Advances in Constitutive Modeling of Plasticity for Forming Applications

2016 ◽  
Vol 725 ◽  
pp. 3-14 ◽  
Author(s):  
Frédéric Barlat ◽  
Youngung Jeong ◽  
Jin Jin Ha ◽  
Carlos Tomé ◽  
Myoung Gyu Lee ◽  
...  
Keyword(s):  
Constitutive Models ◽  
High Strength Steels ◽  
Computation Time ◽  
High Strength ◽  
Industrial Applications ◽  
Dislocation Dynamics ◽  
Forming Process ◽  
Advanced High Strength Steels ◽  
Process Simulations ◽  
Multi Phase

A succinct description of advanced constitutive models for applications to forming process simulations is provided. These models are continuum-based because they are more efficient in terms of computation time than microstructure–based models. However, they are so–called advanced because they are considered in many scientific studies but rather scarcely used in industrial applications. In addition, the relationship between these continuum constitutive models and multi-scale approaches based on crystal plasticity, dislocation dynamics and mechanics of multi-phase materials, such as advanced high strength steels, is substantiated.

Pulsed LASER-(Micro)TIG Welding of Automotive Dissimilar Zn-Coated Advanced High Strength Steels Thin Sheets in Overlap Configuration

2016 ◽  
Vol 1138 ◽  
pp. 147-152
Author(s):  
Aurel Valentin Bîrdeanu
Keyword(s):  
High Performance ◽  
Pulsed Laser ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Industrial Applications ◽  
Cost Ratio ◽  
Hybrid Welding ◽  
Thin Sheets ◽  
Advanced High Strength Steels

The development and implementation into a high number of industrial applications of materials categorized as (Advanced) High Strength Steels (AHSS) due to their high performance per cost ratio is more and more present and this trend is also combined with the development and implementation of new joining technologies and processes, including laser-arc hybrid processes.The paper presents the results of applying Pulsed LASER-(micro)TIG hybrid welding process, for realizing overlap joints for Zn-coated (A)HSS materials in dissimilar configurations, joints that were presented as designed based on UltraLight Steel Auto Body (ULSAB) principles.The influence of main hybrid welding process parameters was investigated in order to establish if one can obtain joints with high values for the shear strength resistance for some of the actually used dissimilar steel combinations based on designs applied throughout ULSAB project and the autos built following these principles.

Experimental Study on Galling Behavior of Advanced High Strength Steel in Sheet Metal Forming

2012 ◽  
Vol 502 ◽  
pp. 36-40
Author(s):  
Ying Ke Hou ◽  
Shu Hui Li ◽  
Yi Xi Zhao ◽  
Zhong Qi Yu
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Sheet Material ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Process ◽  
Advanced High Strength Steels ◽  
Sheet Materials ◽  
Materials Used

Galling is a known failure mechanism in many sheet metal forming processes. It limits the lifetime of tools and the quality of the products is affected. In this study, U-channel stamping experiments are performed to investigate the galling behavior of the advanced high strength steels in sheet metal forming . The sheet materials used in the tests are DP590 and DP780. In addition to the DP steels, the mild steel B170P1 is tested as a reference material in this study. Experimental results indicate that galling problem becomes severe in the forming process and the galling tendency can be divided into three different stages. The results also show that sheet material and tool hardness have crucial effects on galling performance in the forming of advanced high strength steels. In this study, DP780 results in the most heaviest galling among the three types of sheet materials. Galling performance are improved with increased hardness of the forming tool.

