45号钢,不锈钢,铝合金的电镀妆

叙述了用电镀技术连接４５号钢管、不锈钢管、铝合金管的实验研究工作，用拉伸试验测定了这三种材料的镀接强度。研究表明，基体材料的表面处理，镀接材料与电解液的选取对连接强度有着明显的影响、待镀坡口的角度为１０５－１３５°时，可以得到最 连接强工。     

45号钢、不锈钢、铝合金的电镀连接

叙述了用电镀技术连接45号钢管、不锈钢管、铝合金管的实验研究工作。用拉伸试验测定了这三种材料的镀接强度。研究表明,基体材料的表面处理、镀接材料与电解液的选取对连接强度有着明显的影响。待镀坡口的角度为105～135°时,可以得到最佳的连接强度。     

管式结晶器电镀设备及其电镀工艺

本发明提供了一种方坯连铸机用的管式结晶器铜管内壁电镀设备和利用这种设备对管式结晶器进行电镀的工艺。该电镀设备包括镀液贮槽、过滤装置及相关的控制装置和连接管路，其电镀槽由作为电镀阴极的管式结晶器铜管、夹具密封盖、阳极钛篮组成，电镀工艺是将结晶器内表面脱油处理后，用含有氨基磺酸钴、钨酸钠、氯化氢、硼酸、十二烷基硫酸钠、     

铍焊接技术研究发展概况

铍及铍合金在航空航天、电子工业和国防工业等方面应用十分广泛.结合铍的焊接性,论述了当前国内外铍的焊接技术概况,针对钎焊、熔化焊、扩散焊等焊接工艺,介绍了一些比较成功的铍的焊接工艺以及部分连接工艺,同时分析了铍焊接中存在的缺陷问题.     

双功能带缝剪力墙连接链的试验研究

连接链是双功能带缝剪力墙的关键控制元件，本文根据13个钢筋混凝土连接链的受剪试验，对其受力性能和受力阶段进行了研究，分析了影响连接链主要受力性能的参数，根据试验结果和理论分析，提出了连接链开裂、屈服和受剪姑载力特征点的有关计算公式。     

TN-4高导电耐温弹性合金——优良的代铍铜材料

高导电耐温弹性合金(TN-4)系上海交通大学,上海合金厂和杭州电连接器厂共同研制的新型弹性材料,它具有与铍青铜相媲美的优良的导电性和高弹性模量,相当高的强度,良好的延展性和加工性,而抗应力松弛性能却大大优于铍铜,可以承受200℃高温(铍铜最高只能用于150℃)并具有良好的电镀、焊接,抗腐蚀等性能,且生产过程无毒,热处理范围比铍铜宽,价格远低于铍铜,故是一种理想的耐高温导电弹性材料,也可作为优良的代铍铜材料。     

陶瓷材料电场辅助连接技术研究现状及发展趋势

陶瓷材料因具有良好的机械性能、抗腐蚀性、耐高温性及抗氧化性等,被广泛应用于航空航天、医疗、能源交通等领域,陶瓷材料自身及其与金属材料的连接技术对于实际工程应用具有重要意义。由于部分陶瓷材料与电场的特殊作用机理,将外加电场应用于陶瓷材料的连接技术中,可以获得多种普通连接技术所不具备的优势,如连接温度较低和连接时间较短等,这就催生了新型陶瓷材料电场辅助连接技术。本文着重梳理了陶瓷及陶瓷基复合材料电场辅助连接技术的研究现状,对近年来电场辅助连接技术的研究进展进行了综述,重点介绍了电场辅助扩散连接(Electric field-assisted diffusion bonding, FDB)技术、放电等离子体烧结(Spark plasma sintering, SPS)连接技术以及新型低温快速闪连接(Flash joining, FJ)技术的连接机理、典型界面微观结构、接头强度及影响因素等,阐述了不同电场辅助连接技术的适用范围和局限性,并对陶瓷材料电场辅助连接技术的发展进行了展望。     

单螺栓连接梁的非线性连接层建模与参数识别

针对线性的螺栓连接层等效模型无法表征进入微观滑移状态后结合部动力学行为的问题，用Voce本构关系对线性连接层等效模型做出了改进，使其能表征螺栓结合部的非线性动力学行为。以单螺栓连接梁为研究对象，试验探究了不同预紧扭矩对其固有频率的影响，测试了其在不同幅值谐波激励力下的频响函数。通过遗传算法对连接层等效模型的四个非线性参数进行了识别，分别包括初始屈服应力、切线模量和两个形状参数，识别了参数后模型频响函数计算值与试验值的误差在10%以内，表明改进后模型的准确性与可行性。改进后连接层等效模型可以用于装配结构非线性行为的预测。     

