Resistance to dynamic compression of low-carbon steel and alloy steels at elevated temperatures and at high strain-rates

Brittle-ductile transition (BDT) behaviour was investigated in low carbon steel deformed by an accumulative roll-bonding (ARB) process. The temperature dependence of its fracture toughness was measured by conducting four-point bending tests at various temperatures and strain rates. The fracture toughness increased while the BDT temperature decreased in the specimens deformed by the ARB process. Arrhenius plots between the BDT temperatures and the strain rates indicated that the activation energy for the controlling process of the BDT was not changed by the deformation with the ARB process. It was deduced that the decrease in the BDT temperature by grain refining was not due to the increase in the dislocation mobility controlled by short-range barriers. Quasi-three-dimensional simulations of dislocation dynamics, taking into account of crack tip shielding due to dislocations, were performed to investigate the effect of a dislocation source spacing along a crack front on the BDT. The simulation indicated that the BDT temperature is decreased with decreasing in the dislocation source spacing. Molecular dynamics simulations revealed that moving dislocations were impinged against grain boundaries and were reemitted from there with increasing strain. It indicates that grain boundaries can be new sources in ultra-fine grained materials, which increases toughness at low temperatures.

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The relationship between brittle fracture and the high strain fatigue behaviour of a low carbon steel

International Journal of Mechanical Sciences ◽

10.1016/0020-7403(71)90082-8 ◽

1971 ◽

Vol 13 (11) ◽

pp. 959-970

Author(s):

K.C. Rockey ◽

D.W. Griffiths ◽

C.C.B. Day

Keyword(s):

Carbon Steel ◽

Brittle Fracture ◽

High Strain ◽

Low Carbon Steel ◽

Fatigue Behaviour ◽

Low Carbon ◽

The Relationship

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Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

Volume 2: Processing ◽

10.1115/msec2014-4064 ◽

2014 ◽

Author(s):

V. S. Brooks ◽

Y. B. Guo

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

High Strain ◽

Split Hopkinson Pressure Bar ◽

Dynamic Compression ◽

Orthopedic Implants ◽

Strain Rates ◽

High Strain Rates ◽

Static Compression ◽

Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

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Comparison Study of Oxidation Behavior of Low Carbon Steel at Elevated Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1025-1026.504 ◽

2014 ◽

Vol 1025-1026 ◽

pp. 504-508 ◽

Cited By ~ 1

Author(s):

Sang An Ha ◽

Dong Kyun Kim ◽

Woo Jin Lee ◽

Chang Yong Kang ◽

Kwon Hoo Kim ◽

...

Keyword(s):

Carbon Steel ◽

Oxidation Rate ◽

Cyclic Oxidation ◽

Oxidation Behavior ◽

Elevated Temperatures ◽

Low Carbon Steel ◽

Comparison Study ◽

Low Carbon ◽

Increasing Temperature ◽

Continuous Oxidation

Comparison study of oxidation behavior of low carbon steel was conducted at the temperature range of 500°C to 700°C under a 0.2 atm oxygen pressure by continuous and discontinuous oxidation methods. Oxidation rate of both cases was found to be increased with increasing temperature from 500°C to 700°C and obeyed parabolic rate law. In addition, activation energy for the continuous oxidation of steel was found to be a 164.8 kJ/mole, which means that oxidation rate is proportionally dependant on temperature. In case of cyclic oxidation, the oxidation rate was shown to faster than continuous oxidation at all temperatures due to direction oxidation through spallation of the oxide layer.

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