Die Wear and Coating Galling in Stamping Advanced High Strength Steels

2011 ◽  
Author(s):  
Hua-Chu Shih ◽  
Ming F. Shi
Keyword(s):  
Zinc Coating ◽  
High Strength Steels ◽  
High Strength ◽  
Reactive Diffusion ◽  
Process Variables ◽  
Forming Process ◽  
Typical Application ◽  
Advanced High Strength Steels ◽  
Die Wear ◽  
Bending Under Tension

Advanced high strength steels (AHSS) have been widely used in vehicle structural components due to their high strength nature with balanced formability. In a typical application, a zinc coating is often required and applied to AHSS for the purpose of corrosion protection. Due to the high strength nature of AHSS, higher forming forces and binder pressures are also required in stamping AHSS, which often results in coating galling and die wear. The degree of coating galling and die wear depends upon forming process variables such as contact pressure, forming speed, lubrication and die temperatures. In this study, the Bending Under Tension (BUT) tester was used to evaluate the effects of these process variables on coating galling and die wear. Dual phase (DP) 590 and 780 steels with galvanized (GI) and galvannealed (GA) coatings were investigated in the study. The results indicate that GI coatings tend to have better wear resistance than GA coatings. A better surface treated (Thermo-Reactive Diffusion Vanadium Carbide) die material was also identified to decrease coating galling and die wear in stamping AHSS.

Design of Modern Steels for Automotive Application

2010 ◽  
Vol 638-642 ◽  
pp. 3111-3116 ◽  
Author(s):  
Harald Hofmann ◽  
Thomas Heller ◽  
Sascha Sikora
Keyword(s):  
High Strength Steels ◽  
Superplastic Forming ◽  
High Strength ◽  
Hot Forming ◽  
Automotive Application ◽  
Advanced High Strength Steels ◽  
Automobile Components ◽  
Multi Phase ◽  
Further Development ◽  
Complex Parts

Advanced high-strength steels offer a great potential for the further development of automobile bodies-in-white due to their combined mechanical properties of high formability and strength. New types of grades – multi-phase steels, superductile steels and density reduced steels – are under development at ThyssenKrupp Steel with tensile strength levels of up to 1000 MPa in combination with excellent formability for the high demands of cold formed structural automobile components. New forming technologies at increased temperatures – hot forming, semi-hot forming and superplastic forming - enable the processing of complex parts with extreme high strength. ThyssenKrupp Steel identifies potential future steels and technology concepts by technology monitoring and evaluates their potential for future applications in pre-development projects. University research institutions are significantly involved in this essential future oriented challenge. Seminal concepts are being implemented together with automotive manufactures by simultaneous engineering processes with coordinated phases of production and testing.

Forming Limit Curves and Forming Limit Stress Curves for Advanced High Strength Steels

2013 ◽  
Vol 773-774 ◽  
pp. 109-114 ◽  
Author(s):  
Sansot Panich ◽  
Frédéric Barlat ◽  
Vitoon Uthaisangsuk ◽  
Surasak Suranuntchai ◽  
Suwat Jirathearanat
Keyword(s):  
Yield Criterion ◽  
Flow Behavior ◽  
Constitutive Models ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Advanced High Strength Steels ◽  
Hardening Law ◽  
Limit Stress ◽  
Forming Limit Curves

Experimental and numerical investigations using Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) were carried out for two Advanced High Strength Steel (AHSS) grades DP780 and TRIP780. The forming limit curves were experimentally determined by means of Nakazima stretching test. Then, both FLC and FLSC were analytically calculated on the basis of the Marciniack-Kuczinsky (M-K) model. The yield criteria Barlat2000 (Yld2000-2d) were employed in combination with the Swift and modified Voce strain hardening laws to describe plastic flow behavior of the AHS steels. Hereby, influence of the constitutive models on the numerically determined FLCs and FLSCs were examined. Obviously, the forming limit curves predicted by the M-K model applying the Yld2000-2d yield criterion and Swift hardening law could fairly represent the experimental limit curves. The FLSCs resulted from the experimental data and theoretical model were also compared.

An Innovative Shearing Process for AHSS Edge Stretchability Improvements

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Hua-Chu Shih ◽  
Ming F. Shi
Keyword(s):  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Straight Edge ◽  
Forming Process ◽  
Expansion Test ◽  
Advanced High Strength Steels ◽  
Sheared Edge ◽  
Shear Edge

