薄板冲压成形性能,通过合理地选取模具参数,并对拉伸速度、润滑条件、坯料以及凸、凹模温度等主要影响因素的控制,可有效地解决AZ31镁合金拉伸生产过程中的拉裂缺陷,在普通液压机上能成功冲压出镁合金壳形件。     

镁合金手机外壳冲模设计及实验研究

以AZ31B镁合金手机外壳冲模设计和在普通机械式锻压机上的冲压生产为例,对AZ31B镁合金冲压成形过程中的板料制备、冲模设计、模具及板料的温度、冲压变形速度、润滑剂的选用等关键技术作了较为系统的实验研究。实验表明,通过合理地选取模具参数并对拉伸速度、坯料及模具温度等主要影响因素的控制,可有效地解决AZ31B镁合金拉伸生产过程中的拉裂缺陷,在普通机械式锻压机上能成功地冲压出镁合金手机外壳。     

AZ31B薄板手机外壳温冲试验研究

通过对AZ31B镁合金手机壳的温冲试验研究,分析了凸、凹模温度、镁板温度和加热时间、冲压速度以及润滑条件对成形结果的影响.试验表明,在保证坯料充分退火和模具结构合理的前提下,拉深凸模温度保持在230 ℃,凹模及压边圈温度保持在280～320 ℃,用石墨对坯料凸缘和压边圈、凹模肩部进行有效润滑,同时,施加合适的压边力作用,便可以成功地冲压出镁合金壳形件.     

AZ80镁合金切屑回用的探讨

试验探讨了利用热压．热挤压变形工艺，对AZ80镁合金切屑挤压成棒料再回用，制定了棒料的成型工艺。在压制坯料时，切屑温度为330℃，模具温度为350℃，压力为200MPa。挤压时，坯料温度及模具温度与压制坯料一致。挤压比为25：1，挤压速度为20mm／s。回用棒料经过（200oc＋8h）热处理后，σb为310MPa、σs为230MPa、δ为7％。探讨了AZ80镁合金切屑在热挤压变形成形后的微观组织和力学性能。     

汽车前防撞梁热成形冷却过程温度场数值模拟

采用ProCAST软件,对高强钢板热冲压成形工艺冷却(淬火)过程进行数值模拟分析,计算了连续多个冲压工作循环下模具和坯料的温度场。结果表明,模具在连续多个冲压工作循环中,温度呈周期性的快速上升和快速下降的变化趋势,当每一个冲压工作循环结束时,模具的温度都保持在50℃左右。坯料在淬火过程中,其温度呈快速降低趋势,冲压结束时坯料的出模温度分布在75℃²25℃上下,出模温度随冲压工作循环的进行而依次略有升高,并达到稳定。对模具和坯料进行试验测试,其温度值与数值模拟值吻合较好,说明该计算模型和方法对成形工艺设计有较好的预测评价作用。     

双辊连续铸轧镁合金板材的冲压加工特性

对镁合金连续铸轧薄板冲压零件进行了初步研究.在板坯性能合适的条件下,通过控制工艺环节和工艺参数包括下料温度、预热和加工温度、模具设计、润滑和预热等,发现双辊连续铸轧镁合金板材具有细晶粒和变形组织对变形加工有利.在模具适当预热的情况下,对于低合金化的镁合金薄板不加热,某些类型的零件挤压和冲压也能进行.     

复合形变对AZ31镁合金微观组织及力学性能的影响

对AZ31镁合金板材进行复合形变工艺研究,对比了不同坯料温度、下压量和模具温度对镁合金板材微观组织和力学性能的影响。结果表明,坯料温度为275℃、下压量为29%,模具温度为150℃时,复合形变后镁合金板材拥有理想的微观组织和力学性能。此时镁合金板材平均晶粒尺寸为7.84μm,显微硬度(HV)为91.99,屈服强度为212 MPa,抗拉强度为298 MPa,伸长率为17.2%。     

AZ31镁合金复杂形状壳体拉深成形试验研究

通过拉深成形试验研究了AZ31镁合金复杂形状壳体的成形性能,分析了成形温度、拉深速度、坯料加热时间及润滑等工艺参数对镁合金手枪壳体拉深成形件质量的影响规律.结果表明,合理的成形工艺参数:成形温度为290～350 ℃,拉深速度为0.1～0.2 mm/s,加热时间为5～10 min,润滑剂采用二硫化钼和机油的混合物,成功地加工出合格的复杂形状的镁合金手枪壳体.     

锻压工艺对汽车镁合金棒材性能的影响

采用不同的坯料加热温度、模具温度和锻比对汽车用AZ80镁合金棒材进行了锻造,并进行了不同温度下的力学性能测试与分析。结果表明,随坯料加热温度从440℃提高至480℃或锻比从5增大至9,棒材的抗拉强度、屈服强度和断后伸长率均先增大后减小;随模具温度从320℃提高至360℃,棒材的抗拉强度和屈服强度均先增大后减小,断后伸长率先增大后基本不变。坯料加热温度优选为470℃、模具温度优选为350℃、锻比优选为8。     

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.     

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.     

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.     

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.