Study on Microstructure and Formability of DP Steel of Lightweight Automobile

2013 ◽  
Vol 321-324 ◽  
pp. 184-187
Author(s):  
Jin Wu
Keyword(s):  
Mechanical Property ◽  
High Strength Steel ◽  
High Strength ◽  
Mathematic Model ◽  
Theoretical Research ◽  
Forming Limit ◽  
Dp Steel ◽  
Practical Usefulness ◽  
Auto Panel ◽  
Better Than

Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability 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 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.

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.

Microstructure and Mechanical Property of 22MnB5 High-Strength Steel

2013 ◽  
Vol 864-867 ◽  
pp. 644-647
Author(s):  
Ao Ran Wei ◽  
Hong Wei Liu ◽  
Jing Fan Chen
Keyword(s):  
Heat Treatment ◽  
Mechanical Property ◽  
Tensile Strength ◽  
High Strength Steel ◽  
Lath Martensite ◽  
High Strength ◽  
22Mnb5 Steel ◽  
Specific Elongation ◽  
Microstructure And Mechanical Property ◽  
Better Than

We have mental heat treatment for 22MnB5 steel with seven different experimental schemes and have mechanical property test on the seven steels. Then the microstructure and mechanical property of treated steels are studied, and the results show that 300°C is the optimum preservation temperature, at which we can get the optimum specific elongation of 22MnB5 steel. The tensile strength of steel thermal insulated at 300°C for 3 minutes is better than that of steel tempered at 300°C for 3 minutes, while as for specific elongation , the latter one is better. And we can also get homogeneous lath martensite after die quenching. The experiment lays foundations of the actual production process of hot forming.

Formability Analysis of Fukui Stretch-Drawing and Square Cup Drawing Using Strain and Stress Based Forming Limit Curves

2017 ◽  
Vol 751 ◽  
pp. 167-172 ◽  
Author(s):  
Sansot Panich ◽  
Nopparat Seemuang ◽  
Taratip Chaimongkon
Keyword(s):  
Flow Behavior ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Yield Criteria ◽  
Hardening Law ◽  
Stress Curve ◽  
Strain Paths ◽  
Cup Drawing ◽  
Better Than

In this work, the experimental and numerical analyses of Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) for Advanced High Strength Steel (AHSS) sheet, grade JAC780Y, are performed. Initially, the FLC is experimentally determined by means of the Nakazima Stretch forming test. Subsequently, the FLSC of investigated steel was plastically calculated using the experimental FLC data. Different yield criteria including Hill48, and Yld89, are applied to describe plastic flow behavior of the AHS steel and Swift hardening law is taken into account. Hereby, influences of the constitutive yield models on the numerically determined FLSCs are evaluated regarding to those results from the experimental data. The obtained stress based forming limits are affected significantly by the yield criteria. Finally, the experimental and numerical formability analyses of Fukui stretch-drawing and square cup drawing tests are studied through FLC and FLSCs. It is observed that all stress based curves can be used very well to describe material formability of the examined steel compared to the strain based FLC. The strain based FLC depend on forming history and strain paths change. In the other hand, the stress based FLC do not depend on these issue. In this study, it can be concluded that the FLSCs could predict failure more realistically and better than the strain based FLC.

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.

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.

Structure Analysis and Quality Prediction of DP Steel Engine Hood in the Process of Hot Stamping

2013 ◽  
Vol 791-793 ◽  
pp. 558-561
Author(s):  
Zhi Ping Zhang ◽  
Han Wu Liu ◽  
Tian Xiang Chen ◽  
Zhang Yi Yu
Keyword(s):  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Dp Steel ◽  
Performance Requirements ◽  
Stamping Process ◽  
Work Hardening Rate ◽  
Initial Work ◽  
Parts Manufacturing

Due to its good formability characteristics, such as high strength, high initial work hardening rate, as well as continuous yielding, thin-walled DP steel possesses great advantages of weight loss and security, and has been used to replace ordinary steel for automotive parts manufacturing by a lot of automotive industry. But along with the improvement of the performance of the strength, the high strength steels formability is worsened dramatically, and failure and fracture often occurs in its cold stamping process. So, hot stamping technology must be adopted to make the formability available. In the paper, it took the hot stamping process of DP steel engine hood for example and took DP800 as object of research. The forming limit, variation of major strain, minor strain and thickness, as well as the potential equality defects were analyzed by using eta/DYNAFORM software. The research results show that duplex steel plate can meet the performance requirements of car engine dumping plank forming, which offers theory basis for the production of similar parts.

Variable Amplitude Corrosion Fatigue Tests on a High Strength Jack-Up Steel

2002 ◽  
Author(s):  
W. D. Dover ◽  
A. Stacey ◽  
N. Tantbirojn ◽  
F. P. Brennan
Keyword(s):  
Cathodic Protection ◽  
High Strength Steel ◽  
Random Sequence ◽  
High Strength ◽  
Fatigue Tests ◽  
Tubular Joint ◽  
Steel Joints ◽  
Jack Up ◽  
Growth Evolution ◽  
Better Than

A series of fatigue tests were conducted on T-butt-welded specimens made from high strength (SE702) jack-up steel. Fatigue tests were conducted using a pseudo-random sequence (JOSH) designed to give typical jack-up loading at two levels of cathodic protection. The results are presented in terms of fatigue life and crack growth evolution. The results for the T-butt joints were compared to tubular joint fatigue test data obtained with conventional fixed platform steels (BS4360 Gr50D) and the same high strength steel (SE702). The study indicated that for high strength steel joints with relatively short fatigue lives the influence of the cathodic protection level is quite small and the fatigue resistance is slightly better than that of joints fabricated from conventional structural steels such as BS4360 50D.

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