A beveled shear hole piercing process has recently been developed for advanced high strength steel (AHSS). The preliminary results have shown the new process is able to improve the quality of the sheared edge and the edge stretchability of AHSS. The goal of the current study is to optimize the beveled shearing process and identify the optimal shearing conditions for AHSS. Four different advanced high strength steels, including DP600, DP780, TRIP780, and DP980 with various thicknesses together with a conventional high strength steel, HSLA50, are selected in this study. The hole expansion test is used to evaluate the effect of shear edge conditions on the edge stretchability. The results show that an optimal selection of the die clearance and the shearing angle results in a less damaged edge, which significantly delays edge fracture in the forming process and increases the edge stretchability for AHSS. To further validate the advantages of the beveled shearing process in improving the shear edge quality of AHSS, a straight edge shearing device with the capability of adjusting the shearing variables (rake angles and die clearance) with respect to different sheet thicknesses was also developed and built. The edge stretchability of the straight edge sheared specimen was then evaluated using the sheared edge tension test. A similar trend to the beveled shear hole piercing process of AHSS is observed, and a significant improvement in the edge stretchability is also obtained with optimal shearing conditions.

Springback Investigation in Roll Forming of a V-Section

2014 ◽  
Vol 553 ◽  
pp. 643-648 ◽  
Author(s):  
Akbar Abvabi ◽  
Joseba Mendiguren ◽  
Bernard F. Rolfe ◽  
Matthias Weiss
Keyword(s):  
Elastic Modulus ◽  
Continuous Process ◽  
High Strength Steels ◽  
Shell Element ◽  
High Strength ◽  
Material Model ◽  
The Body ◽  
Roll Forming ◽  
Forming Process ◽  
Advanced High Strength Steels

To have fuel efficient vehicles with a lightweight structure, the use of High Strength Steels (HSS) and Advanced High Strength Steels (AHSS) in the body of automobiles is increasing. Roll forming is used widely to form AHSS materials. Roll forming is a continuous process in which a flat strip is shaped to the desired profile by passing through numerous sets of rolls. Formability and springback are two major concerns in the roll forming of AHSS materials. Previous studies have shown that the elastic modulus (Young’s modulus) of AHSS materials can change when the material undergoes plastic deformation and the main goal of this study is to numerically investigate the effect of a change in elastic modulus during forming on springback in roll forming. Experimental loading-unloading tests have been performed to obtain the material properties of TRIP 700 steel and incorporate those in the material model used in the numerical simulation of the roll forming process. The finite element simulations were carried out using MSC-Marc and two different element types, a shell element and a solid-shell element, were investigated. The results show that the elastic modulus diminution due to plastic strain increases the springback angle by about 60% in the simple V-section roll forming analyzed in this study.

Evaluation of Zinc Coating Adhesion in Stamping Advanced High Strength Steel

2014 ◽  
Author(s):  
Hua-Chu Shih
Keyword(s):  
Zinc Coating ◽  
High Strength Steels ◽  
High Strength ◽  
Strength Properties ◽  
Forming Process ◽  
Coating Adhesion ◽  
Advanced High Strength Steels ◽  
Adhesion Behavior ◽  
Lubrication Condition ◽  
Bending Under Tension

Advanced high strength steels (AHSS) have been widely used in vehicle structural components due to their high strength properties balanced with good formability. In many applications, a zinc coating is often applied to AHSS for the corrosion protection. Due to the high strength properties of AHSS, higher forming forces and binder pressures are also required in stamping AHSS, which often results in coating powdering/flaking or galling around the draw bead and die radius areas. The degree of coating powdering/flaking depends upon forming process variables such as draw bead force, forming speed, lubrication, and die temperatures. This study was designed to develop a lab-based coating adhesion test to quickly characterize the coating adhesion behavior of AHSS. In this study, both the bending under tension test and the modified draw bead test were used. A typical substrate of AHSS is coated with either a hot-dip Galvannealed (GA) or a Galvanized (GI) coating. In this study, dual phase (DP) steels with tensile strength levels of 600, 780 and 980 MPa were investigated at two different thicknesses and with two different coating types, GI and GA. The results reveal that GA tends to have worse coating adhesion than GI coatings under normal forming conditions. However, GI coatings are more sensitive to the lubrication condition and have worse coating adhesion than GA coatings under a larger draw bead penetration and smaller draw bead corner radius condition.

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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