Gd对ZL205A合金显微组织和力学性能的影响

研究了不同质量分数Gd对ZL205A合金铸态及T6态显微组织和力学性能的影响.采用光学显微镜、荧光光谱仪和电子探针对制备的试样微观组织和元素分布进行分析,并利用电子拉伸试验机对铸锭的力学性能进行测试.结果表明:微量稀土元素Gd能细化ZL205A合金的晶粒,并与合金中的其他元素形成新相,能提高合金铸态和T6后的力学性能;当Gd加入量为0.06％时,综合力学性能最优,铸态时抗拉强度为192MPa,伸长率为11.1％;T6态时抗拉强度达到421.1MPa,伸长率为10.2％.但当Gd添加量过多时,合金的组织与性能均产生恶化.     

热处理对Mg-Sm变形镁合金组织与性能的影响

采用拉伸、硬度、显微组织观察等方法,研究了热处理对挤压态Mg-Sm合金组织和力学性能的影响.结果表明,实验合金经T5处理后的硬度高于T6处理的,热处理后弥散析出的强化相提高了Mg-Sm合金的力学性能,尤其是提高了屈服强度.Mg-Sm合金T5处理峰时效时的σ<,b>达到217.4 MPa,σ0.2达到162.1 MPa,δ为13.1%.     

热处理对挤压变形Mg-12Gd-3Y-0.6Zr合金力学性能及显微组织的影响

采用硬度检测、拉伸力学性能测试、金相、扫描及透射电镜观察等方法,研究了挤压态Mg-12Gd-3Y-0.6Zr合金经T4、T5和T6热处理后显微组织及力学性能的变化.结果表明:挤压态合金宜采用T5热处理.经T5热处理后,合金的屈服强度、抗拉强度分别达到372、403 MPa,远高于T4、T6处理的,其原因在于T5热处理后合金中存在大量棱镜片状第二相.T6热处理时,虽然合金的时效强化效果优于T5态合金,但晶粒长大严重降低了合金的力学性能.     

Mg-RE(Ce,Nd,Y)-Zn-Zr合金显微组织及力学性能研究

通过光学显微镜、扫描电镜及X射线衍射对Mg-RE(Ce，Nd，Y)-Zn-Zr合金显微组织和力学性能进行了分析研究，揭示了实验合金在不同稀土元素作用下的结构特点及断裂行为。实验合金在挤压和T2(T6)热处理后的拉伸力学性能分别为251．3MPa，275．5MPa和253．3MPa。高温力学性能1^#合金在150C拉伸时强度为196．4MPa，2^#、3^#合金在250C拉伸时强度分别为187，3MPa和219．6MPa。     

热处理对Mg-5Gd-0.5Sc-Mn合金组织与力学性能的影响

利用光学显微镜、扫描电镜及力学性能测试等分析手段研究了不同热处理条件对Mg-5Gd-0.5Sc-Mn合金的微观组织和力学性能的影响.结果表明,Mg-5Gd-0.5Sc-Mn合金具有良好的室温性能及高温稳定性.比较T5和T6两种热处理工艺发现:挤压态合金在200 ℃经过不同时间的时效,T5态较T6态的峰值时效硬度高,且T5态到达峰值时效的时间比T6态的短;合金T5态的室温抗拉强度可以达到216MPa,200 ℃达到191 MPa,均高于T6态的191和186MPa;T5态室温及高温条件下的断裂模式表现为准解理及微孔聚集的塑性断裂,而T6态室温及高温条件下分别为解理和准解理的脆性断裂.     

时效处理对高锌7075铝合金力学性能的影响

通过力学性能指标对比及断口组织扫描,研究了不同时效工艺对高锌7075合金力学性能的影响。结果表明:与T6处理相比,合金在回归工艺处理后硬度峰值为216. 2 HV,提高不足4%; T6+再时效期间,合金随保温时间的延长抗拉强度迅速下降,伸长率增长缓慢,在20 h时合金抗拉强度峰值为556 MPa,伸长率最高只有4. 2%;回归时效处理(RRA)后的合金综合力学性能优良,最佳RRA工艺为120℃×24 h+220℃×10 min+160℃×20 h,其抗拉强度达到588 MPa,伸长率可达10. 3%。     

RE及时效工艺对Al-Mg-Si合金组织和性能的影响

研究了铝合金中RE含量及热处理工艺对Al-Mg-Si合金板材的显微组织、力学性能的影响。研究表明,添加一定量的RE可以明显改善板材的力学性能,在T4P+烘烤状态下,RE含量为0.2%的合金具有最高的强度,屈服强度达到281MPa,比不含RE的合金高出约40MPa;抗拉强度达到373MPa。表明加入0.2%的RE后合金的强度和塑性都有很大的提高。对于RE含量为0.2%的合金,T4+烘烤条件下,虽然板材伸长率较高,但板材的屈服强度和抗拉强度分别较T6态低120MPa和40MPa;T4P+烘烤处理后,组织中出现了细密的析出相,抗拉强度非常接近于T6态,伸长率较T6态提高了4%,表明预时效处理后更能发挥RE对合金性能的有益作用。     

Zr、Cr元素对Al-Si合金电导率与力学性能的影响

通过正交试验和验证试验研究了不同的Si、Zr、Cr元素含量对Al-Si合金电导率与力学性能的影响.结果表明:当合金的成分为5%Si、0.35%Zr、0.35%Cr、1%Cu、0.5%Mg,经过T6处理后,电导率达到25.35 MS/m,抗拉强度达到361 MPa,伸长率达到2.83%,布氏硬度为109.34,均超越ZL101A.合金中的Si在改善合金力学性能的同时直接减少Al基体的有效导电截面,使合金的电导率下降;微量Zr可以在几乎不影响电导率的情况下提高合金力学性能;Cr元素对合金起到一定的强化作用.通过试验可将Al-Si合金的电导率提高5%～8%.     

热处理对Mg-Gd-Y变形镁合金组织与力学性能的影响

制备了3种不同成分的Mg-Gd-Y三元合金,并对其显微组织和力学性能进行了研究.结果表明,Mg-6Gd-(2-4)Y三元合金的铸态组织由α-Mg和呈现典型的网状共晶形貌的Mg24(GdY)5相组成,其体积分数随Y含量的增加而增大.热挤压过程中Mg24(GdY)s相破碎,呈颗粒状沿挤压方向排列.挤压态合金在高温固溶处理后,大部分Mg24(GdY)5相溶入基体.挤压态合金在固溶+时效(T6)处理和直接时效(T5)处理过程中都形成了β沉淀.3种合金中Mg-6Gd-4Y合金在T5态的性能最好,强度高达350 MPa.     

热处理对挤压态Mg-5Sn-2Si-2Sr合金组织及性能的影响北大核心CSCD

为了确定挤压态Mg-5Sn-2Si-2Sr合金合适的热处理方案,分别采用硬度计、X射线衍射仪、力学性能试验机、光学显微镜,研究了该合金经T4(固溶处理)、T5(200℃×12 h时效)和T6(固溶+时效)热处理后显微组织及力学性能的变化。结果表明:挤压态Mg-5Sn-2Si-2Sr合金宜采用T5热处理工艺。经T5热处理后,在晶界处析出大量Mg2Si强化相,使合金的屈服强度、抗拉强度分别达210.9 MPa、257.0 MPa,高于挤压态、T4和T6热处理工艺下的合金强度。T4热处理时,固溶强化作用远小于退火软化作用,致使合金力学性能的下降。T6热处理时,析出相及晶粒尺寸的长大使得合金力学性能的提高受到了限制。     

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.