A Study on Laser Weldability of Al-Si Coated 22MnB5 Steel for TWB Hot Stamping

Kim, Yong; Park, Ki-Young; Lee, Bo-Young

doi:2013.31.2.30

JWJ > Volume 31(2); 2013 > Article

Technical report

Journal of KWJS 2013 April;31(2) :30-36.
Published online June 5, 2013.

doi:https://doi.org/10.5781/KWJS.2013.31.2.30

A Study on Laser Weldability of Al-Si Coated 22MnB5 Steel for TWB Hot Stamping

Yong Kim, Ki-Young Park, Bo-Young Lee

Dept. of Aerospace and Mechanical Eng. Korea Aerospace Univ., Goyang 412-791, Korea
Center for Robot & Manufacturing, Institute for Advanced Eng., Yongin 449-863, Korea

Correspondence: Yong Kim Email: welding@iae.re.kr
Published online June 5, 2013

ABSTRACT

Recently the use of ultra high strength steels(UHSS) in structural and safety component is rapidly increasing in the automotive industry. Furthermore, it commonly use in tailor welded blank laser welding process before hot stamping to reduce lightweight vehicle. However TWB process is to be a problem about welded strength after hot stamping because it’s welded before heat treatment. Therefore, in this study, laser welds of TWB after heat treatment were analyzed for changes in the characteristics, especially the impact on the oxidation and decarburization in order to prevent pre-coated Al-Si layer welds on the properties for intensive investigation. As a result, the degradation of the TWB weldments changes in the heat treatment conditions alone, without any pre-treatment of the coating layer has confirmed that there is a limitation on the improvement. Furthermore Al-Si elements are overall distributed on the weldment and it specially concentrated along the fusion line. Hardness value of Al-Si segregation area is less than 350Hv and tensile strength showed just 78~83% compared with substrate. Accordingly, we proved that both side Al-Si coating should be removed in order to ensure the strength of the substrate.