2006 Volume 47 Issue 542 Pages 200-204
Problems related to differences in product dimensions occur in each case of the trial press working, the actual press working and the actual press working at different speeds. There are large differences in product dimensions of high-tensile sheet steels compared with that of SPCC (Cold-reduced carbon steel sheets). This study is based on the supposition that the cause of product dimension differences depends on changes in the material properties due to the working quantity and the working speed. To understand the actual conditions of this problem, the working quantity was replaced with strain and the working speed was replaced with strain rate, and effects of strain and strain rate on the r and n values were investigated. Three kinds of high-tensile sheet steels with SPCC were then compared. A uniaxial tension test was used, with specimens cut from the sheet at 0, 45 and 90 degrees to the rolling direction. A digital video camera was used to record every moment of change in the rectangle pattern printed on the specimens. An important result from the investigation showed that DP (Dual Phase) sheet steels have a larger dependence of strain on the n value compared with SPCC.
