In recent years, weight reduction and improvement of automobile crashworthiness by use of high strength steel sheets has been actively promoted to reduce CO2 emissions and improve passenger protection. TS1470 MPa grade quenched steel pipes and hot-stamped parts are already used as the door impact beam, which is a reinforcement part inside the door. However, because quenched steel pipes require quenching and tempering treatment after pipe making process, and brackets must be arc welded to both ends of the pipes for joining with the door, the cost of these parts is high. Therefore, this research was carried out with the aim of developing a one one-piece rear door impact beam by an economical cold-stamping process. The technical issues in developing cold-stamped door impact beems were securing a level of crashworthiness and manufacturability equivalent to the former hot-stamped part, and ensuring safety against delayed fracture. The results of studies of these respective issues are presented in this article. Cold-stamped door impact beams made of TS1180 MPa grade cold-rolled high strength steel have been developed. The newly developed parts achieved both weight and cost reductions compared to former hot-stamped parts. Cold-stamping was successfully performed by using a newly developed high strength steel sheet with high ductility. To avoid delayed fracture, conditions (applied stress, strain and hydrogen) in which hydrogen cracking of the steel occur were drawn up on a map and then applied conditions of the parts were set accordingly at safe levels far from the hydrogen cracking regions indicated on the map.


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    Title :

    Development of cold-stamped door impact beams made of 1180 MPa grade high strength steel sheet


    Additional title:

    Entwicklung von kaltgeformten Flankenschutzbalken aus hochfesten Stahlplatten der Güteklasse 1180 MPa



    Published in:

    Publication date :

    2009


    Size :

    7 Seiten, 18 Bilder, 10 Quellen



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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