scholarly journals Development of Measurement Equipment and Experimental and Numerical Simulation Studies for Warm Forming Limits of High-Strength Steel

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2373
Author(s):  
Qiang Yu ◽  
Jin Liang ◽  
Qiu Li ◽  
Chengyao Li
Keyword(s):  
Test Temperature ◽  
High Strength Steel ◽  
Digital Simulation ◽  
High Strength ◽  
Warm Forming ◽  
Test Method ◽  
Forming Limit ◽  
Measurement Equipment ◽  
Forming Limits ◽  
Bulging Test

This paper describes the research and development of a set of measurement equipment for the warm forming limits of high-strength steel based on the Nakazima bulging test method and the digital image correlation method. The equipment could provide an argon shield and a water-cooling atmosphere, as well as two heating options: heating the specimen, dies, and environment to the test temperature simultaneously or heating the specimen to the test temperature at a higher speed than that for the dies and environment. The equipment was applied to measure the forming limit curves for high-strength DP600 steel at room temperature and at the temperature of 300 °C to verify its performance. The DYNAFORM software was then applied for the digital simulation of the bulging test method. A new limit-strain-fitting method was proposed to eliminate the impact of the distorted grid on the digital simulation process. The change trend of the forming limit curve acquired in the test had sound consistency with the test results.

Forming Limits of Several High-Strength Steel Sheets under Proportional/Non-Proportional Deformation Paths

2014 ◽  
Vol 939 ◽  
pp. 260-265 ◽  
Author(s):  
Ryutaro Hino ◽  
Satoki Yasuhara ◽  
Yutaka Fujii ◽  
Atsushi Hirahara ◽  
Fusahito Yoshida
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Experimental Results ◽  
Forming Limit ◽  
Type Analysis ◽  
Forming Limits ◽  
Steel Sheets ◽  
Path Dependent ◽  
Forming Limit Curves ◽  
Good Agreement

Forming limits of several high-strength steel (HSS) sheets under non-proportional deformation paths were examined experimentally and predicted analytically. Forming limit curves (FLCs) for 590MPa, 780MPa and 980MPa grade HSS sheets were obtained by performing stretch forming tests under proportional deformation and two types of non-proportional deformation. The experimental results showed strong path-dependent characteristics of FLCs of HSS sheets. Forming limits of equi-biaxially prestrained HSS sheets became markedly lower compared to the original FLCs under proportional deformation, while forming limits of uniaxially prestrained HSS sheets became partially higher than the original FLCs. It was confirmed that Marciniak-Kuczyński type analysis gave reasonably good predictions of forming limits under non-proportional deformation paths. Especially forming limit predictions of equi-biaxially-prestrained sheets showed good agreement with the corresponding experimental results.

The Microstructure and Formability Study on DP Steel of Lightweight Automobile

2011 ◽  
Vol 704-705 ◽  
pp. 1465-1472
Author(s):  
Jin Wu ◽  
Da Sen Bi ◽  
Liang Chu ◽  
Jian Zhang ◽  
Yun Tao Li
Keyword(s):  
Mechanical Property ◽  
Work Hardening ◽  
High Strength Steel ◽  
High Strength ◽  
Mathematic Model ◽  
Theoretical Research ◽  
Forming Limit ◽  
Strain Hardening Exponent ◽  
Dp Steel ◽  
Better Than

Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability, baked-hardening and work hardening properties of high strength steel DP450 are studied by experiments, and compared with those of steel MS6000.And theoretical research on predicting the forming limit of steel DP450 by the NADDRG model. The established mathematic model for relativity is of practical usefulness. Experimental results reveal that the yield strength of steel DP450 is about 7.2% lower than the MS6000,and the break strength increases by 18.9%,while the elongation increases by 19%.The strain hardening exponent of steel DP450 are superior to those of MS6000.The results show that mechanical property of high strength steel DP450 is better than that of MS6000,while forming ability of DP450 is not lower than that of MS6000.And baked-hardening and work hardening properties of steel DP450 are better than those of MS6000.The steel sheet DP450 owned a good forming ability.

