A review on ultrasonic spot welding of copper alloys

As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided.     

Effect of electropulse modification parameters on ingot macrostructure of Cu—Al—Ni shape memory alloys

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｋｎｏｗｎｔｈａｔｔｈｅｍａｉｎｏｂｓｔａｃｌｅｓｔｏｔｈｅａｐｐｌｉ ｃａｔｉｏｎｏｆｐｏｌｙｃｒｙｓｔａｌｌｉｎｅＣｕ Ａｌ Ｎｉａｌｌｏｙｓａｒｅｃｏａｒｓｅｉｎｇｒａｉｎ ｓｉｚｅａｎｄｉｔｓｃｏｎｃｏｍｉｔａｎｔｉ     

20#连铸矩形坯宏观组织缺陷及其遗传性

归纳和分析了铸坯宏观组织缺陷类型，生成机理，针对铸坯组织缺陷在管坯，钢管内外表面上的表现形式及其遗传规律进行了详细论述。     

《结构钢低倍组织缺陷评级图》(GB/T 1979-2001)解析

简要介绍了新修订的《结构钢低倍组织评级图》(GB/T 1979 2 0 0 1)国家标准。新标准主要对某些缺陷的名称、特征、产生原因及评定原则做了修改和补充 ,对个别缺陷的评级图片进行了修改 ,增加了三种缺陷 ,增加了小于 4 0mm和大于 2 5 0mm钢材的评级图 ,增加了“试样的截取及显示方法”和“检验报告”等内容     

Macroscopic and microscopic aspects of product formation in the Fe2O3-TiO2-Al disperse system burning in the SHS regime

The macromorphology and micromorphology of the combustion products of a Fe₂O₃-TiO₂-Al powder mixture burning in the regime of self-propagating high-temperature synthesis were studied. Significant differences were found in the structure of the products with variation in the ratio of the mixture components. A mechanism for shape and phase formation was proposed that allows the observed differences to be explained from unified positions. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 79–88, May–June, 2006.     

Determination of the mechanical properties of 15Kh1M1F steel after welding with high-concentration energy sources by the fractal parametrisation of the structure

The relationships governing the formation of the structure of metals in electron beam welding are investigated by fractal analysis, which determines the single numerical parameter for describing the macrostructures of welded joints in order to evaluate the homogeneity and fragmentation of the structure. The results are then used to determine the relationship of the welding conditions with the fractal dimension of the structure and the properties of the metal of the welded joint, in particular, the long-term strength limit.     

Mechanical Properties and Stability to Light Exposure for Dyed Egyptian Cotton Fabrics with Natural and Synthetic Dyes

Synthetic dyes are more available than natural dyes were in the past, because of lower prices and wider ranges of bright shades with considerably improved color fastness properties. In current years, concern for the environment has created an increasing demand for natural dyes, which are friendlier to the environment than are synthetic dyes. The aim of this work is to study the effect of dyeing cotton fabrics with both a natural dye (henna) and a synthetic dye (Remazol blue) on some mechanical properties and those of stability to light exposure. The undyed and dyed cotton fabrics were tested for their mechanical behaviors expressed as tenacity (N), elongation %, and work-breaking (N · m). They were also tested for shrinkage and crease recovery angle. The stability to light before and after 100 h exposure was examined by investigating the microstructure [using x-ray diffraction (XRD)] and macrostructure [using a scanning electron microscope (SEM)] and the reflection spectra. The results proved that the cotton samples dyed with Henna dye have higher mechanical properties than those dyed with “Remazol” reactive dye. Moreover, the light fading behaviors of both synthetic and natural dyes were studied in terms of the reflection spectra (400–800 nm), microstructure, and macrostructure of the sample's fibers.     

电磁搅拌对铝铜合金宏观组织及偏析的影响

为了改善铝铜合金在铸造过程中出现的密度偏析,研究了电磁搅拌对半固态Al-Cu合金宏观组织及偏析的影响。结果表明:电磁搅拌使得初生α-Al的径向分布更为均匀,改善了铸件的宏观偏析,且随着搅拌强度的增大,初生α-Al的分布也更均匀,即宏观偏析越小;电磁搅拌使得宏观组织显著细化,随着搅拌强度的提高,晶粒细化程度反而减弱。     

石英玻璃的结构缺陷及其形成机理

采用不同工艺制备4种石英玻璃,分析其结构缺陷及形成机理。结果表明,水晶粉为原料、石墨坩埚中熔制的Ⅰ类玻璃气泡、颗粒、条纹最多;高纯SiCl4原料、CVD工艺制备的Ⅲ、Ⅳ类玻璃无颗粒缺陷,气泡与条纹明显少于Ⅰ、Ⅱ类。Ⅱ、Ⅳ类玻璃经高温拉棒形成较大热应力,Ⅲ类玻璃熔体降温速度慢、热应力小。微观结构上,Ⅰ类玻璃金属杂质含量最高,Ⅱ类次之,Ⅲ、Ⅳ类都小于5×10-6。Ⅳ类玻璃在无氢的等离子火焰中熔制、羟基含量极低,Ⅱ、Ⅲ类在H2-O2焰中熔制导致羟基含量高。Ⅰ、Ⅱ、Ⅳ类玻璃氧空位含量较高,Ⅲ类玻璃基本不存在氧空位。     

工艺参数对气膜软接触连铸坯组织性能的影响

研究了气体种类、气体流量、拉坯速度等工艺参数对气膜软接触连铸坯组织性能的影响.结果表明:随气体流量的降低、拉坯速度的增大,铸坯的表面质量变差,宏观组织中的等轴晶比例降低,铸坯的皮下反偏析层厚度增大;气膜软接触连铸坯的力学性能明显高于传统DC连铸坯.