| 2. |
- Ion, John
(författare)
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Laser beam welding of wrought aluminium alloys
- 2000
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Ingår i: Science and technology of welding and joining. - : Informa UK Limited. - 1362-1718 .- 1743-2936. ; 5:5, s. 265-276
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Tidskriftsartikel (refereegranskat)abstract
- Laser beam welding is now a common manufacturing method for a wide range of steel products from automobiles to razor blades. However, the process has only recently been approved for critical applications involving aluminium alloys, notably in the aerospace and automotive industries. The properties of aluminium alloys influence the interaction between the beam and the material to a far greater extent than for steels. The challenge of developing industrial welding procedures has therefore been considerable. The present review describes the effects of CO2 and Nd-YAG laser beam processing parameters and the properties of the most common wrought aluminium alloys on the characteristics of welded joints. Porosity, solidification cracking, and poor weld bead geometry are shown to be the most frequently encountered imperfections. These can be eliminated through the use of appropriate filler materials, process gases, material preparation, and in some instances, adaptive control systems. Very little work has been reported on the corrosion properties of laser welded aluminium alloys. Experimental processing parameters are presented and compared using an analytical model, which can also be employed for predictive purposes. A number of industrial applications are described. These demonstrate that, for specific alloys, the process is now sufficiently well understood to be approved for high volume production, particularly in the transport industries.
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| 3. |
- Winkler, C., et al.
(författare)
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Effect of surfactant redistribution on weld pool shape during gas tungsten arc welding
- 2000
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Ingår i: Science and technology of welding and joining. - : Informa UK Limited. - 1362-1718 .- 1743-2936. ; 5:1, s. 8-20
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Tidskriftsartikel (refereegranskat)abstract
- In previous evaluations, of GTA welding stainless steel plates the surfactant content in the workplace has been assumed to be in a state of equilibrium. However surfactant concentration usually had to be adjusted in order to achieve agreement between the weld pool shapes in experiments and those in simulations. In this study a physiochemical approach to the redistribution of surfactant at the surface and in the bulk is presented for the first time. Sulphur was considered as a represenative surfactant. The model allows surfactant molecular transport via convection, diffusion, and sorption. It is shown that sulphur atoms accumulate at the surface at stagnation points, affecting the coefficient of surface tension and thus the final weld pool shape. Thus, the sulphur content in the simulation approaches the nominal sulphur content in the steel plate. The theory is strenghtened by both electron probe microanalysis and Auger electron spectroscopy. At the time the work was carried out, Mr Winkler, Dr Inoue and Mr Fuji were at the Welding and Joining Reserach Center, Steel Reserach Laboratories, Technical Development Bureau, Nippon Steel Corp., 20-1 Shintomi, Futtsu, Chiba 293, Japan, Dr Amberg was in the Department of Mechanics, Royal Institute of Technology, Osquars Backe 18, 100-44 Stockholm, Sweden, and Dr Koseki was at the Oita R&D Laboratories, Nippon Steel Corp., 1 Nishinosu, Oita 870, Japan. Mr Winkler is now in the Department of Mechanics, Royal Institute of Technology, Manuscript received 4 March 1999; accepted 8 April 1999.
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