scholarly journals Advanced Crystal Plasticity Modeling of Multi-Phase Steels: Work-Hardening, Strain Rate Sensitivity and Formability

2021 ◽  
Vol 11 (13) ◽  
pp. 6122
Author(s):  
Jesús Galán-López ◽  
Behnam Shakerifard ◽  
Jhon Ochoa-Avendaño ◽  
Leo A. I. Kestens
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Crystal Plasticity ◽  
High Strength Steels ◽  
Grain Morphology ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Forming Limit ◽  
Biaxial Tests

This work presents an advanced crystal plasticity model for the simulation of the mechanical behavior of multiphase advanced high-strength steels. The model is based on the Visco-Plastic Self-Consistent (VPSC) model and uses information about the material’s crystallographic texture and grain morphology together with a grain constitutive law. The law used here, based on the work of Pantleon, considers how dislocations are created and annihilated, as well as how they interact with obstacles such as grain boundaries and inclusions (carbides). Additionally, strain rate sensitivity is implemented using a phenomenological expression derived from literature data that does not require any fitting parameter. The model is applied to the study of two bainitic steels obtained by applying different heat treatments. After fitting the required parameters using tensile experiments in different directions at quasi-static and high strain rates, formability properties are determined using the model for the performance of virtual experiments: uniaxial tests are used to determine r-values and stress levels and biaxial tests are used for the calculation of yield surfaces and forming limit curves.

The Effect of Strain Rate on Yielding in High Strength Steels

1966 ◽  
Vol 88 (1) ◽  
pp. 37-44 ◽  
Author(s):  
D. P. Kendall ◽  
T. E. Davidson
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Power Law ◽  
High Strength Steels ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strain Rates ◽  
Alloy Steels ◽  
Strength Alloy ◽  
Continuous Power

The effect of strain rates ranging from 10−4 to 10 in/in/sec on the yield strengths of several high strength alloy steels is investigated. Quenched and tempered-type alloys exhibit two regions of strain-rate sensitivity with the strain rate dividing the sensitive and insensitive regions varying from 0.5 to greater than 10 in/in/sec, depending on composition, microstructure and grain size. At the higher rates a power-law relationship is found which is consistent with a yielding model involving breakaway of dislocations from solute atmospheres. Maraging steel exhibits a continuous power law-strain rate sensitivity over the entire range.

Advanced High Strength Steels for Automobile Body Structures

2007 ◽  
Vol 539-543 ◽  
pp. 4386-4390 ◽  
Author(s):  
M. Takahashi ◽  
A. Uenishi ◽  
H. Yoshida ◽  
H. Kuriyama
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
High Strength Steels ◽  
Rate Sensitivity ◽  
High Strength ◽  
Thin Wall ◽  
Advanced High Strength Steels ◽  
Limited Length ◽  
Side Collision ◽  
Frontal Collisions

There has been a big demand for increased vehicle safety and weight reduction of auto-bodies. An extensive use of high strength steels is one of the ways to answer the requirement. Since the crashworthiness is improved by applications of higher strength steels to crashworthiness conscious structural components, various types of advanced high strength steels have been developed. The crash energy during frontal collisions is absorbed by the buckling and bending deformations of thin wall tube structures of the crushable zone of auto-bodies. In the case of side collision, on the other hand, a limited length of crushable zone requires the components to minimize the deformation during the collision. The lower the strength during press forming, the better the press formability is expected. However, the higher the strength at a collision event, the better the crashworthiness can be obtained. It can, therefore, be concluded that steels with higher strain rate sensitivities are desired. Combinations of soft ferrite phase and other hard phases were found to improve the strain rate sensitivity of flow stresses. Bake hardening is also one of the ways to improve the strain rate sensitivity of flow stresses.

Strain-Rate Effect on the Tensile Behaviour of High Strength Alloys

2011 ◽  
Vol 82 ◽  
pp. 124-129 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Stefano Bianchi
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Cross Sectional ◽  
Split Hopkinson Tensile Bar ◽  
Wide Range ◽  
First Results

In this paper the first results of the mechanical characterization in tension of two high strength alloys in a wide range of strain rates are presented. Different experimental techniques were used for different strain rates: a universal machine, a Hydro-Pneumatic Machine and a JRC-Split Hopkinson Tensile Bar. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. An increase of the stress at a given strain increasing the strain-rate from 10-3 to 103 s-1, a moderate strain-rate sensitivity of the uniform and fracture strain, a poor reduction of the cross-sectional area at fracture with increasing the strain-rate were shown. Based on these experimental results the parameters required by the Johnson-Cook constitutive law were determined.

scholarly journals Deformation Texture Evolution in Flat Profile AlMgSi Extrusions: Experiments, FEM, and Crystal Plasticity Modeling

2021 ◽  
Vol 8 ◽  
Author(s):  
Tomas Manik ◽  
Knut Marthinsen ◽  
Kai Zhang ◽  
Arash Imani Aria ◽  
Bjørn Holmedal
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Crystal Plasticity ◽  
Texture Evolution ◽  
Rate Sensitivity ◽  
Deformation Texture ◽  
Fiber Texture ◽  
Electron Back Scatter Diffraction ◽  
Slip Systems ◽  
Flat Profile

In the present work, the deformation textures during flat profile extrusion from round billets of an AA6063 and an AA6082 aluminium alloy have been numerically modeled by coupling FEM flow simulations and crystal plasticity simulations and compared to experimentally measured textures obtained by electron back-scatter diffraction (EBSD). The AA6063 alloy was extruded at a relatively low temperature (350°C), while the AA6082 alloy, containing dispersoids that prevent recrystallization, was extruded at a higher temperature (500°C). Both alloys were water quenched at the exit of the die, to maintain the deformation texture after extrusion. In the center of the profiles, both alloys exhibit a conventional β-fiber texture and the Cube component, which was significantly stronger at the highest extrusion temperature. The classical full-constraint (FC)-Taylor and the Alamel grain cluster model were employed for the texture predictions. Both models were implemented using the regularized single crystal yield surface. This approach enables activation of any number and type of slip systems, as well as accounting for strain rate sensitivity, which are important at 350°C and 500°C. The strength of the nonoctahedral slips and the strain-rate sensitivity were varied by a global optimization algorithm. At 350°C, a good fit could be obtained both with the FC Taylor and the Alamel model, although the Alamel model clearly performs the best. However, even with rate sensitivity and nonoctahedral slip systems invoked, none of the models are capable of predicting the strong Cube component observed experimentally at 500°C.

scholarly journals The strain-rate sensitivity of high-strength high-toughness steels.

2006 ◽  
Author(s):  
M F Dilmore ◽  
Thomas B Crenshaw ◽  
Brad Lee Boyce
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
High Strength ◽  
High Toughness
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