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Laser welding of aluminium is of high interest among the industrial production. Light weight, good corrosion and mechanical properties make aluminium very important material. High reflectivity and high thermal conductivity, high vapour pressure of alloying elements as well as low liquid surface tension and low ionisation potential, make laser welding of aluminium and its alloys a demanding task. Problems that occur during welding are mainly caused by process instabilities of the keyhole and the melt pool, increased plasma formation above the melt pool and loss of alloying elements. These problems lead to unwanted metallurgical defects like hot cracks and porosity in the weld bead and other problems concerning the shape and appearance of the weld bead. In order to minimise the defects and improve the weld quality, the process and beam parameters need to be carefully adjusted along with a consideration concerning the use of filler wire for the welding process. In this paper the welding of 3.0 mm thick grade 5083 aluminium alloy plates using a 3.0 kW Nd:YAG laser with grade 5183 filler wire addition is investigated. The plates were welded as butt joints with air gap sizes 0.5 mm, 0.7 mm and 1.0 mm. The analysis of the weld beads obtained from the welded samples showed that the least imperfections were produced with 0.7 mm air gaps at moderate welding speeds. The analysis also covered the calculation of the melting efficiency and the study of the shape of the weld bead. The melting efficiency was on average around 20 % for the melting process of the welded plates. The weld beads showed the characteristic V-shape of a laser weld and retained this shape during the whole series of experiments.Laser welding of aluminium is of high interest among the industrial production. Light weight, good corrosion and mechanical properties make aluminium very important material. High reflectivity and high thermal conductivity, high vapour pressure of alloying elements as well as low liquid surface tension and low ionisation potential, make laser welding of aluminium and its alloys a demanding task. Problems that occur during welding are mainly caused by process instabilities of the keyhole and the melt pool, increased plasma formation above the melt pool and loss of alloying elements. These problems lead to unwanted metallurgical defects like hot cracks and porosity in the weld bead and other problems concerning the shape and appearance of the weld bead. In order to minimise the defects and improve the weld quality, the process and beam parameters need to be carefully adjusted along with a consideration concerning the use of filler wire for the welding process. In this paper the welding of 3.0 mm thick grade...

Laser welding has the potential of offering both technical and economical advantages in many applications in the shipbuilding industry. A limiting factor is currently the power level available with commercial lasers, since steel plates above 5 mm in thickness are used in almost every shipbuilding application. In addition, the high hardness of the welds produced using laser welding is a disadvantage when compared with the requirements of existing classification society standards. It has been reported that by using a hybrid welding method, in which a laser beam and a GMAW arc are combined, it is possible to weld thicker sections, because penetration is increased. Hardness values are correspondingly lower than with the laser process because of the increased energy input.Results of a study of hybrid high power Nd:YAG laser and GMA welding are reported. All plates were welded in a butt joint configuration. When laser and GMAW were combined in a single process, I -grooves were used. The air gaps between the welded plates were varied. Some tests were made using a partially-grooved V joint. In these cases, the root faces were welded by using Nd:YAG laser, and the upper part of the joint was welded by GMAW. It was seen that it is possible to produce defect-free welds using these processes. Macrosections of the welds, hardness values and parameters are presented and discussed.Laser welding has the potential of offering both technical and economical advantages in many applications in the shipbuilding industry. A limiting factor is currently the power level available with commercial lasers, since steel plates above 5 mm in thickness are used in almost every shipbuilding application. In addition, the high hardness of the welds produced using laser welding is a disadvantage when compared with the requirements of existing classification society standards. It has been reported that by using a hybrid welding method, in which a laser beam and a GMAW arc are combined, it is possible to weld thicker sections, because penetration is increased. Hardness values are correspondingly lower than with the laser process because of the increased energy input.Results of a study of hybrid high power Nd:YAG laser and GMA welding are reported. All plates were welded in a butt joint configuration. When laser and GMAW were combined in a single process, I -grooves were used. The air gaps between the wel...

Laser welding gives designers increased freedom in material selection and joint design, in comparison with many conventional joining techniques. Butt, lap and T -joints are typically used when laser welding sheet materials. The presence of an air gap between the sheets affects weld quality - it is recommended that no air gap is present in a butt joint, if an acceptable weld is to be produced. Although an air gap should be avoided in lap and T – joints, to avoid weld defects, an air gap is necessary in some cases, e.g. when welding zinc-coated sheets. Data for acceptable air gaps are also needed in order to be able to specify appropriate fixturing, based on economic and technical criteria. If a small air gap is acceptable, expensive fixturing that ensures no air gap is not necessary.The results of an investigation into high power Nd:YAG laser welding of low strength mild steel, in sheet thicknesses of 0.75 and 1 mm, using lap and T-joints (welded in a stake joint configuration), are reported and discussed. Some of the specimens were zinc-coated. The effect of an air gap on the weld properties was studied in both joint configurations, in order to establish the fixturing accuracy required in practical applications, as well as its effect on the formation of pores when welding zinc-coated sheets. Laser power levels up to 3 kW, and welding speeds up to 10 m/min were used. The focal plane position was varied in order to control the weld bead profile to ensure a satisfactory weld section in the joint. The following were characterized from transverse weld sections: penetration and bead profile; geometry of the bead root and face; effective weld area in the joint with regard to the accommodation of weld defects. Tensile tests and hardness profiles were also made on some of the welds.The results show that in the case of a stake-welded T-joint, the most important factors controlling weld quality are the size of the air gap between the web and the flange, and the alignment of the laser beam with the web sheet. An air gap of 0.1 mm can be tolerated with a sheet thickness of 1 mm, provided that the laser beam is aligned with sufficient accuracy. The same air gap can be tolerated in a lap joint configuration with a sheet thickness of 1 mm. A zinc coating density of 100 g/m2 was used. No pores were found from a macroscopic examination of sections.Laser welding gives designers increased freedom in material selection and joint design, in comparison with many conventional joining techniques. Butt, lap and T -joints are typically used when laser welding sheet materials. The presence of an air gap between the sheets affects weld quality - it is recommended that no air gap is present in a butt joint, if an acceptable weld is to be produced. Although an air gap should be avoided in lap and T – joints, to avoid weld defects, an air gap is necessary in some cases, e.g. when welding zinc-coated sheets. Data for acceptable air gaps are also needed in order to be able to specify appropriate fixturing, based on economic and technical criteria. If a small air gap is acceptable, expensive fixturing that ensures no air gap is not necessary.The results of an investigation into high power Nd:YAG laser welding of low strength mild steel, in sheet thicknesses of 0.75 and 1 mm, using lap and T-joints (welded in a stake joint configuration), are reported and discussed....