Forming Limit of High-Strength Steel Sheet in Stretch Forming Process under Strain Path Changes

2012 ◽  
Vol 53 (621) ◽  
pp. 891-895
Author(s):  
Ryutaro HINO
Keyword(s):  
High Strength Steel ◽  
Strain Path ◽  
Steel Sheet ◽  
High Strength ◽  
Forming Limit ◽  
Stretch Forming ◽  
Forming Process ◽  
Strain Path Changes

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.

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

Establishment and Application of Forming Limit Diagram of Multi-Gauge Laser Tailor-Welded Blanks

2010 ◽  
Vol 97-101 ◽  
pp. 420-425
Author(s):  
Wei Chen ◽  
S. Cheng ◽  
Y. Ding ◽  
Y.Q. Guo ◽  
L. Xue
Keyword(s):  
High Strength Steel ◽  
Research Method ◽  
Forming Limit Diagram ◽  
High Strength ◽  
Failure Criteria ◽  
Limit Strain ◽  
Measuring System ◽  
Forming Limit ◽  
Forming Process ◽  
Tailor Welded Blanks

The method for establishing the forming limit diagram (FLD) of multi-gauge high strength steel laser tailor-welded blanks (LTWB) is introduced based on analyzing the failure mechanism of multi-gauge LTWB. The Nakazima test is performed to generate the limit strain of multi-gauge high strength steel LTWB. By means of the ARGUS strain measuring system, the limit strain is measured and the FLD of LTWB is plotted subsequently. The FLD established by the Nakazima test is introduced into the FEA forming process as the failure criteria. Compared with the predicted result of the FLD of thinner metal, better correlation between the simulation and experimental results is indicated by adopting the FLD of LTWB as the necking criteria, which also reveals the validity and practicability of the FLD research method for multi-gauge high strength steel LTWB.

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