108 Forming limit in stretch flanging of high strength steel sheet under various types of deformation

2012 ◽  
Vol 2012.50 (0) ◽  
pp. 10801-10802
Author(s):  
Yutaka FUJII ◽  
Hideaki TAKAOKA ◽  
Ryutaro HINO ◽  
Fusahito YOSHIDA ◽  
Hiroyuki ISHII ◽  
...  
Keyword(s):  
High Strength Steel ◽  
Steel Sheet ◽  
High Strength ◽  
Forming Limit ◽  
Stretch Flanging

Forming Limit Analyses of 590 MPa High Strength Steel Sheet Using Differential Work Hardening Model

2014 ◽  
Vol 622-623 ◽  
pp. 353-358 ◽  
Author(s):  
Tomoyuki Hakoyama ◽  
Toshihiko Kuwabara
Keyword(s):  
Plastic Strain ◽  
Work Hardening ◽  
High Strength Steel ◽  
Steel Sheet ◽  
Testing Machine ◽  
High Strength ◽  
Plastic Work ◽  
Forming Limit ◽  
Plastic Deformation Behavior ◽  
Tubular Specimens

A servo-controlled tension-internal pressure testing machine with an optical 3D deformation analysis system (ARAMIS®, GOM) was used to measure the multiaxial plastic deformation behavior of a 590MPa high strength steel sheet for a range of strain from initial yield to fracture. Tubular specimens were fabricated from the sheet sample by roller bending and laser welding. Many linear stress paths in the first quadrant of stress space were applied to the tubular specimens to measure the forming limit curve (FLC) and forming limit stress curve (FLSC), in addition to the contours of plastic work and the directions of plastic strain rates. It was found that the shapes of the measured work contours changed with the increase of work hardening (plastic work). The observed differential work hardening (DWH) behavior was approximated by changing the material parameters and the exponent of the Yld2000-2d yield function (Barlat et al, 2003) as a function of the equivalent plastic strain. The FLC and FLSC calculated using the Marciniak-Kuczyński-type (M-K) approach with the DWH model were in good agreement with the measurement.

Influence of Pre-Stretching Levels on the Forming Limit Strain and Stress Curves of High Strength Steel Sheet

2019 ◽  
Vol 798 ◽  
pp. 25-31
Author(s):  
Korkiat Laokor ◽  
Bunyong Chongthairungruang ◽  
Sansot Panich
Keyword(s):  
High Strength Steel ◽  
Strain Path ◽  
Steel Sheet ◽  
Biaxial Loading ◽  
Yield Criterion ◽  
Flow Behavior ◽  
High Strength ◽  
Forming Limit ◽  
Linear Strain ◽  
Non Linear

In this work, Forming Limit Curves (FLCs) of the conventional and pre-stretched High Strength Steel (HSS) sheet grade 440 (SCGA440-45) were investigated. The conventional forming limit curve was experimentally determined by using the Nakajima stretching test. Subsequently, the non-linear strain path FLCs were precisely developed through the Nakajima stretching test after the specimens were pre-stretched in biaxial direction up to several levels on the Marciniak In-plane stretching test. The gained non-linear strain path FLCs were compared with the conventional FLC.Additionally, the experimental Forming Limit Stress Curve (FLSCs) were calculated using the experimental FLC and non-linear strain path FLCs data from investigated steel sheet. The yield criterion Hill’48 was employed in combination with the Swift strain hardening law to describe anisotropic deformation and plastic flow behavior of the HSS sheet, respectively. Hereby, the influence of pre-stretching levels on the experimentally determined the FLCs and FLSCs were examined. The results prove a significant influence of the pre-stretching levels on the both FLCs and FLSCs of the investigated HSS sheet. For a low pre-stretching in biaxial loading the FLCs demonstrated a reduced formability and the FLSCs exhibited the limited stress levels depending on the experimental FLC data.

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