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| 2. |
- Forsman, Tomas, et al.
(författare)
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Initiation and termination phenomena in laser welding of aluminum
- 2000
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 12:2, s. 81-84
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates a defect problem related to laser welding of tailored aluminum blanks. During the initial few millimeters of welding the weld was intermittent. By applying an analytical line source model the weld was shown to experience overheating close to the starting edge. This overheating was reduced by ramping the power during the initial 100 mm and this made the defects disappear. Al sheets of 0.1mm thickness with milled edges were butt welded and bead-on-plate welded in the present investigation.
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| 3. |
- Forsman, Tomas, et al.
(författare)
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Nd:YAG laser lap welding of coated aluminum alloys
- 1997
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Ingår i: Proceedings of the Laser Materials Processing Conference. - Orlando, Fla : Laser institute of America. - 0912035560 ; , s. G113-G120
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Konferensbidrag (refereegranskat)abstract
- This experimental program investigated the production of lap welds between 1 mm thick sheets of aluminium alloys 5182 and 6016 which had previously been coated with Drylube. (Drylube is a polymer based coating approx1 mu m thick which improves the formability of the aluminium alloy sheet). Successful welds were produced using a 2.5 kW Nd:YAG laser in conjunction with a 0.6 mm optical fibre. It was discovered that there is an optimum gap width between the two sheets which gives the best weld quality and strength. Pulsed and CW laser welds were produced and compared with respect to porosity and surface profile, etc
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| 4. |
- Forsman, Tomas, et al.
(författare)
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Nd:YAG laser welding of aluminium : factors affecting absorptivity
- 1999
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Ingår i: Lasers in engineering (Print). - 0898-1507 .- 1029-029X. ; 8:4, s. 295-309
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the factors affecting the absorptivity during Nd:YAG laser keyhole welding of a 6xxx aluminum alloy. The influence of surface condition on absorption is shown to be negligible. Experimental absorption measurements by calorimetry are compared to analytical absorption values using a simple model based on Fresnel absorption during multiple reflections in the keyhole.
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| 5. |
- Forsman, Tomas, et al.
(författare)
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Nd:YAG laser welding of coated aluminium sheet with a new dry lubricant film
- 1998
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Ingår i: Svetsen. - 0039-7091. ; 57:3, s. 10-12
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Tidskriftsartikel (refereegranskat)abstract
- Trials are reported of the Nd:YAG laser welding of sheet of thickness about 1 mm in two aluminium alloys (AA-5182 (Al, 4.0-5.0%Mg) and AA-6016 (Al, 0.3-0.6%Mg, 1.0-1.5%Si)) coated with "Drylube" dry lubricant (some with zinc passivation first). Effects were investigated of welding conditions (constant or pulsed operation, gap of 0.0-0.3 mm) on porosity, penetration, and microcracking at the fusion boundary. Weld cross-sections are presented. Results are given also of hardness and tensile tests.
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| 6. |
- Forsman, Tomas, et al.
(författare)
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Prediction of the cross-sectional geometry of Nd:YAG laser welds in aluminum alloys
- 2000
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Ingår i: Proceedings of the Laser Materials Processing Conference. - Orlando, Fla. : Laser institute of America. - 0912035609 ; , s. E156-E165
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Konferensbidrag (refereegranskat)abstract
- This paper describes an analytical model for determining the geometry of laser welds. An earlier model by Lampa and Kaplan (1997), for CO2 laser welding of stainless steel, has been further developed to cover Nd:YAG laser welding of aluminium alloys. This analytical work was followed by experimental verification using a 4 kW Nd:YAG laser. The model was found to be accurate over a wide range of process parameters
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| 7. |
- Forsman, Tomas, et al.
(författare)
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Process instability in laser welding of aluminum alloys at the boundary of complete penetration
- 2001
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 13:5, s. 193-198
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Tidskriftsartikel (refereegranskat)abstract
- Intrinsic instabilities in the depth of penetration achieved when laser welding aluminum alloys were investigated in this article. Four types of weld pool configuration, resulting in different welds, were identified, only two of which are associated with full penetration. A simple phenomenological explanation of the unstable welding process at the boundary of complete penetration was proposed. The nature and cause of the instabilities were discussed and suggestions were offered for process control. Materials used: AA6016 aluminum alloy.
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