Relevance of Inclusions on Formability in Punch-Stretching of Low-Carbon, AK, DQ Steel

摘要

To investigate the relevance of inclusions on automotive sheet metal formability, void volume fractions and void size distributions from a set of punch-stretched, low carbon steel specimens were measured. Measurements from strain states corresponding to instability in uniaxial tension, plane strain, and positive biaxial stretching were compared. Overall void volume fractions were low (on the order of 1 to 2 tenths of a percent), as were the void sizes (mean size of 8 square microns) for all strain states examined. The growth of voids was measured and was found to be in agreement with the model adopted by Jalinier and Schmitt. Based on experiments in punch stretching and analysis for instability in uniaxial tension, it was concluded that the current level of inclusions found in low carbon AK, DQ, sheet steels does not impose a significant limit on formability. (ERA citation 11:004707)