A System for Comparing High Strength Steels for Automotive Integral Body Structural Rail Type Parts

The paper describes a system for comparing different steels for use in automotive integral body structural rail type parts. Methodology is described for estimating yield strength, tensile strength, and thickness after forming and paint bake aging. Methods are also referenced for using these data to estimate maximum load capacity of structural members at collision loading rates and to estimate the ability to absorb collision energy. With these (or other) design methods, the material strength properties can be directly related to part performance. Indices are also developed that may be quantitatively relatable to the practical difficulties in controlling curl and springback in high strength steel. For splitting tendency during forming, important steel characteristics are identified, but no methodology is provided to quantitatively relate these parameters to part performance. Representative data for all steel properties used in these approaches are provided for one or two samples of hot dip galvanized SAE 940×, 950×, and 960×. With these data, it is shown how the system can be used to compare these different steels for rail type part applications.