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

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.

Rate-change instrumented indentation for measuring strain rate sensitivity

2009 ◽  
Vol 24 (4) ◽  
pp. 1466-1470 ◽  
Author(s):  
D. Pan ◽  
M.W. Chen
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Metallic Glasses ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
High Strength ◽  
Rate Change ◽  
Instrumented Indentation ◽  
Rate Dependent ◽  
Self Consistency

A rate-change instrumented indentation method is introduced to experimentally characterize the strain rate sensitivity of high strength materials, such as metallic glasses and nanocrystalline metals, which generally possess low rate sensitivity at room temperature. This technique has been validated herein, via self-consistency between rate jump and rate drop measurements, as a viable way to characterize rate dependent deformation behavior and thereby the underlying micromechanisms of plastic flow.

Dynamic Behaviour of High Strength Pipeline Steel

2012 ◽  
Author(s):  
F. Van den Abeele ◽  
J. Peirs ◽  
P. Verleysen ◽  
F. Oikonomides ◽  
J. Van Wittenberghe
Keyword(s):  
High Pressure ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Void Growth ◽  
High Strain ◽  
Pipeline Steel ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strain Rates ◽  
Constitutive Behaviour

The occurrence of a longitudinal crack propagating along a gas pipeline is a catastrophic event, which involves both economic losses and environmental damage. Hence, the fracture propagation control is essential to ensure pipeline integrity. The commonly used ductile fracture control strategy for the design of high pressure pipelines is the Battelle Two Curve Method. This approach stipulates that if there is a crack speed at a given pressure that exceeds the gas decompression velocity at the same pressure, propagation will occur. However, for high strength pipeline steels, this method does not yield conservative predictions, as the absorbed impact energy during a Charpy test no longer reflects the actual burst behaviour of the pipe. Enhanced toughness measures, like Crack Tip Opening Angle and instrumented Battelle Drop Weight Tear test are being proposed as alternative options. These emerging toughness tests are complemented by numerical simulations of ductile crack propagation and arrest. Most of these models are based on the computation of void growth, and account for the local softening of the material due to void growth and subsequent coalescence. The constitutive behaviour of the sound pipeline steel is often modelled as merely an elastoplastic law, measured under quasi-static conditions. However, both Charpy tests and Battelle tests are dynamic events, which require knowledge of the strain rate sensitivity of the pipeline material. In addition, very high strain rates can occur in the vicinity of a running crack in a high pressure gas pipeline. Hence, the constitutive model for the pipeline steel has to account for strain rate sensitivity. In this paper, Split Hopkinson Tensile Bar (SHTB) experiments are reported on high strength pipeline steel. Notched tensile tests are performed at high strain rates, to assess the influence of both strain rate sensitivity and triaxiality on the response of the material. In addition, dynamic experiments are conducted at low temperatures (−70°C) to evaluate the ductility of pipeline steel under such severe conditions. The results allow discriminating between the effects of strain rate, triaxiality and temperature, and provide reliable experimental data to accurately model the constitutive behaviour of high strength pipeline steel.

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.

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