Springback Behavior of Advanced High Strength Steel (AHSS) CP800

2013 ◽  
Vol 820 ◽  
pp. 45-49 ◽  
Author(s):  
Mei Zhang ◽  
Jun Zhang ◽  
Yu Xiang Ning ◽  
Tao Wang ◽  
Zi Wan
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Test Results ◽  
Complex Phase ◽  
Advanced High Strength Steels ◽  
Test Conditions ◽  
Hsla Steels ◽  
Blank Holding Force ◽  
Microalloying Elements ◽  
Springback Behavior

800MPa grade Advanced High Strength Steels (AHSS), Complex Phase steel CP800, containing microalloying elements, are chosen to test the stamping properties in different test conditions and compared with traditional high strength low alloy (HSLA) steels HSLA S700MC. Tensile test, and HAT shape stamping test are taken to investigate the properties of the materials. Test results indicate that the studied 800MPa grade AHSS shows a better strength ductility balance compared with the reference HSLA steels. Under the same HAT shape springback stamping condition, HSLA steels S700MC always show the largest springback deformation among the investigated steels. While springback angles of all the AHSS studied are markedly smaller than that of steel S700MC. Among the 3 kinds of AHSS researched, CP800T always show the largest springback deformation. Domestic steel CP800 and imported CP800S show much smaller springback deformation respectively. In BHF of 100KN condition, springback deformation of 3 kinds of AHSS reaches the top value among all the BHF conditions. However, steel CP800 indicates an outstanding springback restrain trend in blank holding force (BHF) further increasing attempt. Thus, springback behavior can be restricted obviously by using a larger blank holding force (BHF) in steel CP800 stamping cases.

Forming Performance of 800MPa Grade Advanced High Strength Steels

2013 ◽  
Vol 455 ◽  
pp. 173-178 ◽  
Author(s):  
Mei Zhang ◽  
Yu Xiang Ning ◽  
Jun Zhang ◽  
Zi Wan ◽  
Tao Wang
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Expansion Ratio ◽  
Hole Expansion ◽  
Advanced High Strength Steels ◽  
Hsla Steels ◽  
Blank Holding Force ◽  
Hole Expansion Ratio ◽  
Test Hole ◽  
Springback Behavior

800MPa grade Advanced High Strength Steels (AHSS), including Complex Phase steel CP800 and Ferrite-Bainite steel FB800, were chosen to test the forming performance in different test conditions and compared with the reference traditional high strength low alloy (HSLA) steels HR700LA. Tensile test, hole expansion (HE) test, and HAT shape stamping test were taken to investigate the forming performance of the materials. Test results indicated that the studied 800MPa grade AHSS showed a better strength ductility balance compared with the reference steel. Among all the steels researched, FB800 showed the best hole expansion ratio (HER), and CP800 the worst. Springback angles of AHSS after HAT shape stamping tests were markedly smaller than those of HR700LA steels, though the springback angles of HR700LA decreased continuously with blank holding force (BHF) increasing. Steel FB800, CP800S and CP800B had much better shape stability compared with steels HR700LA. AHSS showed much smaller springback behavior under the same stamping condition, especially for steels CP800-B, FB800-2 and FB800-1. When increasing the BHF to 100KN, AHSS showed the largest springback deformation. Among the three kinds of CP800 steels researched, steel CP800-B indicated outstanding springback restrain trend in BHF further increasing attempt. So, springback behavior could be restricted obviously by using a larger BHF in AHSS CP800B forming operations.

Critical Assessment of Bainite Models for Advanced High Strength Steels

2011 ◽  
Vol 172-174 ◽  
pp. 1183-1188 ◽  
Author(s):  
Fateh Fazeli ◽  
Tao Jia ◽  
Matthias Militzer
Keyword(s):  
Bainitic Ferrite ◽  
High Strength Steels ◽  
High Strength ◽  
Transformation Model ◽  
Complex Phase ◽  
Simultaneous Formation ◽  
Transformation Induced Plasticity ◽  
Advanced High Strength Steels ◽  
Formation Kinetics ◽  
Robust Processing

Bainite is an essential constituent in the microstructure of many advanced high strength steels, e.g. ferrite-bainite dual-phase, transformation induced-plasticity (TRIP) and complex phase (CP) steels. A complex thermo-mechanical processing is employed in industry such that following ferrite formation a desired fraction of bainite can be obtained during austenite decomposition. In order to evaluate robust processing routes it would be very useful to have a bainite transformation model with predictive capabilities. In this work a transformation start criterion for bainite is proposed by defining a critical driving pressure concept. Subsequent bainite formation kinetics from a mixture of ferrite-austenite is described using phenomenological modelling methodologies. In particular, the predictive capabilities of two approaches will be critically discussed, i.e. (i) the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model in conjunction with Rios treatment of the additivity rule and (ii) a nucleation-growth based model that describes simultaneous formation of bainitic ferrite and carbides. Using experimental transformation data for TRIP and CP steels, status and limitations of these models will be delineated.

