In new car production an innovative method to produce strong and light panels consists in applying Tailor-Welded Blanks (TWBs) in the body-in-white base structure. The TWBs technological concept consists in producing panels composed of several sheet metal blanks, that may be of different material grades, strengths, gauge thickness or coatings, that are welded together prior to the forming process. Since the fusion welding processes can induce significant differences between the material properties of the weld and the base materials, an important question is whether the weld bead, usually very narrow, has a significant influence on the overall behaviour of the welded blanks. Tailor welded blanks were made with a 3 kW power diode laser in 1 mm thick sheet plates of two commercial steel alloys very popular in automotive industry: DC06 and DP600. The TWBs were produced in similar (DP600/DP600 and DC06/DC06) and dissimilar (DP600/DC06) combinations of both materials. Metallurgical and mechanical characterisation of the welds were also performed, in order to help understanding the formability performance of steel TWBs. Hardness measurements evaluated the mechanical heterogeneity of each weld. Deep-drawing of axisymmetric cups with 60 mm height assessed the formability of the TWBs. These tests were made with a laboratorial deep-drawing device developed to work on a classical tensile test machine. The welding operation made some changes in the microstructure and hardness of the welds in the TWBs of the same material. The weld mechanical properties of the TWBs composed of a single material almost didn't affect the forming behaviour of the cups, face the monolithic results. For the TWBs of dissimilar materials, an abrupt change in microstructure and hardness happened approximately in the middle of the weld. In this case it was impossible to achieve the prescribed deep-drown depth of the cup.


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    Title :

    Formability of laser welded steel sheets


    Additional title:

    Umformbarkeit lasergeschweißter Stahlbleche


    Contributors:


    Publication date :

    2006


    Size :

    8 Seiten, 12 Bilder, 2 Tabellen, 11 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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