金属板件压接数值模拟及模具设计

以有限元分析软件ANSYS为平台,基于弹塑性有限元理论建立压接模具和板件的有限元模型,对金属板件压接过程中的应力场和应变场进行计算。通过模拟结果与试验结果的比较,证实了采用ANSYS数值模拟对压接模具进行优化设计的可行性,同时研究了影响连接强度的模具设计参数。     

陶瓷及陶瓷基复合材料连接的研究进展

综述了近年来陶瓷及陶瓷基复合材料连接的研究进展。包括陶瓷及陶瓷基复合材料润湿机理的研究、润湿性的改善、连接界面组织结构的演变及与接头力学性能的关系、接头连接机理及连接应力的缓解方法。同时,对连接中间层的选择,包括玻璃陶瓷中间层、复合中间层、复合钎料及梯度中间层的研究也进行了归纳总结。分析了目前研究已经取得的突破进展及仍然存在的问题,并对未来陶瓷及陶瓷基复合材料连接的研究方向进行了展望。     

电磁铆接试样质量分析

采用试验方法,通过电磁铆接和气动铆接方式,对铆接试样从铆钉宏观变形和微观连接方面进行质量对比分析。结果表明,与气动铆接相比,电磁铆接能一次成形,铆接试样钉杆变形均匀,波动度小,铆接质量稳定,不易出现钉头被铆歪、开裂等现象。在铆钉成形钉头与铝合金板连接处,电磁铆接铆钉变形较气动铆接剧烈。在铆钉钉杆与铝合金板连接处,电磁铆接试样铆钉与铝合金板连接的紧密程度要好于气动铆接。在铆钉钉杆与复合材料连接处,电磁铆接铆钉对复合材料的挤压程度要小于气动铆接,未出现复合材料分层和开裂。     

Effect of anodizing on direct joining properties of aluminium alloy and plastic sheets by friction lap joining

We have proposed a novel joining process, friction lap joining (FLJ), to join metallic material sheet directly to polymer sheet and have investigated mechanical and metallurgical properties of these dissimilar joints. The joining mechanism is discussed with an evaluation of the TEM microstructure at the joint interface between A2017 aluminium alloy and two kinds of polymer, ethylene-acrylic acid copolymer (EAA), and high density polyethylene (PE). EAA sheet was easily joined to an as-received aluminium alloy sheet by FLJ, because EAA had a polar functional group, COOH. On the contrary, PE was not able to be joined to an as-received aluminium alloy, because PE had no polar functional group. However, anodizing of aluminium alloy was effective to join these materials by the assistance of the anchor effect.     

变电极力对管板单面电阻点焊质量的影响

根据管板单面电阻点焊结构特点,建立了采用伺服焊枪的管板单面电阻点焊试验系统.针对管板焊接过程中变形大、形成环形熔核质量不可靠等问题,提出了基于改变焊接过程中电极力来提高焊点质量的方法,并研究变电极力对管板焊焊点强度及焊接变形影响的规律.结果表明,通电阶段熔核生成初期减小电极力,可明显提高焊点拉剪强度,减小焊接变形;冷却阶段减小电极力对焊点质量也有所提高,但影响较小.研究结果对管板焊接工艺参数的制定及单面电阻点焊在车身焊装中广泛安全的应用具有重要意义.     

Joining process and strength in PVC friction stir spot welding with fabricating composite material at welding area*

In order to improve the strength of FSSWed PVC joints, SiC particles were compounded into the welded region at the same time as the welding process. The joining process and its effect on strength of FSSWed PVC joints were investigated in a joining experiment with a PVC plate having a different guide hole diameter for filling the SiC particles. In the case of the specimen compounded with SiC particles with guide hole diameter of 8 mm, SiC particles could be dispersed uniformly in the welded area. In the specimens with guide hole diameters of 5 and 2 mm, dispersion of SiC particles was not observed inside of the welded area. Degradation and increase in local mechanical property was significantly observed at edge of the keyhole and inside the welded area, respectively, in the specimen with a guide hole diameter of 8 mm. The width of welded area increased with increasing guide hole diameter. The joining strength was improved by fabricating composite material in the welded region. The strength increased with increasing guide hole diameter. It is considered that joining strength was significantly affected by the width of the welded area. According to temperature distribution and observation of material flow using a high speed camera, contact between the welding tool and SiC particles before plunging into a lower sheet induced increasing heat input during the process and resulted in promoting the friction stirring. Therefore, it is considered that change in guide hole diameter leads to change in contact area between welding tool and SiC particles and also change in width of the welding area resulting in change in the joining strength.     

