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Forming Limit Diagrams (FLD) are extensively used in North American press shops during tooling trials and in production for problem identification/resolution. The Keeler-Goodwin FLC shape and the correlation developed by Keeler and Brazier (based on n-value and thickness) have been widely accepted as the Standard FLC Method to predict forming limit curves for commercial steels. In this paper, the Standard FLC Method is reviewed, and an alternative approach used at the authors' laboratory (Bethlehem FLC Method) is described. The two methods are discussed in the context of more recent experimental determinations of FLC's for a variety of “modern” sheet steels including DQSK, Interstitial Free and Bake-Hardening steels, as well as coated sheet products. Some specific press-shop examples are also presented, which further highlight the value to industry of re-examining the Standard FLC Methodology used in circle-grid analysis.

Corrosion resistance has been the major impetus toward increased use of galvanneal and other coated sheet products by the automotive industry. Galvanneal has the additional advantages of good weldability, due to the iron in the coating, and a higher surface porosity which leads to better paint adhesion. The porosity of the galvanneal surface, however, could also lead to reduced cleanability. This paper reports the effects of pretreatment variables on galvanneal phosphatability and resulting painted corrosion performance. The studies showed that the rust preventative oil applied and the alkaline cleaner used to clean samples prior to phosphating had significant effects on carbon residuals after cleaning. The painted corrosion performance of galvanneal panels with various levels of residual carbon showed a much smaller effect within a given cyclic test. The studies also indicated significant differences in performance depending on the type of cyclic test performed.