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In an effort to optimize outer body panel steel utilization with respect to dent resistance performance and weight reduction, the automotive industry continues to investigate the application of higher strength steels. Most recently, dual phase steel has been recognized as a very promising material substrate for outer body panel application, due to its inherent formability and final part performance attributes. This paper presents a comprehensive study of Ispat Inland's new electrogalvanized dual phase “DI-FORM 500” product, which was specifically designed to meet automotive exposed quality standards. It reviews the mechanical properties, aging characteristics, formability, dent resistance, weldability and fatigue strength of this product, along with a representation of its application advantages to the automotive industry, in terms of part performance, weight savings and cost avoidance.

With interest in improving vehicle quality and customer satisfaction, Ford Motor Company initiated an effort aimed at improving dent resistance of closure panels. An investigation of various means of product improvement led to the recognition of dual phase steels, due to their inherent formability and strain hardening attributes, as the most appropriate steel panel for outer panel applications. Ispat Inland's new Electro-galvanized dual phase steel DI-FORM 500 (henceforth referred to by the generic designation, DP500), which meets 500 MPa minimum tensile strength, was specifically designed to meet automotive exposed quality standards. This paper compares the dent resistance performance of automotive door assemblies manufactured with both Bake Hardenable 210 (BH210) and DP500 door outer panels. Results indicate the achievement of significantly improved outer panel dent resistance through the use of the DP500 product.

Prediction of dent resistance of automotive closure panels using Finite Element Analysis (FEA) has increased in popularity as an effective screening tool to determine the optimum combination of material properties and thickness for a given exposed panel application. The analysis process typically includes formability analysis, the results of which are mapped onto a structural model for analysis of dent resistance. Although this method is general, allowing for consideration of the entire panel assembly and boundary conditions, the approach can be very time consuming especially when evaluating several combinations of material grade and thicknesses. This paper presents an alternative approach for the prediction of dent resistance. Using a number of screening simulations the most influential variables affecting dent resistance were determined. A rectangular bi-curved plate was used to approximate the panel assembly.