Innovative Geometric Redesign of Safety Footwear Components Using a Reverse Engineering Approach

2013 ◽  
Author(s):  
Sérgio L. Costa ◽  
Joel V. Silva ◽  
Nuno Peixinho ◽  
João P. Mendonça
Keyword(s):  
Reverse Engineering ◽  
High Strength Steels ◽  
High Strength ◽  
Test Results ◽  
Element Analysis ◽  
Static Compression ◽  
Advanced High Strength Steels ◽  
Engineering Approach ◽  
Different Thickness ◽  
Quasi Static Compression

The normative behavior of innovative toe cap models for safety footwear with different thickness ranges and materials, including Advanced High Strength Steels (AHSS), was investigated by means of the quasi-static compression test. The main purpose of this work was to confirm the solution potential of a new geometric redesign model, from a reverse engineering approach, that maximizes the potential of energy absorption. The investigation was performed with two dissimilar and evolutionary geometric models, and several properties correlations such as: stiffness, thickness range and material properties. From a Finite Element Analysis and experimental test results of toe cap prototypes, it was found that the geometric factor had significant influence on the balance of the structural stiffness with thickness reduction. The study of the elastic deformation and the springback effect of different models, allows pointing an improved weight saving of a new toe cap component.

Influence of Microalloying Elements Ti and Nb on Recrystallization during Annealing of Advanced High-Strength Steels

2016 ◽  
Vol 879 ◽  
pp. 217-223 ◽  
Author(s):  
Marion Bellavoine ◽  
Myriam Dumont ◽  
Josée Drillet ◽  
Philippe Maugis ◽  
Véronique Hebert
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Solute Drag ◽  
Dual Phase ◽  
Comparative Efficiency ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
Cold Rolled ◽  
Microalloying Elements ◽  
Predominant Effect

Microalloying elements Ti and Nb are commonly added to high-strength Dual Phase steels as they can provide efficient means for additional strengthening due to grain refinement and precipitation strengthening mechanisms. In the form of solute elements or as fine carbonitride precipitates, Ti and Nb are also expected to have a significant effect on the microstructural changes during annealing and especially on recrystallization kinetics. The present work investigates the influence of microalloying elements Ti and Nb on recrystallization in various cold-rolled Dual Phase steel grades with the same initial microstructure but different microalloying contents. Using complementary experimental and modeling approaches makes it possible to give some clarifications regarding both the nature of this effect and the comparative efficiency of Ti and Nb on delaying recrystallization. It is shown that niobium is the most efficient micro-alloying element to impede recrystallization and that the predominant effect is solute drag.

scholarly journals Study of Diffusible Behavior of Hydrogen in First Generation Advanced High Strength Steels

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 782
Author(s):  
Dwaipayan Mallick ◽  
Nicolas Mary ◽  
V. S. Raja ◽  
Bernard Normand
Keyword(s):  
Diffusion Coefficients ◽  
First Generation ◽  
High Strength Steels ◽  
High Strength ◽  
Specimen Thickness ◽  
Dual Phase ◽  
Complex Phase ◽  
Advanced High Strength Steels ◽  
Permeation Studies ◽  
Dp Steels

This study deals with microstructural influence on the H permeation behavior of Dual-Phase (DP) and Complex Phase (CP) steels using electrochemical permeation studies. The H diffusion coefficients in DP steels (DP800: 1.65 × 10−10 m2·s−1, DP1000: 1.58 × 10−10 m2·s−1) are half of that found in CP steels (3.07 × 10−10 m2·s−1).The banded microstructure along the specimen thickness and higher C content of the DP led to high H diffusivity of DP steels. The lower total H concentration along with a higher fraction of H was present in the stronger traps in CP steels suggest a better HE resistance of this steel. The H distribution in the specimens was non-uniform, with a higher H concentration speculated near the charging surface.

Microalloying of Cold-Formable Multi Phase Steel Grades

2005 ◽  
Vol 500-501 ◽  
pp. 97-114 ◽  
Author(s):  
Wolfgang Bleck ◽  
Kriangyut Phiu-On
Keyword(s):  
Precipitation Hardening ◽  
High Strength Steels ◽  
High Strength ◽  
Chemical Compositions ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
High Manganese Steels ◽  
Microalloying Elements ◽  
Multi Phase ◽  
Manganese Steels

Microalloying elements like Al, B, Nb, Ti ,V can be used to optimise the microstructure evolution and the mechanical properties of advanced high strength steels (AHSS). Microalloying elements are characterised by small additions < 0.1 mass% and their ability to form carbides or nitrides. They can increase strength by grain refinement and precipitation hardening, retard or accelerate transformations and affect the diffusion kinetics as well as the stacking fault energy. Thus, by their addition the AHSS with their high requirements to process control can be adopted to existing processing lines. Different combinations of microstructural phases and different chemical compositions have been investigated for AHSS in order to combine high strength with excellent formability. The recently developed high manganese steels further improve the formability due to their austenitic microstructure and inherent phase transformations during forming.

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