激光填丝焊接铝锂合金T型接头的组织和力学性能

以铝锂合金2A97(底板)/2099(筋板)T型接头为研究对象,采用ER5356铝镁焊丝进行激光填丝焊接,分析了焊接接头的显微组织和力学性能。结果表明:接头的平均抗拉强度为425 MPa,达到2A97-T3母材抗拉强度的93%。T型接头首先在焊趾起裂,然后沿熔合线扩展,最终断在底板,呈穿晶断裂的特征。焊缝区硬度值在70~90 HV之间,比母材硬度低。焊缝区域晶粒形态主要有细等轴晶、柱状晶和等轴晶,其中细等轴晶主要在在熔合区靠近焊缝侧形成;焊缝中心等轴晶区的第二相粒子分别在晶间和晶内出现,并伴随明显的铜偏析现象。     

铝锂合金T型接头双侧激光同步焊接组织合金调控研究

针对2060/2099铝锂合金机身壁板T型接头双侧激光同步焊接组织的改善及力学性能的提高,采用焊缝合金化手段对焊缝组织进行合金调控,研究了合金元素对焊缝热裂纹敏感性及力学性能的影响。结果表明,2060/2099铝锂合金双侧激光同步焊接组织内存在特殊的等轴细晶区,为接头薄弱区域;焊缝晶界主要由AlLiSi和Al_6CuLi_3两种晶间相及Al-Cu,Al-Si共晶组织构成;采用Al-Si-Cu系新焊丝CW3能够促进Al_6CuLi_3相及二次枝晶的形成,有效提高晶界强度并抑制热裂纹的产生,等轴细晶区内显微硬度水平的提高使T型接头的综合力学性能得到明显改善,其纵向抗压载荷提高为92.7 kN,横向抗拉强度提高为412 MPa,达到母材抗拉强度的80%以上。     

焊丝成分对2519铝合金焊缝组织与性能的影响

采用ER4047焊丝及ER2319焊丝对2519铝合金进行熔化极惰性气体保护焊(MIG),并对焊接接头的力学性能和焊缝组织进行了分析.结果表明,用ER2319焊丝焊接的焊接接头的力学性能优于ER4047焊丝;ER2319焊丝细化了焊缝区的组织;2519铝合金焊接接头的抗拉强度低于母材,焊缝处是焊接接头的最薄弱环节,其次是焊接热影响区内的软化区,θ'相粒子受热影响而粗化是形成软化区的主要原因.     

激光增材制造GH3625高温合金激光焊接头组织及力学性能

对激光增材制造GH3625高温合金进行激光对接焊实验,分析了焊接接头的显微组织演变规律和力学性能。结果表明,在热影响区,仅在上层晶界处析出大量Laves相,导致晶界发生明显粗化。沿焊缝上层至下层,熔合区和中间区由上层的胞状晶、柱状晶和等轴细晶逐渐转变为下层的柱状晶,且紧贴熔合线生长的等轴细晶的数量逐渐增多,中心区均为树枝晶。细小颗粒状γ′相弥散分布于焊缝;大量Laves相在中间区枝晶间析出,且形态由上层的条状逐渐转变为下层的颗粒状。接头抗拉强度为872MPa,达到母材抗拉强度的98.2%,伸长率达到母材的90.7%。接头断面近似呈45°斜面,断裂形式为脆性和韧性混合断裂方式。     

不同焊丝对喷射成形7055铝合金焊缝组织与力学性能的影响

对用喷射成形工艺制备的7055铝合金采用不同焊丝进行MIG焊焊接试验,对焊接接头组织和力学性能进行了研究。试验结果表明:ER4043焊丝焊接接头硬度为200 HV,接头抗拉强度为145 MPa,伸长率为2.23%;焊接接头主要以等轴晶为主,焊缝区为等轴晶和树枝状晶,熔合区和热影响区主要为等轴晶组织,断口为解理断裂。ER5356焊丝焊接接头硬度为90 HV,接头抗拉强度为190 MPa,伸长率为2.92%;焊接接头主要以柱状晶为主,焊缝区、熔合区主要为柱状晶组织,热影响区为粗大的等轴晶,断口为疲劳断裂形式。     