双功能带缝剪力墙连接键的试验研究

连接键是双功能带缝剪力墙的关键控制元件。本文根据13个钢筋混凝土连接键的受剪试验,对其受力性能和受力阶段进行了研究,分析了影响连接键主要受力性能的参数。根据试验结果和理论分析,提出了连接键开裂、屈服和受剪承载力特征点的有关计算公式。     

特高压输电线路连接金具的高强度材料选型

该文通过对现有连接金具材料以及特高压输电工程连接金具发展趋势的分析,提出了特高压输电工程线路连接金具的材料选型需满足高强度化、防腐性能好、低温性能优良、经济性好等要求,通过对比分析及试验验证提出几种高强度连接金具材料,以期满足特高压输电线路工程连接金具的轻型化要求,从而降低施工难度,节省成本,提高线路建设水平,为特高压输电线路高强度材料的连接金具选型提供参考。     

铍青铜零件电镀银工艺的改进

从分析铍青铜材料的特殊性入手,针对性地采取有效的前处理工艺措施,以硫代硫酸盐镀银取代传统的有毒的氰化镀银,分析了银镀层变色的原因并提出了相应的抗变色处理措施.     

A Distribution-Free Bayesian Approach for Determining the Joint Probability of Failure of Materials Subject to Multiple Proof Loads

Survival of manufacturing materials or component parts may depend on two or more variables, and yet joint strength tests can be difficult to perform. For many such materials, multiple strength properties can be estimated only using destructive testing. This problem gives rise to a technique called proof loading—stressing units up to a prescribed load, destroying only the weaker units, and leaving the survivors for further tests. We propose a distribution-free Bayesian approach for estimating the probability of joint failure under two proof loads. Our method does not assume that proof-load survivors are undamaged.     

Avoiding crack nucleation and propagation during upset bulging of tubes

As an alternative to joining by fusion welding, joining by upset bulging (JUB) can be applied in cases where tubes are joined to plates, sheet metal, or other tubes and profiles. If a tube is joined to a pierced flat plate, joining is accomplished by creating bulges in the tube by axial compression, which enclose and securely lock the plate. The JUB process has a large potential for reducing cycle times, realizing joints between different materials and for increasing the dimensional accuracy of the joints compared to fusion welding. The joints produced by this forming technique are free from the negative impact of heat affected zones on the material properties. However, the material undergoes large plastic deformation during the JUB process. When the bulges are fully compressed, local damage and failure can be observed which reduce the service life properties of the joints. This paper presents an experimental and numerical study of the damage evolution and crack initiation in mechanical joining by upset bulging. Experiments were carried out to analyse the occurrence of failure. The results are supported by FE analyses. Nucleation of cracks strongly depends on the final bulge height and consequently on the degree of deformation on the inner side of bulges. Tensile tests show that cracks in the bulge reduce the strength of the joint to half of the undamaged material. A new bulge design with a modified shape is presented, which reduces the damaging effect of the upset bulging process and thus improves the strength of the joints.     

Improvements of mechanical properties in dissimilar joints of HDPE and ABS via carbon nanotubes during friction stir welding process

Thermoplastic materials can be joined via friction stir welding (FSW), but the traditional tools fail to get excellent quality. The aim of this work is to investigate the effect of the multiwalled carbon nanotubes (MWCNTs) on the morphology and mechanical property of the dissimilar joints of high density polyethylene (HDPE) and acrylonitrile butadiene styrene (ABS) during submerged friction stir welding (SFSW). Different amounts of MWCNTs were added to the interface of the joint. The results show that the number of defects, such as pores and crack, could be decreased by adding the MWCNTs. The tensile and hardness tests were carried out as the mechanical properties of the weld samples, and the results showed that adding the MWCNTs to the joint increased the tensile strength and elongation, but decreased the hardness of the joint. The volume of the groove is used to fill the MWCNTs, however, it is easy to form cracks in the joint when it was too large.     