Effect of rotating speed on rotating tool spot joining of 5052 alloy

ABSTRACT

Rotating tool spot joining in low rotating speed range is investigated in this study. Torque of the motor increased with the decrease in rotating speed of the motor. Joint strength increased significantly with the decrease in rotating speed. Shoulder plug fracture was observed as a characteristic fracture mode under the long joining time and low rotating speed joining conditions and it obtained the large plastic deformation. The rotational motion of the joining interface was similar with the Rankin vortex. The relationship between the joining interface deformation by the external force and the plastic deformability by the friction heat on this joining process was considered from the experimental results.     

Microstructure of heavily deformed magnesium-lithium composites containing steel fibers

The microstructure of deformation-processed metal-metal composites (DMMC) of Mg-Li alloys containing steel reinforcing fibers was characterized to correlate the fiber size to the deformation strain and mechanical properties of the composite material. Micrographs taken using scanning and transmission electron microscopy techniques revealed fiber sizes larger than predicted from the deformation applied to the bulk composite. Deformation strain in the fibers, therefore, was less than in the bulk material. Measurements from SEM and TEM micrographs were used to calculate the actual deformation strain present in the fibers. This strain was then used to adjust rule-of-mixture (ROM) predictions of the strength of the composite material. However, the experimental strengths of these materials were still less than the adjusted ROM values, potentially due to the presence of fibers considerably larger than the average size measured stereologically. Of the many models used to describe the strengthening observed in DMMC materials, the Hall-Petch relationship best describes the experimental data. Details of the strengthening models are discussed in relation to these composite materials.     

复合电热餐具铝/不锈钢接触反应钎焊新技术

采用接触反应钎焊实现了复合电热餐具铝热管与铝板以及铝板与不锈钢板结构的高致密连接. 通过选择接触反应钎焊的中间层成分, 采用Si为中间层介质进行钎焊工艺试验. 对接头组织的显微分析表明, Si中间层介质与铝基体之间发生共晶反应所产生的Al-Si共晶液相, 能够将铝加热管与铝板以及铝板与不锈钢板大面积结构致密地连接在一起.     

厚大螺母与镀锌薄钢板环凸焊接头组织与性能

通过大量试验,探讨了厚大螺母与镀锌薄板环凸焊接头的组织与性能,结果表明：当接头具有良好的性能时,结合面存在的微区熔化并凝固的细小等轴晶,其接头的连接机制属于微区熔化和固态塑性变形＋动态再结晶的混合连接模式。     

Hybrid joining process for carbon fiber reinforced thermosetting plastic and metallic thin sheets by chemical bonding and plastic deformation

A new joining process for thin metallic and continuous carbon fiber reinforced thermosetting plastic (CFRP) sheets is proposed. This joining process is a hybrid of chemical bonding and plastic deformation, usable for ultra-lightweight structures. In contrast to conventional joining methods, such as rivet joining with an adhesive, the proposed method does not require any additional components and can eliminate holes that would cut the continuous carbon fibers and cause stress concentration. Hence, a smaller weight and a higher joining quality can be attained, especially for thin sheets. Aiming at making comparison and demonstrating the applicability of the proposed hybrid joining method, two thermosetting CFRP sheets with different laminates were used as lap adherends in the experiment. The effects of the deformation temperature, the use of a dummy sheet and the relative positions of the sample and dummy sheet on the joining quality were systematically investigated and optimized. The optimal hybrid joint shows high-quality bonding without delamination or adhesive failure. The tensile shear test of single-lap A2017P-CFRP hybrid joints manufactured under optimal experimental conditions indicates that, compared with adhesive bonding and conventional rivet joining with an adhesive, the proposed joining method has obvious superiority in terms of tensile shear load, slip displacement and absorption energy.     

铝/钢异质金属搅拌摩擦焊技术研究进展

铝/钢异质金属复合结构具有轻质节能、降低成本、可以满足不同的工作条件等特点,在航空航天、船舶制造等领域的应用日益受到重视。由于铝和钢的物理化学性质存在巨大差异,铝和钢的连接成为焊接领域的难点问题。搅拌摩擦焊作为一种固相连接方法,具有热输入低、高温停留时间短、焊接变形小等特点,对克服铝/钢异质金属性能差异带来的焊接困难具有优势,已成为铝/钢异质金属焊接的研究热点。综述了铝/钢异质金属搅拌摩擦焊国内外研究现状,主要涉及搅拌头材料选择与结构设计、焊缝成形、焊接工艺窗口、力学性能、接头冶金结合、连接机制以及外源辅助搅拌摩擦焊新技术,可以为铝/钢异质金属结构的轻量化设计提供新思路,最后对其发展趋势进行了展望。     

半固态技术在材料连接和复合材料制备中的应用

半固态材料技术在材料成形加工领域得到了广泛的应用.综述了国内外将半固态技术作为材料连接与复合材料制备技术的研究及相关的专利,重点分析了半固态连接技术的优点并与传统工艺进行了比较,展望了这种新技术在材料科学与成形加工工程领域中的应用前景与研究方向.     

