Optimierung der Herstellung lasergeschweißter Fülldrähte für das Schweißen hochfester Stähle

Research output: ThesisDoctoral Thesis

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Abstract

The use of high strength steels is increasing, due to the demands of industry in light weight constructions. The welding industry follows this trend which leads to the development of adapted flux cored wires to reduce the risk of hydrogen embrittlement. New afford is made for a fully closed wire to save the filling from penetrating water, dirt and oil. In the production process a laser is integrated after roll forming of a tube and before the diameter reduction. With the laser-welding different conditions have to be met, like reduced oscillations of the strip and parallel edges. A high quality of the welding seam is an essential factor for the following diameter reduction. The second great factor is the powder filling. The properties influence the forming during the reduction. These problems give a short overview how the parameters interact during the production. With finite element analyses the production steps were analyzed. For the roll forming the software Abaqus and Copra were compared and afterwards new roll geometries were developed. In the second step an investigation of the laser settings has been done. Afterwards the diameter reduction is investigated. The high impact of the powder compaction on the forming was discovered. With simulations a sensitivity analysis is done on the roller die geometry, the welding seam size and hardness and different internal pressure as a factor of the powder compaction. The effect on the stress distribution, drawing force and force on the rolls is compared. Over all a good understanding of the production was established and optimizations were worked out.

Details

Translated title of the contributionOptimization of the production process of laser-welded flux cored wires
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
Publication statusPublished - 2012