Spot welding of metal laminated composites

Composite materials of steel sheets joined by interlayers of zinc or lead- tin, show very good impact and corrosion resistance properties. Resistance spot-weld characteristics of these composite materials made of steel sheets and non-ferrous metals have been tested. Spot welds of composites with both zinc and lead- tin interlayers present good behaviour in peeling tests. Shear tests of the welds also show very high strength, probably as a consequence of simultaneous brazing because of the alloyed layer of non-ferrous material around the weld spot. This good welding behaviour enhances the possibilities of application of this composite.     

Influence of the thermomechanical processing on the fracture mechanisms of high strength aluminium/pure aluminium multilayer laminate materials

The microstructure and mechanical properties, with emphasis in the impact fracture toughness behaviour, of two multilayer laminate materials have been investigated. The multilayer materials are constituted by alternated sheets of pure aluminium (Al 1200 or Al 1050) and high strength Al 7075 alloy. Stacked layers of these alloys have been successfully joined using two processing routes with different total hot rolling strains. Both laminates have been tested at room temperature under impact Charpy tests, three-point bend tests and shear tests on the interfaces. Both laminates exhibited more than eight times improvement in impact fracture toughness over the monolithic Al 7075-T6. The toughness increase in the higher rolling strained laminate is almost entirely due to crack blunting mechanism, while in the lower strained laminate, crack deflection by delamination and crack renucleation processes were active.     

Predictive distribution of strength under control

The joint distribution of strength of materials is derived in terms of a set of conditional distributions to be used in studies on structural reliability. Bayes theorem of probability theory is used to update prior distributions for the parameters of Gaussian sequences by direct observations and/or by compliance tests. Maximum-Likelihood estimators are given for the efficient quantification of prior information. The formulae are applied to concrete production judged by standard tests. It is shown that statistical uncertainties must not be ignored in structural reliability studies.     

多层316L不锈钢板真空扩散连接研究

实现了150层316L不锈钢板的真空扩散连接,通过拉伸测试和金相观察,得到了接头力学性能和界面组织特征。结果表明,高温退火后母材的屈服强度和拉伸强度明显下降,断后伸长率显著提高。相较于高温退火后母材的力学性能,垂直试样的屈服强度高,但拉伸强度和断后伸长率低;平行试样屈服强度高,拉伸强度与母材相当,断后伸长率低。室温和高温垂直/水平拉伸试样均呈现出典型塑性断裂特征。接头顶部、中部和底部等各区域扩散连接质量良好,界面组织特征相似。      

Evaluation of the tensile and fatigue behaviour of ingot metallurgy beryllium/aluminium alloys

The tensile and fatigue behaviour of ingot metallurgy beryllium/aluminium alloys produced by Nuclear Metals, Inc., is determined as a function of temperature. The wrought alloy and the casting alloy are both shown to have a very high stiffness to density ratio compared with common structural materials. The wrought alloy was found to have superior fatigue strength, tensile strength and ductility relative to the casting alloy; it also maintained a greater fraction of its tensile strength as a function of temperature. The stiffness of the materials can be readily explained using standard composite theory, where the material is treated as a discontinuous beryllium-reinforced aluminium matrix composite. The strength of the casting alloy is controlled to a large extent by the strength of its aluminium alloy matrix. In contrast, strengthening increments from both dislocation-based mechanisms and load transfer appear to be operative for the wrought material. Fractographic analysis of tensile specimens showed that preferential failure of the aluminium regions or the beryllium/aluminium interfacial regions occurs under certain circumstances. Fracture analysis of fatigue samples revealed no obvious fracture initiation sites and no evidence of limited/controlled crack growth regions. This revised version was published online in November 2006 with corrections to the Cover Date.     

Reinforced direct bonding of optical materials by femtosecond laser welding

A process for reinforcing a direct bond between optical materials using femtosecond laser welding is presented. As a side benefit, the optical transmission properties of the joined components are shown not to be altered by the joining process. The joints exhibits higher shear breakage loads, yielding a maximum measured joint strength of 5.25 MPa for an applied load of 75 kg in fused silica. The laser sealing of direct bonds between dissimilar materials improves their resistance to thermal shocks. Direct bonds sealed by a circular weld seam can withstand thermal shocks at temperatures at least twice as great as nonreinforced direct bonds. The combination of ultrashort laser welding and direct bonding provides an innovative joining method that benefits from the advantages of both contributing physical processes.