This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Development of Shear Fracture Criterion for Dual-Phase Steel Stamping
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 20, 2009 by SAE International in United States
Annotation ability available
Forming Limit Diagrams (FLD) have been widely and successfully used in sheet metal stamping as a failure criterion to detect localized necking, which is the most common failure mechanism for conventional steels during forming. However, recent experience from stamping Dual-Phase steels found that, under certain circumstances such as stretching-bend over a small die radius, the sheet metal fails earlier than that predicted by the FLD based on the initiation of a localized neck. It appears that a different failure mechanism and mode are in effect, commonly referred to as “shear fracture” in the sheet metal stamping community. In this paper, experimental and numerical analysis is used to investigate the shear fracture mechanism. Numerical models are established for a stretch-bend test on DP780 steel with a wide range of bend radii for various failure modes. The occurrences of shear fracture are identified by correlating numerical simulation results with test data. The study suggest that the shear fracture is due to the failure of martensitic grains at micro-level when certain criteria are reached, and the macroscopic failure mode during forming operations is viewed as the competition between localized necking and the shear fracture, whichever criterion is satisfied first. Same studies are also repeated for a HSLA grade steel, which consists entirely of ferritic phases, to emphasize the critical role played by martensitic grains in the shear fracture development. The relevance of the shear fracture criterion to industrial stamping is discussed.
|Journal Article||Analysis of Trimming Processes for Advanced High Strength Steels|
|Technical Paper||Study of Incremental Bending Test on Aluminum Sheets|
|Technical Paper||Ultimate Strength and Failure Mode of Spot Welds in High Strength Steels|
CitationZeng, D., Xia, Z., Shih, H., and Shi, M., "Development of Shear Fracture Criterion for Dual-Phase Steel Stamping," SAE Technical Paper 2009-01-1172, 2009, https://doi.org/10.4271/2009-01-1172.
- Charpentier P. L. (1974) “Influence of punch curvature on the stretching limits of sheet steel”, Metallurgical Transactions A, 6A, 1665–1669.
- Ghosh A. and Hecker S. (1974) “Stretch limits in sheet metals: in-plane versus out-of-plane deformation”, Metallurgical Transactions, 5, 2161–2164.
- Ragab A. R. and Baudelet B. (1982) “Forming limit curves: out-of-plane and in-plane stretching”, J. Mech. Working Tech., 6, 267–276.
- Shi M. F. and Gerdeen J. C. “Effect of strain gradient and curvature on forming limit diagrams for anisotropic sheets”, J. Mater. Shaping Technol., 9, 1991, 253–268.
- Tharrett M. R. and Stoughton T. B. “Stretch-bend forming limits of 1008 AK steel”, SAE2003-01-1157.
- Xia Z. and Zeng, D. “Sheet metal forming limit under stretch-bending”, MSEC2008-72032.
- Sadagopan, S. Wong, C. Huang, M. and Yan, B. “Stretch Bendability of Advanced High Strength Steels”, SAE2003-01-1151.
- Shih H. C. and Shi, M. “Experimental study on shear fracture of advanced high strength steels”, MSEC/ICMP2008-72046.
- Walp, M. Wurm, A. Siekirk J. and Desai, A. “Shear fracture in advanced high strength steels”, SAE 2006-01-1433.
- Hudgins, A. Matlock, D. Speer, J. Fekete J. and Walp, M. “The susceptibility to shear fracture in bending of advanced high strength sheet steels”, MS&T 2007, p 145–157.
- Erdogan M. and Tekeli, S. “The effect of martensite particle size on tensile fracture of surface carburized AISI 8620 steel with dual phase core microstructure”, Material and Design, Vol. 23, 2002, p 597–604.