激光-电弧复合焊接技术的研究现状

首先总结了激光焊和电弧焊的优缺点,然后根据复合热源的种类,分别介绍了激光-TIG焊、激光-plasma焊、激光-MIG焊复合热源系统,概括了每一种复合热源的原理、特点和国内外研究现状;介绍了激光-电弧复合焊接技术在汽车、船舶、航空等制造业中的应用。最后指出激光-电弧复合焊接技术的发展趋势。     

添加过渡层的镁合金/钢激光-TIG电弧复合熔化焊接机制

激光-电弧复合热源技术较单一热源焊接技术相比,具有热源能量密度梯度及热力耦合模式可优化设计等特点,成为实现关键零部件精确成形成性焊接制造的重要方法. 文中以镁合金/钢为代表的难固溶不反应异质材料为研究对象,提出多组元液相共存的镁合金/钢激光-TIG电弧复合焊接新思路,利用激光-TIG电弧复合焊接热源所具有的能量密度梯度分布特征,通过添加Cu-Zn过渡层,实现镁合金/钢异种金属高质量熔化焊接,并对铝元素的作用进行了探讨.     

镁合金/不锈钢激光-TIG复合焊的数值分析

应用Nd：YAG激光-TIG（非熔化极氩弧焊）复合焊接技术对AZ31B镁合金板和304L不锈钢板进行异种材料对接焊.根据复合焊接的能量耦合机理,建立了基于双椭圆平面分布、双椭球体积分布和旋转-高斯体积分布相结合的复合焊接热源模型,利用有限元数值模拟,分析了复合焊接温度场及残余应力分布.结果表明,对异种材料而言,焊缝处温度场差别较大,且镁合金侧的残余应力较高.     

镁铝异种金属激光-TIG复合热源焊焊接性分析

采用激光-TIG复合热源和TIG焊接异种金属镁和铝，利用X射线衍射仪、金相显微镜和扫描电镜研究镁和铝焊接接头的微观组织、元素分布。结果表明，TIG焊接镁和铝形成连续的金属间化合物层，导致镁和铝接触的界面开裂，不能实现有效的连接。激光-TIG复合热源由于其焊接速度高和对熔池的快速搅拌作用，使镁和铝形成的金属间化合物由连续的层状变成弥散的状态，改善了异种金属镁和铝的焊接性。镁和铝激光-TIG复合热源焊接的焊缝成形均匀，美观。     

激光复合焊接技术综述

首先对各种单热源焊接技术作了简单的叙述,介绍了单热源激光焊接的原理、特点及其优缺点。然后介绍了几种激光与其他能量形式复合的焊接方法,包括激光-TIG焊、激光-GMA焊、激光-等离子弧、激光双光束焊、激光与感应加热复合焊、激光与搅拌摩擦复合焊、激光-电、磁场复合焊等,阐述了这些复合焊接方法的原理、特点和研究现状,并指出了激光复合焊接技术的优势及其发展趋势。     

低功率YAG激光-TIG电弧复合焊接镁合金薄板工艺

以2 mm厚AZ31B变形镁合金薄板为研究对象开展低功率脉冲YAG激光-TIG电弧复合热源焊工艺研究,分析了激光与电弧的能量匹配对焊缝成形的影响规律.结果表明,镁合金薄板低功率YAG激光-TIG电弧复合热源焊接过程中,激光能量与电弧能量之间的相互匹配将直接影响焊缝的表面成形,获得理想焊接接头的工艺参数区间相对较狭小.为使焊缝成形均匀连续,焊接过程中需要对焊缝背面采用氩气进行保护,当保护气体流量为5～10 L/min时获得了具有最佳性能的焊接接头,其拉伸载荷达到镁合金母材的95%以上.     

激光-TIG复合焊接镁合金AZ31B焊接工艺

以变形镁合金AZ3lB为主要研究对象,研究激光-TIG复合热源焊接镁合金工艺特点,利用正交试验分析焊接规范对焊缝成型的影响。试验结果表明,激光束的存在增强了镁台金高速焊接时电弧的稳定性,增大了焊缝的熔深。在最佳的工艺条件下镁合金焊缝成型良好．无气孔、裂纹等缺陷,焊接接头抗拉强度与母材强度相当,表明激光-TIG复合热源焊接是一种理想的镁合金焊接新工艺。     

其它焊接方法

5A02／Q235钢Nd：YAG激光·脉冲MIG复合热源熔-钎连接;激光-TIG复合热源焊接参数对镁／钢异种材料焊接接头的影响;激光-电弧复合焊接咬边缺陷分析及抑制方法; 激光＋GMAW复合热源焊焊缝成形的数值模拟——Ⅱ．组合式体积热源的作用模型     

激光-电弧复合热源焊接技术

具有焊接质量好、焊接速度快等优点的激光-电弧复合热源焊接技术,已经广泛地应用于汽车、航空等工业的薄壁金属焊接中.然而,常用的激光源价格昂贵、体积庞大并且电-光转换效率低,大大限制了复合焊技术的推广和应用.新一代高性能激光-光纤激光的开发和应用拓宽了激光-电孤复合热源焊接技术的应用范围,使其更易于实现工程化.通过介绍当前世界上激光-电弧复合热源焊接技术的应用和研究情况,展现了激光-电弧复合热源焊接技术广阔的应用前景,阐述了其发展方向.     

其它焊接方法

高压钨极氩弧自动焊接，超薄板的MIG／MAG焊——CMT冷金属过渡技术,Nd：YAG激光＋脉冲MAG电弧复合热源焊接工艺参数对焊缝表面成形的影响,CO2激光-TIG复合热源脉冲协调焊接特性[英],[编者按]     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

Mechanism of Nucleation of Precipitates of Carbides of Refractory Metals Under Hot Rolling of Automotive Sheet Steel

Metal Science and Heat Treatment - The problem of formation of properties in microalloyed sheet steels is considered. The cause and the possible mechanism of precipitation of carbides of refractory...     

燃煤机组锅炉烟气脱硝灰中氨含量测定

NOx是大气环境的主要污染物之一,其主要来源为火力发电机组。依靠低氮燃烧技术,远达不到排放要求。选择性催化还原脱硝(简称SCR)技术是目前效率最高、最成熟、应用最广泛的电厂烟气脱硝技术。目前,在线氨逃逸监测技术存在诸多问题,影响了氨逃逸监测数据的准确度和稳定性。在燃料种类、炉膛结构、受热面布置、过量空气量、炉膛气流分布以及脱硝催化剂类型等条件确定的情况下,控制好氨加入量及其逃逸量是保证NOx脱除率的关键所在。燃煤锅炉除尘飞灰氨含量可侧面反映脱硝氨逃逸率的状况。根据国外的文献报道,正常情况下,电除尘灰中氨含量一般在50mg/kg-100mg/kg范围内。由于国内尚无灰中氨含量的测定方法,亦无脱硝运行对飞灰含氨量影响的数据积累。本文通过大量试验,确定了灰中氨溶解条件(如溶解时间、搅拌状态、灰水比、灰样量及其稳定性等),制定了灰中氨含量测定方法。     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.