双脉冲MIG焊对5052铝合金焊接接头力学性能的影响

研究了双脉冲和单脉冲MIG焊对5052Al-Mg合金焊接接头力学性能的影响.结果表明,在合适的双脉冲MIG焊工艺参数下,获得了美观的鱼鳞纹焊缝表面,焊缝金属为大量细小的等轴晶组织,接头力学性能得到提高.相比于单脉冲焊获得的接头,双脉冲焊接接头的焊接系数更高,达到93.3%,焊缝区硬度值得到提高,接头冲击韧性也更优.此外...     

脉冲MIG焊对7N01铝合金焊接接头组织及力学性能的影响

采用金相、硬度、拉伸和微型剪切试验研究了7N01S-T5铝合金单脉冲MIG焊、双脉冲MIG焊和超微弧焊三种焊接工艺条件下焊接接头的组织及力学性能.结果表明,焊接热影响区晶粒长大,且析出强化相出现在晶界处;双脉冲MIG焊焊接接头系数高于单脉冲焊和超微弧焊,超微弧焊接接头韧性优于单脉冲和双脉冲焊接接头.     

不同MIG焊方法对7N01-T4铝合金焊接接头力学性能的影响

采用硬度、拉伸和微型剪切试验研究了轨道列车用7N01-T4铝合金在单脉冲MIG焊、双脉冲MIG焊和超威弧MIG焊三种焊接工艺条件下焊接接头的力学性能。结果表明:双脉冲MIG焊焊接接头系数要高于单脉冲焊和超威弧焊;双脉冲焊和超威弧焊比单脉冲焊的热影响区宽度要窄;超威弧焊接接头的韧性和塑性均要优于双脉冲接头和单脉冲接头。超威弧MIG焊接方法可以改善铝合金焊接接头整体性能。     

不同MIG焊方法对6082铝合金焊接接头力学性能的影响

采用硬度、拉伸和微型剪切试验研究了A6082铝合金在单脉冲MIG焊、双脉冲MIG焊2种焊接工艺条件下焊接接头的力学性能。结果表明:双脉冲MIG焊方法获得的铝合金接头焊接系数达到了70.0%,单脉冲焊获得的接头焊接系数达到了68.6%。单脉冲及双脉冲MIG焊焊接接头硬度都是热影响区处的最低,拉断部位均在热影响区的软化区域,剪切试验结果也证明热影响区部位剪切功最低。另外,双脉冲焊接接头的冲击韧性优于单脉冲焊接头的。     

6082-T6铝合金CMT+P焊与双脉冲MIG焊的接头组织及性能对比分析

对3 mm厚6082-T6铝合金型材采用冷金属过渡+脉冲焊(CMT+P)和双脉冲熔化极气体保护焊(MIG)两种焊接工艺进行了对接接头焊接试验,并对这两种工艺获得的焊接接头的力学性能和微观组织进行了评价。结果表明:采用CMT+P焊接工艺获得的焊接接头的强度优于双脉冲MIG焊接接头的强度; CMT+P焊焊缝软化现象较双脉冲MIG焊有明显改善; CMT+P焊焊缝熔合区比双脉冲MIG焊的焊缝熔合区窄,焊缝区晶粒更细小均匀,在双脉冲MIG焊缝热影响区产生晶间液化裂纹。采用CMT+P焊可以获得更优良的6082-T6铝合金型材焊接接头。     

双丝脉冲MIG焊的双脉冲焊接方法

为优化双丝脉冲MIG焊的焊缝成形质量,提出双丝脉冲MIG焊的双脉冲焊接方法,构建基于DSP的双丝脉冲MIG焊的双脉冲数字化交替相位协同控制系统,对双丝脉冲MIG焊的单脉冲和双脉冲焊接进行平板堆焊试验.结果表明,双丝脉冲MIG焊双脉冲焊接系统实现了稳定的双脉冲焊接过程,焊缝成形良好.对单脉冲和双脉冲焊接所得焊缝的横截面宏观金相对比分析结果表明,双脉冲对焊接熔池有很强的搅拌作用,双脉冲焊接所得焊缝晶粒比单脉冲焊缝晶粒更小,说明双脉冲具有细化晶粒的效果,证明在双丝脉冲MIG焊中应用双脉冲有一定的优化作用.     

轨道车辆用6082铝合金双丝脉冲MIG焊焊接工艺

通过对6082铝合金采用双丝脉冲MIG焊的焊接方法进行了工艺试验.分析了6082铝合金双丝脉冲MIG焊的特点,提出了合理的双丝脉冲MIG焊焊接工艺,进行了焊缝质量检验,分析了焊接接头的显微组织并测试其力学性能.结果表明:焊接工艺参数合理.在焊接接头中未发现任何焊接缺陷,焊缝质量良好;焊接接头强度、塑性均可达到母材的60...     

直流双脉冲MIG焊对5A06铝合金焊缝组织和性能的影响

针对5A06铝合金薄板采用传统TIG和MIG焊接工艺时出现焊接效率低、接头性能难以满足使用要求的问题,采用直流双脉冲MIG焊对5A06铝合金平板试样进行焊接试验。利用拉伸试验机、扫描电子显微镜和光学显微镜等实验设备研究直流双脉冲MIG焊工艺对5A06铝合金焊接接头微观组织和力学性能的影响。结果表明:当送丝速度为5 m/min、焊接速度为50 cm/min,脉冲频率为3 Hz、气体流量为25 L/min、焊丝干伸长为12 mm时,获得了美观的鱼鳞纹焊缝表面,焊缝区为大量细小的等轴晶组织,而且焊缝横截面气孔较少。焊接接头具有较好的抗拉性能,焊接强度系数达到90%以上。     

高速列车6005A-T6铝合金型材激光-双丝MIG复合焊

分别利用双丝MIG焊和激光-双丝MIG复合焊进行了高速列车6005A-T6铝合金型材的焊接试验研究,对比分析了两种焊接方法的焊缝成形、焊接变形、接头力学性能及其接头微观组织.结果表明,激光-双丝MIG复合焊接6005A-T6铝合金型材时的焊接速度可达4.5 m/min,焊接过程具有较好的搭桥能力,对接间隙达到1.4 mm时,仍可以获得良好的焊缝成形.当焊接速度大于或等于4 m/min时,复合焊接头的焊接变形量仅为常规双丝MIG焊的40%左右,其抗拉强度达到了母材强度的83%,比常规双丝MIG焊接头的抗拉强度提高了9%左右.     

高强Al—Cu合金双丝MIG焊工艺研究

研究了单丝脉冲MIG焊、低速和高速双丝脉冲MIG焊对高强Al-Cu合金焊缝组织及性能的影响.实验结果表明:低速双丝脉冲MIG焊焊缝组织以粗大的等轴枝晶为主,α(Al)-CuAl2共晶呈长条网状分布,降低了焊缝的强度、硬度和塑性;高速双丝脉冲MIG焊焊缝组织为细小的等轴枝晶,接头性能和单丝脉冲MIG焊相近,但高速双丝脉冲MIG焊焊接效率远高于单丝脉冲MIG,因此特别适合于厚板铝合金焊接.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

正~~     

Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.