Analysis of the criteria for evaluating the wetting capacity of materials in brazeability tests

The technique that can measure the transient welding deformation directly is very important for investigating the mechanism of welding deformation. In this study, an in-situ displacement measurement method using digital camera is self developed. This system is non-contact type and it does not need any complicated optical systems but it can measure the in situ displacement over the full field high accuracy using digital image correlation technique. Therefore, it is considered to be useful and easy to apply to practical problems. The number of measuring points that can be obtained at a time is more than 10 million. It is the same as the available pixels of the digital camera. Furthermore, since the active light source is not necessary in this system, the influence of the fluctuation of the atmosphere caused by the high temperature area is small. In this study, the detail of the proposed system is given and it is applied to the transient in-plane deformation problem under very high brightness lightened by welding arc. Through the comparison between the experiment and thermal elastic–plastic finite element analysis, the validity of the transient transverse shrinkage distribution which is measured by the proposed system is verified. The residual deformation is also investigated to check the accuracy and usefulness of the proposed system.     

轻金属焊接变形检测与控制技术研究进展

随着工程结构向减重与节能方向发展,轻金属焊接结构在工程中得到越来越广泛的应用,轻会属焊接结构制造中焊接变形问题成为焊接领域的研究热点与共性课题,如何进行焊接变形的精确检测进而实现有效控制,成为重要的研究方向.该文结合在国家自然科学基金等项目的支持下本课题组在此领域取得的研究成果,综述了焊接变形检测与控制技术的研究现状与未来发展方向.     

Al-Mg(Sc,Zr)合金焊接接头组织与性能试验研究

对比了以Al-Mg及Al-Mg-Sc合金焊丝为填充材料,手工TIG法施焊的Al-Mg-(Sc,Zr)合金焊接接头微观组织特征及力学性能。结果表明,基材热影响区没有发生明显的再结晶现象,证明Al-Mg-(Sc,Zr)合金具有很强的抗焊接热软化能力;采用Al-Mg-Sc合金焊丝为填充材料时焊缝晶粒组织得到明显细化,提高了焊缝强度;熔合区形成的细小等轴晶层提高了基材与焊缝填充材料的结合力。采用Al-Mg及Al-Mg-Sc合金焊丝焊接时,Al-Mg-(Sc,Zr)焊接接头强度系数均大于0.90;但采用Al-Mg合金焊丝时,焊接接头屈服强度仅为188 N/mm2,而采用Al-Mg-Sc合金焊丝时,焊接接头屈服强度高达287 N/mm2,大大提高了Al-Mg-Sc合金焊接构件的许用强度。     

Scientific and technological fundamentals for the development of the controlled short-circuiting MIG/MAG welding process: a review of the literature. Part 2 of 3. Metal droplet formation,shield gases,penetration mechanisms,heat input and economical aspects

The second part of this series deals with the metal transfer modes of most interest to the MIG/MAG process, regarding the development of the controlled short-circuiting MIG/MAG welding process (CCC). The primary intention is to study pulsed arc and short-circuiting arc welding, both of which are the basis for the CCC. Also in relation to the metal transfer dynamics, the drop formation and the forces acting on it are reviewed. To provide a more complete understanding, aspects regarding shielding gases are described, including economic issues. Since they are important characteristics for any weld, information concerning short-circuiting MIG/MAG welding penetration and heat input are also provided.