Material anisotropy and trimming method effects on total elongation in DP500 sheet steel

Abstract The objective of this study is to determine the influence of material anisotropy and trimming method on the total elongation of the trimmed edge of DP500 sheet steel. For various orientations, experimental analysis is carried out on rectangular shaped tensile test specimens featuring a polished edge on one side and a trimmed edge on the other side. It is shown that the total elongation in DP500 steel exhibits significant sensitivity to (1) specimen orientation with respect to rolling direction, and (2) trimming method employed. In particular, difference in total elongation between longitudinal and transverse orientations become more pronounced with increasing trim clearance for conventionally trimmed samples. Total elongation anisotropy, however, can be significant even at small trim clearances and when sheared surface of the blank has relatively good quality without the burr which is the case for samples trimmed by the technology with offal support and dulled upper trim edge. The observations provided herein may be instrumental in contributing to meaningful explanations for unexpected edge cracking problems observed in some DP500 stamping cases. Recommendations for manufacturing best practices are offered.

[1]  X. M. Chen,et al.  Prediction of Stretch Flangeability Limits of Advanced High Strength Steels using the Hole Expansion Test , 2007 .

[2]  R. G. Davies.  Edge cracking in high strength steels , 1983 .

[3]  Sergey Fedorovich Golovashchenko,et al.  A study on trimming of aluminum autobody sheet and development of a new robust process eliminating burrs and slivers , 2006 .

[4]  M. S. Rashid.  GM 980X-A Unique High Strength Sheet Steel with Superior Formability , 1976 .

[5]  C. J. Tyne,et al.  Failure During Sheared Edge Stretching , 2008, Journal of Materials Engineering and Performance.

[6]  Sergey Fedorovich Golovashchenko,et al.  Trimming of Advanced High Strength Steels , 2005 .

[7]  Daw-Kwei Leu,et al.  Finite-element simulation of hole-flanging process of circular sheets of anisotropic materials , 1996 .

[8]  R. G. Davies.  The deformation behavior of a vanadium-strengthened dual phase steel , 1978 .

[9]  S. Sriram,et al.  Sheared Edge Characterization of Steel Products used for Closure Panel Applications , 2006 .

[10]  K. S. Raghavan,et al.  Recent Progress in the Development of Forming Limit Curves for Automotive Sheet Steels , 1992 .

[11]  K. S. Choi,et al.  Predicting failure modes and ductility of dual phase steels using plastic strain localization , 2009 .

[12]  A. Luo,et al.  The evolution of technology for materials processing over the last 50 years: The automotive example , 2007 .

[13]  Sergey Fedorovich Golovashchenko,et al.  Analysis of Trimming Processes for Advanced High Strength Steels , 2008 .

[14]  R. G. Davies.  Influence of martensite composition and content on the properties of dual phase steels , 1978 .

[15]  Sergey Fedorovich Golovashchenko,et al.  Analysis of Trimming of Aluminum Closure Panels , 2007 .