6005A铝合金MIG焊接接头组织及性能研究

采用MIG焊接技术对6005A铝合金进行焊接,研究了搭接接头与对接接头的力学性能、拉伸断口形貌,接头不同位置的微观组织及焊缝合金成分。研究表明,对接接头的抗拉强度达到母材的68%,搭接接头抗拉剪切强度达到母材的50%以上;两种接头焊缝组织均为细小的树枝晶与等轴晶,熔合线附近组织为粗大的柱状晶,对接接头断裂位置为接头热影响区,搭接接头断裂在焊缝处,接头断口存在韧窝与准解离面,断裂机制为韧脆混合断裂。母材中的强化相为Mg_2Si,焊缝中存在的强化相为Mg_5Al_8与Mg_2Si。     

时效时间对SP2215同种钢焊接接头微观组织和力学性能的影响

采用手工钨极氩弧焊(manual-gas tungsten arc welding, M-GTAW)和ERNiCr-3焊丝制备了SP2215小径管焊接接头，分析了650℃时效不同时间后接头的微观组织、力学性能及拉伸断裂机理.结果表明：焊态下SP2215母材组织由奥氏体和少量孪晶及一次NbN和Z相组成，焊缝金属以完全奥氏体组织凝固形成柱状晶，Nb元素在枝晶间偏析并形成呈链状分布的一次NbC相；时效50 h后SP2215母材奥氏体晶界处开始析出M₂₃C₆，并随时效时间延长逐渐粗化，同时焊缝枝晶间逐渐析出NbC相，并随时效时间延长逐渐形成团簇状；母材和焊缝显微硬度均随时效时间延长而升高，均在时效500 h时达到最大值且母材硬度始终高于焊缝硬度；不同时效时间接头室温拉伸时均以韧性方式在焊缝处断裂，但起裂位置和断裂方向随时效时间的延长发生改变，时效0～114 h时以横向拉断柱状晶的方式断裂，起裂位置为枝晶间一次NbC粒子，时效时间为500～2 012 h时以平行于柱状晶方向断裂，起裂位置为枝晶核心；650℃高温拉伸时接头断裂位置随时效时间延长逐渐从焊缝...     

不同焊丝对T6态Al-12.7Si-0.7Mg合金焊接接头组织性能的影响

采用ER4047,ER5183和ER5356 3种焊丝对厚度为6 mm的T6态Al-12.7Si-0.7Mg合金进行平板对接试验,使用双脉冲MIG单面双道焊缝成形工艺,确定了3种焊丝对应的焊接工艺参数并且获得了良好的焊缝成形。在此基础之上,对焊接接头进行金相组织观察和力学性能测试。结果表明,使用ER4047焊丝的焊缝接头组织与ER5183和ER5356接头组织有明显差别;3种接头的拉伸试验具有不同的断裂模式,采用ER5183焊丝的接头强度最高,约为母材的70%;显微硬度结果表明,T6态的母材受焊接热输入的影响后,热影响区内存在软化现象。     

合金元素对5083铝合金焊接工艺性的影响分析

采用合金元素含量不同的三种ER5183焊丝作为填充金属,对5083铝合金进行了焊接试验,并对焊接接头进行了无损检测、显微组织分析、拉伸性能测试。试验结果表明:焊缝区组织比母材区致密,晶粒细小、均匀,随着Mg含量增加,β(Al_3Mg_2)相析出增加,焊缝的抗拉强度增大;焊缝的抗拉强度达到母材的85%以上。     

析出相演变对2060-T8铝合金搅拌摩擦焊接头腐蚀行为的影响（英文）

采用搅拌摩擦焊对2060-T8铝合金板材进行焊接,研究析出相演变对接头显微组织和腐蚀行为的影响。在采用扫描电镜和透射电镜表征2060-T8铝合金搅拌摩擦焊接头上表面析出相演变行为的基础上,通过电化学试验和交变盐雾腐蚀试验研究接头各区域的腐蚀行为。研究表明,腐蚀行为与各区析出相的特性密切相关,由于θ′(Al_2Cu)相、T1(Al_2CuLi)相和δ′(Al_3Li)相的回溶,以及晶界相和无沉淀析出带的出现,轴肩影响区是腐蚀最敏感的区域;因为不存在晶界析出相,相比轴肩影响区,热机械影响区的抗腐蚀性能略有提高;热影响区和母材的抗腐蚀性能最好。     

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.     

Bulletin of the Awards in 2013

<正>Five reviewers and 9 published articles are selected as the Excellent Rewewerand Excellent Article in 2013 respectively.Excellent Reviewers:Prof.Z ongyi Ma(Institute of Metal Research,CAS,C hina);Prof.Y ongbo Xu(Institute of Metal Research,CAS,C hina);Prof.Guangping Zhang(Institute of Metal Research,C AS,C hina);Prof.Z hendui Cui(Tianjin University,China);