Abstract
Key words
Body engineering, High strength stainless steels, Dual phase steels, Resistance spot welding, Laser beam welding, Gas metal arc welding, Database information
ABSTRACT
The European Automobile Manufacturers Organization (ACEA) has made a commitment to the European Community (EC) to reduce the amount of CO2 emissions deriving from passenger cars. Each manufacturing brand must not exceed an average 140 g CO2 emission per driven kilometre for the whole fleet of newly produced passenger cars. This figure should be valid from 2008 with an optional extension to 120 g/km from 2012.
To meet these pre-conditions, the contribution from body engineering and manufacturing is spelled weight saving. The issue can be summarized in three main groups:
• Reduction of the number of parts in the car body
• Down-gauging sheet thickness in combination with the introduction of continuous joining methods
• Substitution of traditional sheet steels with other lightweight materials
One alternative which lately has received attention is to integrate various grades of high strength stainless steels into the body structure. This paper will briefly discuss the overall consequences of introducing such a material, regarding formability, corrosion and impact behaviour etc. From experience we know that outstanding car body properties can only be reached if the choice of materials, body concept and joining methods is done in an integrated process. One obvious challenge for mixed materials scenarios is of course the need to secure a high quality joining process for these material combinations.
Therefore the paper will focus on the process feasibility of welding high strength stainless steels to zinc coated Dual Phase (DP) steels in various thickness combinations. Three commonly used assembly techniques for Body-in-White (BIW) manufacturing have been investigated; Resistance Spot Welding (RSW), Laser Beam Welding (LBW) and Gas Metal Arc Welding (GMAW). Alongside the manufacturing related activities, investigation of these joints at static and fatigue loading have also been tested and recorded. The paper will conclude the results and give recommendations about body components which could be suitable to manufacture in high strength stainless steels concerning a weight savings/cost efficiency ratio. It will also summarize how all the engineering and manufacturing data generated are easily accessed world-wide through the global Join-NET© database, which functions will be briefly described.