Browse Publications Technical Papers 2011-26-0058
2011-01-19

Inflatable Side Impact Beams in Martensitic Steel 2011-26-0058

In automotive design, higher safety requirements, lower weight and CO₂ emissions, and compact design, all speak for the use of ultra-high-strength steels. But still today there is a lot of caution when such steels are used, due to presumed lack of formability and the ductility in the material after forming. In the current paper, a design in the ultra-high-strength steel Docol 1200 M will be shown, which clearly shows the potential in terms of safety and compact design when using such steels, but also the formability and ability to withstand deformations in a crash situation of the steel involved.
The application is an inflatable side impact beam for a passenger vehicle. The inflatable side impact beam is a compact module made of thin-walled metal and pyrotechnics comparable to the ones used for airbag application.
Within a few milliseconds, inflation causes thin-walled metal to deform/expand and the pressure to increase up to 20 bar inside the structure.
Larger cross-section beam provides then similar or higher impact performance and increased protection of occupant with lower weight.
The material used for the structure is Docol 1200 M, an ultra-high-strength cold-rolled martensitic steel. The steel, which is delivered in quenched condition, has a minimum tensile strength of 1200 MPa, and is cold formed to the structure shown in picture below. The part was formed to the final shape in two forming steps, after which it was assembled with the bottom part with the pyrotechnics inside. Details of the forming process are given in the paper.
The application shows the possibilities which exist when new thinking is combined with new, ultra-high-strength steel grades.

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