Effect of Stress Relaxation on Springback of Steel Sheet in Warm Forming

2016 ◽  
Vol 725 ◽  
pp. 671-676 ◽  
Author(s):  
Naoko Saito ◽  
Mitsugi Fukahori ◽  
Daisuke Hisano ◽  
Hiroshi Hamasaki ◽  
Fusahito Yoshida
Keyword(s):  
Stress Relaxation ◽  
High Strength Steel ◽  
Room Temperature ◽  
Steel Sheet ◽  
Elevated Temperatures ◽  
High Strength ◽  
Warm Forming ◽  
Sheet Metals ◽  
Stress Relaxation Behavior ◽  
Increasing Temperature

Springback of a high strength steel (HSS) sheet of 980 MPa grade was investigated at elevated temperatures ranging from room temperature to 973 K. From U-and V-bending experiments it was found that springback was decreased with increasing temperature at temperatures of above 573 K. Furthermore, springback was decreased with punch-holding time because of stress relaxation. In this work, the stress relaxation behavior of the steel was experimentally measured. By using an elasto-vicoplasticity model, the stress relaxation was described, and its effect on the springback of sheet metals in warm forming was discussed theoretically.

Forming Limit Extension of High-Strength Steels in Bending Processes

2014 ◽  
Vol 611-612 ◽  
pp. 1110-1115 ◽  
Author(s):  
Mohamed El Budamusi ◽  
Andres Weinrich ◽  
Chrstioph Becker ◽  
Sami Chatti ◽  
A. Erman Tekkaya
Keyword(s):  
Hydrostatic Pressure ◽  
Metal Forming ◽  
Fem Simulation ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limits ◽  
Air Bending ◽  
Forming Technology ◽  
Bending Process

Bending is a commonly used forming technology in metal forming. The occurring springback and low forming limits of high-strength steels especially during air bending are the main disadvantages. In this paper, the conventional air bending process is applied with a hydrostatic pressure in the bending zone. This was done using an elastomer tool. The advantage of this method is that the flexibility of air bending is maintained by reducing the springback while the forming limits are extended. Furthermore, different geometries for the elastomer tool were investigated by means of a FEM simulation. The investigation leads to a reduction of the process forces by minimizing the springback and to an extension of the forming limits.

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.

Effect of Strain Paths on Formability Evaluation of TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 214-219 ◽  
Author(s):  
David Gutiérrez ◽  
A. Lara ◽  
Daniel Casellas ◽  
Jose Manuel Prado
Keyword(s):  
Strain Path ◽  
High Strength Steels ◽  
High Strength ◽  
Test Method ◽  
Forming Limit ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Strain Paths ◽  
Analysis System

The Forming Limit Diagrams (FLD) are widely used in the formability analysis of sheet metal to determine the maximum strain, which gives the Forming Limit Curve (FLC). It is well known that these curves depend on the strain path during forming and hence on the test method used to calculate them. In this paper, different stretching tests such as the Nakajima and the Marciniak tests were performed, with different sample geometries to obtain points in different areas of the FLD. An optical analysis system was used, which allows following the strain path during the test. The increasing use of advanced high-strength steels (AHSS) has created an interest in determining the mechanical properties of these materials. In this work, FLCs for a TRIP steel were determined using Nakajima and Marciniak tests, which revealed different strain paths depending on the type of test. Determination of the FLCs was carried out following the mathematical calculations indicated in the ISO 12004 standard and was also compared with an alternative mathematical method, which showed different FLCs. Finally, the tests were verified by comparing the strain paths of the Nakajima and Marciniak tests with a well-known mild steel.

scholarly journals Temperature-dependent yield criterion for high strength steel sheets under warm-forming conditions

2015 ◽  
Vol 21 ◽  
pp. 07008 ◽  
Author(s):  
Zhengyang Cai ◽  
Keshan Diao ◽  
Xiangdong Wu ◽  
Min Wan ◽  
Cheng Cheng
Keyword(s):  
High Strength Steel ◽  
Yield Criterion ◽  
High Strength ◽  
Warm Forming ◽  
Temperature Dependent ◽  
Steel Sheets
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