Laser direct joining between stainless steel and polyethylene terephthalate plastic and reliability evaluation of joints

Metals and plastics have been widely used in industrial applications, and joining of a metal to a plastic is necessary and important from a manufacturing viewpoint. Therefore, we have developed laser-assisted metal and plastic (LAMP) joining as an innovative rapid laser direct joining without adhesives or glues. In this research, the joining between a Type 304 stainless steel plate of 3 mm thickness and a polyethylene terephthalate (PET) plastic sheet of 2 mm thickness was exploited at several travelling speeds with a diode laser beam of line profile at 170 W power. The joints of 30 mm in width possessed extremely strong tensile shear loads of approximately 3000 N at the maximum. Transmission electron microscope photographs of the joints demonstrated that Type 304 and PET were bonded together on the atomic or molecular level through a Cr oxide film of stainless steel. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry analysis indicated the possibility of chemical bonding between hydrocarbon and metal through oxygen. Concerning reliability evaluation for the LAMP joints, some joints could have high shear tensile loads of approximately 3000 N even after heat cycle test and show superior air-tightness in helium leak test. Consequently, it was confirmed that the LAMP joining of SUS304 and PET plates could produce a sound joint of high strength, nanostructural binding through the oxide film and fundamental reliability for practical use.     

Fabrication of Mo–Cu composites by a diffusion-rolling procedure

A plastic deformation approach to Mo matrix composites remains a longstanding challenge in the processing of refractory metal. Toward this objective, we explored a selective fabrication of the diffusion-rolling procedure. With diffusion bonding initially, a primary sandwich sheet was achieved. The interfacial strength of Mo/Cu was enhanced by the plastic deformation after rolling. Ultrathin Cu–Mo–Cu sheet and Mo–Cu alloy sheet with Cu matrix containing distributed uniformly fibrous Mo were fabricated. HR-TEM analysis revealed that atomic-level interdiffusion of Mo and Cu was present at the interface. Therefore, it is concluded that the diffusion-rolling procedure can be potentially employed as a joining method for the fabrication of Mo–Cu composites.     

C/C复合材料与镍基高温合金连接接头的力学性能和微观结构

采用Ni、Si粉末作中间层连接材料,利用真空热压工艺成功制备C/C复合材料与镍基高温合金(GH3128)的连接样件。并借助X射线衍射仪、扫描电子显微镜和材料万能试验机,研究连接温度对其连接接头力学性能和微观结构的影响规律。结果表明,随着连接温度的升高,不仅接头中间层的元素分布更加均匀,而且接头的剪切强度也随之明显增大。当连接温度为1160℃时,连接接头的剪切强度可达12.6MPa。     

The influence of deformation conditions in solid-state aluminium welding processes on the resulting weld strength

Solid bonding of aluminium is an important joining technology with applications in fabrication, forming and new low-carbon recycling routes. The influence of deformation conditions on the strength of the resulting weld has yet to be fully assessed, preventing optimization of current processes and development of new ones.     

JOINING OF Ni_3Al BY PRESSURIZED COMBUSTION SYNTHESIS USING GLEEBLE 1500 TEST SIMULATOR

1.Orderedintermetalliccompoundsandintermetallic--Inatrixcompositeshaveemergedasanewclassofadvancedmaterialsforstmctundapplications.AInongthesecompounds,nickelaldrinideNi,hi,whichhastheLI,--typeofferedcrystalstructurebelowitsmeltingpoint(1395t),isanattractivematerialforuseatelevatedtemperatures['J.UnfortUnately,theweldabilityOftheseintermetalliccomPOundsbyconventionalfusionweldingp~essesisgenerallyverylicitedbecauseoftheirhighsusceptibilitytohotcrackingbothintheheat--affectedzoneandinthefus…     

微波焊接进展

阐述了微波焊接过程中微波和物质作用的机理、陶瓷的升温特征、实验装置的优化以及近年来国内外微波焊接陶瓷的发展状况, 分析了焊接过程中存在的问题, 并对微波焊接作出了展望.     

3A21铝合金-20钢管磁脉冲连接实验研究

利用低电感线圈磁脉冲连接(MPJ)装置, 研究了放电电压、管件径向间隙和搭接区长度对3A21铝合金-20钢管连接接头拉伸和剥离力学性能的影响. 通过SEM进行了接头界面的微观形貌观察和元素分布的EDS分析. 结果表明, 随放电电压提高, MPJ性质由机械连接向冶金连接转变. 在放电电压为5.5 kV、径向间隙为1.5 mm、搭接区为3/4线圈长度条件下, 获得界面呈小波纹状、Al和Fe元素发生互扩散的冶金接头. 与接头界面临近的基体金属发生了剧烈 塑性变形和晶粒细化.