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2010
Conference Paper
Titel
Hybrid laser welding of thick section steels - the hyblas project
Abstract
An European Research Fund for Coal and Steel (ERFCS) funded project named HYBLAS was completed at the end of 2007 and had the overall aim of extending the applicable range of hybrid laser welding from 12 to 30 mm thick steels. This paper will summarise the results of the project, concentrating on the development of the techniques and processes which enabled 20-25mm thick steels to be welded in one pass and how multi pass welding can extend this even further. The project had 6 partners from 4 countries and in addition to the welding process developments, which were carried out by two of the partners using different laser systems, included extensive studies of the fatigue and fracture properties of the welded joints in order to justify their acceptability for use in industrial fabrications. For a similar reason the factors which govern the occurrence of welding defects have been identified so the effective safe welding limits can be defined for a wide range of application s. Steel types with yield strengths between 180 and 690 MPa have been studied and operational windows for defect free welding were found. In addition various NDE methods were studied for their efficiency in regard to the defect types which can occur in laser hybrid welds. The fracture and mechanical properties of the joints were shown to be perfectly acceptable for all structural uses and an extensive fatigue testing programme demonstrated that the fatigue behaviour of the welded joints exceeded conventional welding expectations. Finally full scale industrial components were manufactured, inspected and tested to demonstrate that the anticipated fatigue benefits were obtained.