EFFECTS OF BLANKING CONDITIONS TO EDGE CRACKING IN STAMPING OF ADVANCED HIGH STRENGTH STEELS (AHSS)

Paper #:
  • 2018-01-0626

Published:
  • 2018-04-03
Abstract:
Practical evaluation and reduction of edge cracking are very challenging issues in stamping AHSS for automotive body structures. In this paper, the effects of two key shearing parameters (the shear clearance and shear rake angle) to edge cracking were investigated with three different grades AHSS, TRIP780, DP980 and DP1180. Five different shear clearances were selected between 5% and 25% sheet thickness. The shear loads were compared and the shear edge quality was thoroughly characterized and compared. The shear peak load and the burr height increased from increasing the shear clearance. The sheared samples under different shearing conditions were tested using the Half Specimen Dome Test (HSDT). The HSDT created the edge forming limits as compared to the base material forming limit diagram. Load-displacement curve was measured using the load-cell and the strain distribution was measured during the test using a Digital Image Correlation (DIC) system during the test. The best shear clearance was determined for different sheet materials based on the maximum punch stroke onset of edge cracking as well as the DIC measured major strain/thinning values. The results showed that TRIP780 showed the minimum edge cracking with 15% shear clearance while both DP980 and DP1180 gave the minimum edge cracking with 20% shear clearance. The DIC measured thinning value onset of edge cracking was used as major input data for prediction of edge cracking using a commercial FE software, PAM-STAMP. Simulation results showed reasonably good correlations with experimental observations. The shear peak load was found to be a good indicator for shear edge quality and the resulting hardness on sheared edge. TRIP780 and DP980 showed the most sensitivity of shearing-induced hardness increase to edge cracking increase. However, DP1180 showed relatively lower sensitivity of hardness increase to edge cracking, because DP1180 was observed to relatively small hardness variations between the sheared edge and base metal compared to TRIP780 and DP980. For industrial application, the shear load can be monitored to obtain high quality shear edge with AHSS. The burr height can be monitored after shearing operation using the real-time monitoring tool to indicate the shear edge imperfection and its effect to the edge stretchability.
Access
Now
SAE MOBILUS Subscriber? You may already have access.
Buy
Attention: This item is not yet published. Pre-Order to be notified, via email, when it becomes available.
Select
Price
List
Download
$22.00
Mail
$22.00
Members save up to 36% off list price.
Share
HTML for Linking to Page
Page URL

Related Items

Technical Paper / Journal Article
2011-05-17
Technical Paper / Journal Article
2011-05-17
Event
2018-04-10