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Optimization of the welding parameters for Nd: YAG laser- and TIG welding in Greek ascoloy
2000 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

TIG (Tungsten Inert Gas) welding is used at VAC (Volvo Aero Corporation) for the production of TECs (Turbine Exhaust Cases). This technique implies a relatively high heat input to the component and, as a consequence, deformations and stresses. An optimization of the welding method is important in order to minimize these drawbacks. This research takes into account two welding methods: TIG, which is already used and well known at VAC, and Nd:YAG laser, which represents an alternative to TIG. In the literature study is presented a wide coverage of the theoretical aspects of the two methods. Other parts are dedicated to Greek Ascoloy, the material used for the fabrication of the TEC, to the martensitic stainless steels in general, to the theory of deformation, and to a statistical software (Modde) used for the preparation of some trial plans. The experimental part deals with the study of the TIG parameters already used at VAC and the research of improved parameters. The optimization is carried out for laser welding too, and in this case the study is even deeper since the process is new and relatively unknown for VAC. The butt-welding of sheet material was performed. Greek Ascoloy filler wire was always used while welding. Much time and many efforts were spent for the stabilization of the laser welding process, which at the beginning of the research was seriously affected by problems regarding the filler wire feeding. In some cases, deformation- and temperature measurements were carried out while welding in order to deliver useful data for another research which will study the modeling of the welding process. From the experimental part emerges one recommended set of parameters for each of the two techniques. These parameters could be the basis of further research, which could refine them. The improvement margin is still rather big, especially for laser welding which still produces welds affected by unwanted spatter on the underside. A particularly promising possibility for further improving of laser welding is the use of focal locations above the material’s surface. Recommendations for the future studies are also given, regarding both the use of other parameters and the improvement of the welding process.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Welding, TIG, GTAW, Nd:YAG laser, Greek Ascoloy, parameters, optimization
Keyword [sv]
URN: urn:nbn:se:ltu:diva-48212ISRN: LTU-EX--00/025--SELocal ID: 5b033ee3-a6f1-4e8e-80c3-ba931bfc1db8OAI: diva2:1021552
Subject / course
Student thesis, at least 30 credits
Educational program
Civil Engineering programmes 1997-2000, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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