平针搅拌头调修对铝合金焊接接头组织与性能的影响

通过拉伸、弯曲和硬度等试验以及金相显微组织分析,系统研究平针搅拌头不同调修次数下的6082-T6铝合金焊接接头组织与性能。试验结果表明:所有拉伸试件的断裂位置均位于热影响区,抗拉强度满足试验要求;弯曲性能较好;焊接接头有较为明显的软化现象;焊接接头各个区域的显微组织随调修次数的增加均无明显变化。     

热调修对6082-T6铝合金焊接接头组织与力学性能的影响

通过拉伸、弯曲和硬度等试验以及显微组织分析,研究了不同调修温度和不同调修次数对6082-T6铝合金焊接接头组织与性能的影响。结果表明:在低温(240~260℃)下进行1~3次和在中温(280~300℃)下进行1次焊后热调修时接头强度满足要求,所有拉伸试样均在热影响区处断裂;接头均有软化现象产生,且相同调修温度下2次和3次调修时接头软化现象更加严重。调修次数增加时,各区域晶粒变得粗大,析出相数量增加。     

调修次数对铝合金焊接接头力学性能及微观组织的影响

采用火焰对铝合金焊接接头进行调修矫正是轨道车辆制造工厂普遍采用的工艺手段。A5083-H111,A6061-T6,A7075-T651等3种铝合金材料是轨道车辆制造的主要结构材料,不可避免地存在焊接残余应力及残余变形,因此需要大量地进行火焰调修以确保尺寸精度和残余应力的消除。以轨道车辆常用的A5083-H111,A6061-T6,A7075-T651铝合金焊接接头为研究对象,采用温度为200℃火焰对3种铝合金焊接接头进行多次调修,研究不同调修次数对铝合金焊接接头微观组织及力学性能的影响。研究结果表明:不同调修次数对A5083-T111铝合金焊接接头的各项拉伸性能及疲劳性能均无明显影响。不同调修次数对A6061-T6铝合金对接接头拉伸及疲劳性能均有显著的影响。随着调修温度的上升和调修次数的增加,A6061-T6铝合金对接接头拉伸及疲劳性能均呈一定幅度的下降。不同工艺条件下热影响区组织差异较大,热影响区晶粒的长大导致了焊接接头性能的下降。随着调修次数的增加,A7075-T651铝合金对接接头的抗拉强度和屈服强度下降均很明显,但伸长率几乎没任何变化,同时疲劳性能随着调修温度的上升和调修次数的增加而下降。     

隧道型缺陷对6082-T6铝合金FSW焊接接头力学性能和疲劳性能的影响

采用单轴肩搅拌摩擦焊对6082-T6铝合金型材进行焊接,通过拉伸、弯曲、硬度、疲劳试验和金相分析等,对6082-T6铝合金焊接接头的组织、力学性能和疲劳性能进行分析研究。结果表明：0.1 mm隧道型缺陷接头的拉伸性能和弯曲性能优于4.4 mm隧道型缺陷接头的;从硬度测试结果来看,不同隧道尺寸对焊接接头的硬度影响较小,但热影响区均有软化现象;疲劳试验显示,在相同应力水平,4.4 mm的隧道型缺陷接头的疲劳性能较差;依据金相来确定2种隧道型缺陷的尺寸。     

前预热对厚板6082铝合金焊接接头性能的影响

采用不同的预热温度,通过拉伸、弯曲等试验及金相组织分析,对厚板6082铝合金焊接接头的组织和性能注行研究.结果表明:预热温度越低,接头的抗拉强度越高,但均低于母材抗拉强度；预热温度越高,热影响区软化现象越明显；当预热温度达到一定值时,焊接接头产生液化裂纹.     

预热温度对6082铝合金焊接接头的组织和性能影响

选取受电弓结构主要材质之一的6082-T6铝合金为研究对象,采取不同的预热温度对6082-T6进行TIG焊接,并对焊接接头的组织和力学性能进行了对比分析.结果表明:预热温度为100℃时,焊接接头的强度系数为0.61;预热温度越高,接头显微组织的晶粒越粗大,接头强度损失越严重;过高的预热温度使得接头热影响区的软化现象较严重,增大了热影响区的宽度.     

焊丝成分对6082-T6铝合金焊接接头组织和性能的影响

采用ER5356和ER5087焊丝对12 mm厚6082-T6铝合金进行熔化极惰性气体保护焊(MIG)后,通过显微硬度测试、拉伸力学性能测试、光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM)等研究焊丝成分对焊接接头力学性能与显微组织的影响。结果表明:采用ER5087焊丝焊接的6082-T6铝合金焊接接头焊缝区晶粒更细小;抗拉强度、屈服强度、断后伸长率以及焊接系数均高于ER5356焊丝焊接的6082-T6铝合金焊接接头的;两种焊丝焊接的6082-T6铝合金焊接接头的硬度最低区域与拉伸断裂位置均在距离焊缝中心10~15 mm处的热影响区,该区域β″强化相聚集长大、粗化,导致析出相强化作用减弱,成为焊接接头性能最薄弱区域。     

6082铝合金MIG焊焊接接头组织与力学性能研究

通过拉伸、弯曲、硬度试验以及金相分析等对6082铝合金MIG焊接头的力学性能与显微组织进行了研究。结果表明:采用5087焊丝焊接6082铝合金时,具有较好的抗拉性能,板厚8和4mm的焊接接头焊态的抗拉强度分别为母材的77.8%和73%;弯曲断裂集中在熔合线处,弯曲角度均较小;6082铝合金MIG焊接头焊缝中心组织为等轴晶,靠熔合线的焊缝晶粒沿散热方向呈柱状晶,熔合区晶粒粗大;软化区出现过时效效应,使Mg2Si长大,成为接头最薄弱的区域。     

焊接热输入对6082铝合金焊接接头组织性能的影响

6082铝合金薄板焊接接头热影响区存在明显的软化现象,拉伸试验时试样的断裂位置多数在热影响区,焊接接头常因抗拉强度不足而导致焊接工艺评定试验失败。通过严格控制焊前工艺准备,采用TIG焊接工艺,研究了不同焊接电流和焊接速度下焊接热输入对6082铝合金焊接接头组织和性能的影响。发现对于厚度为3 mm的6082铝合金试板,焊接热输入控制在0.291～0.334 kJ/mm时,焊接接头的抗拉强度可满足要求。     

不同焊丝对6082铝合金焊接接头组织性能的影响

采用ER5356和ER5087铝合金焊丝对6082-T6铝合金板材进行焊接,研究了不同焊丝对6082-T6铝合金力学性能和显微组织影响。结果表明,ER5087焊丝焊接的焊缝硬度高于ER5356焊丝的焊缝硬度,这是由于ER5087焊丝中的Zr细化焊缝晶粒的结果。拉伸试验时焊接接头均断裂于热影响区,ER5087焊丝焊接的接头比ER5356焊丝焊接的接头平均屈服强度和抗拉强度高,断后伸长率稍好。     

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

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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.