Lightweight design is one of the central topics for the future of the automotive industry. The usage of air-hardening steels in manufacturing of cars and trucks can lead to significant weight reduction. These high-strength steel grades sustain most complicated deformation processes and ensure high component durability. In the soft delivery state, the blanks can be excellently formed into highly complex components using deep drawing or other modern forming techniques. As a welded pipe, the steel can be formed using hydroforming processes without intermediate annealing. With a subsequent heat treatment, tensile strength levels higher than 800 MPa can be achieved. In this case, the components are heat-treated after forming under a protective gas atmosphere and finally hardened with natural cooling in air or inert gas. Thanks to the combination of high strength and ductility of the steel, the integral support member has a high capacity to absorb energy during a crash and yet remains insensitive to the occurring high operating loads. The selected air-hardening steel was first used in the integral support BR212 of the current Mercedes E-class. While in this case the steel remained in the soft state, the air-hardening potential of the selected steel grade is now fully utilized in the longitudinal beams of the integral support member of the new Mercedes-Benz C-Class, in order to meet the increased demands on structural durability and crash performance requirements. In particular, the advantages of the material concept of air-hardening steels come to fruition in local strengthening of such component parts that are exposed to higher loads. Due to the specific steel composition, the conditions of quenching and tempering treatment were simplified. The tempering of the longitudinal beams that are air-hardened in a continuous furnace is now carried out during the baking treatment of the cathodic dip coating of the welded assembly.


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    Title :

    Application of air-hardening steels for highly stressed structural parts with simplified heat treatment


    Additional title:

    Anwendung der lufthärtender Stähle für hochbeanspruchte Bauteile mit vereinfachter Wärmebehandlung


    Contributors:


    Publication date :

    2014


    Size :

    8 Seiten, 8 Bilder, 2 Tabellen, 5 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English