Research on the different Behavior of Edge Cracking Limit by Adopting the Laser Cutting Method 2019-01-1264

The edge fracture occurs more frequently during the forming procedure by using the material with higher strength. To avoid the edge fracture that happens during the manufacturing, the edge cracking limit at different pre-strain level needs to be determined. The edge of the part under forming is conventionally manufactured by mechanical cutting, and the edge cracking limit under this circumstance is already heavily studied. In recent years, laser cutting is more applied in the automotive industry to cutting the edge due to the following advantages over mechanical cutting: easier work holding, higher precision, no wearing, smaller heat-affected zone, etc. The change cutting method could lead to a different behavior to the edge cracking limit at different pre-strain level. In this paper, the edge cracking limits of sets of pre-strained coupons with different pre-strain levels are tested. Half of them is cut by the conventional punch method, and the other half uses laser cutting. These cut pre-strained half dog-bone coupons are loaded under a uniaxial tension to acquire the edge cracking limit. The thinning strain is measured to calculate the edge cracking limit using a 3D digital image correlation (3D-DIC) system. Also, the pre-strain level of each coupon is precisely determined using the 3D-DIC system. The detailed experimental setup, procedure, and results are described in this article. The different behavior of edge cracking limit at different pre-strain level by adopting the laser cutting method is discussed and concluded.