Effect of Counter Punch Pressure on Springback of High Strength Steel Sheet

2014 ◽  
Vol 939 ◽  
pp. 305-312 ◽  
Author(s):  
Komgrit Lawanwong ◽  
Hiroshi Hamasaki ◽  
Ryutaro Hino ◽  
Fusahito Yoshida
Keyword(s):  
Final Stage ◽  
Steel Sheet ◽  
Fe Simulation ◽  
Kinematic Hardening ◽  
High Strength ◽  
Dual Phase ◽  
Clamping Force ◽  
Bending Process ◽  
A New Technique ◽  
Punch Pressure

To reduce springback in U-bending the present paper proposes a new technique where the bottom of a U-bent part is clamped between a punch and a counter-punch during bending and it is pushed up with the counter punch at the final stage. The effect of counter punch pressure, both in sheet clamping and bottoming, was investigated by performing experiments on dual phase 590MPa and TRIP 780MPa HSS sheets. From the experiment, an appropriate combination of the clamping force and the final pushing-up force was found where springback was reduced to almost zero. To investigate the mechanism of the reduction of springback in the above three-step U-bending process, FE simulation of the bending with PAM-STAMP 2G was also conducted where the advanced kinematic hardening Yoshida-Uemori model was employed.

USS DUAL PHASE 80

Alloy Digest ◽  
1978 ◽  
Vol 27 (12) ◽  
Keyword(s):  
United States ◽  
Corrosion Resistance ◽  
Yield Strength ◽  
Work Hardening ◽  
Steel Sheet ◽  
High Strength ◽  
Heat Treating ◽  
Dual Phase ◽  
United States Steel Corporation ◽  
Heavy Construction

Abstract USS Dual Phase 80 is a high-strength steel sheet which has a dual phase structure of martensite and ferrite. It provides all the benefits of higher strength with little sacrifice in ductility, formability or weldability. Dual Phase 80 gains strength as it is formed through rapid work hardening of its unique microstructure; in fact, it increases from its delivered yield strength of 50,000 psi up to 80,000 psi (or more) in forming. Its final strength depends on the amount of forming. Its many applications include automotive vehicles, farm equipment and heavy construction equipment. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-352. Producer or source: United States Steel Corporation.

Work-Hardening Behavior of Cold Rolled Interstitial-Free Steel Sheet and Dual Phase High Strength Steel Sheets Subjected to Two-Stage, Coaxial and Non-Coaxial Tension/Compression

2015 ◽  
Vol 651-653 ◽  
pp. 83-88 ◽  
Author(s):  
Satoshi Shirakami ◽  
Shigeru Yonemura ◽  
Tohru Yoshida ◽  
Noriyuki Suzuki ◽  
Toshihiko Kuwabara
Keyword(s):  
Work Hardening ◽  
Steel Sheet ◽  
High Strength ◽  
Dual Phase ◽  
Interstitial Free ◽  
If Steel ◽  
Two Stage ◽  
Work Hardening Behavior ◽  
Hardening Behavior ◽  
Cold Rolled

In-plane tension/compression tests of a cold rolled interstitial-free (IF) steel and sheet a 980MPa dual phase high strength steel sheet (980DP) were carried out to investigate the work-hardening behavior under two-stage loading paths. The two-stage loading paths consist of the uniaxial tension/compression for the rolling direction (RD) followed by unloading and subsequent uniaxial tension/compression in the 0°, 45° and 90° directions from the first loading direction (0°-, 45°- and 90°-loading). The work hardening behavior in the second loading was different between the 980DP and the IF steel. It was found that the work hardening behaviors were significantly affected by the inner product of the strain rate mode tensors for the first and second loading and that the effect of the deformation mode (tension/compression) was small.

Increasing the Dimensional Accuracy of U-Bend Product of High Strength Steel Sheets by Pressure Pad

2019 ◽  
Vol 962 ◽  
pp. 159-166
Author(s):  
Pongsakorn Leetrakul ◽  
Komgrit Lawanwong
Keyword(s):  
High Strength Steel ◽  
Steel Sheet ◽  
Kinematic Hardening ◽  
Bending Moment ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Steel Sheets ◽  
New Process ◽  
Springback Reduction ◽  
Springback Behavior

To reduce springback in U-shape of high strength steel sheet, the present paper proposes a new process parameter in U-bending technique. This paper aims to present the effect of clearance between die and pressure pad on springback behavior. The process in this work consists of four steps: (1) clamping of a sheet between a punch and a pressure pad, (2) bending with constant clamping force, (3) pushing-up at bottom of the part by using the pressure pad, and (4) final release tool. From the experimental results, decreasing of bending moment by bottom pushing-up resulted in the springback reduction. An appropriate of the clearance between die and pressure pad combined with bottom pushing-up force can be reduced springback. Our results suggested that the Y-U model, an advanced kinematic hardening, is essential for accurate numerical simulation of springback behavior.

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