Concentration dependence of the influence of strain rate on the yield stress of doped NaCl crystals under uniaxial compression in the temperature range 77–773 K

1998 ◽  
Vol 24 (2) ◽  
pp. 94-96
Author(s):  
R. P. Zhitaru ◽  
N. A. Palistrant ◽  
V. A. Rakhvalov

2008 ◽  
Vol 1128 ◽  
Author(s):  
Markus W. Wittmann ◽  
Janelle M. Chang ◽  
Yifeng Liao ◽  
Ian Baker

AbstractThe effects of strain rate and temperature on the yield strength of near-stoichiometric Fe2AlMn single crystals were investigated. In the temperature range 600-800K the yield stress increased with increasing temperature, a response commonly referred to as a yield strength anomaly. No strain rate sensitivity was observed below 750K, but at higher temperatures the yield stress increased with increasing strain rate. Possible mechanisms to explaining the effects of temperature and strain rate are discussed.



2019 ◽  
Author(s):  
Minai Zhang ◽  
Xin Wang ◽  
Alexander D. Dupuy ◽  
Julie M. Schoenung ◽  
Xiaoqiang Li


Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  


2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin

The constitutive modeling of aluminum alloy under warm forming conditions generally considers the influence of temperature and strain rate. It has been shown by published flow stress curves of Al-Mg alloy that there is nearly no effect of strain rate on initial yield stress at various temperatures. However, most constitutive models ignored this phenomenon and may lead to inaccurate description. In order to capture the rate-independent initial yield stress, Peric model is modified via introducing plastic strain to multiply the strain rate, for eliminating the effect of strain rate when the plastic strain is zero. Other constitutive models including the Wagoner, modified Hockett–Sherby and Peric are also considered and compared. The results show that the modified Peric model could not only describe the temperature-and rate-dependent flow stress, but also capture the rate-independent initial yield stress, while the Wagoner, modified Hockett–Sherby and Peric model can only describe the temperature-and rate-dependent flow stress. Moreover, the modified Peric model could obtain proper static yield stress more naturally, and this property may have potential applications in rate-dependent simulations.



1998 ◽  
Vol 39 (9) ◽  
pp. 1289-1294 ◽  
Author(s):  
Kee Ahn Lee ◽  
Chong Soo Lee


2004 ◽  
Vol 449-452 ◽  
pp. 577-580
Author(s):  
Young Sang Na ◽  
Young Mok Rhyim ◽  
J.Y. Lee ◽  
Jae Ho Lee

In order to quantitatively analyze the critical strain for the initiation of dynamic recrystallization in Ni-Fe-based Alloy 718, a series of uniaxial compression tests was conducted in the temperature range 927°C - 1066°C and the strain rate range 5 x 10-4s-1- 5 s-1with varying initial grain size. The critical strains were graphically determined based on one parameter approach and microscopically confirmed. The effect of γ'' (matrix-hardening phase) and δ (grain boundary phase)on the critical strain was simply discussed. The constitutive model for the critical strain of Alloy 718 was constructed using the experimental data obtained from the higher strain rate and the temperature range between 940°C and 1040°C.



1981 ◽  
Vol 86 (B10) ◽  
pp. 9299-9311 ◽  
Author(s):  
Osam Sano ◽  
Ichiro Ito ◽  
Makoto Terada


1965 ◽  
Vol 180 (1) ◽  
pp. 285-294 ◽  
Author(s):  
F. U. Mahtab ◽  
W. Johnson ◽  
R. A. C. Slater

The dynamic indentation of copper (B.S. 1433) and an aluminium alloy (B.S. 1476 HE 10) has been investigated, using cylindro-conical projectiles fired from an air-actuated gun. The experiments were performed with impact velocities varying between 1000 and 2500 in/s and at elevated temperatures up to 600°C for the copper and 550°C for the aluminium alloy. The magnitude of the corresponding range of mean strain rate was then 103-104/s, depending upon the material; impact velocity and temperature (see Appendix I). For the range of impact velocities investigated no consequential transition temperature † was encountered. The dynamic temperature coefficient† thus remained constant throughout the test temperature range for each material. This dynamic temperature coefficient was found to be equal to the static temperature coefficient corresponding to the sub-transitional temperature range for the respective materials. The mean effective dynamic indentation pressure is shown to decrease with temperature but the ratio of this dynamic pressure to the static indentation pressure increases with temperature. Strain rate effects for both materials were negligible for sub-transitional temperatures but become important at super-transitional temperatures. It was observed that the parameters on which the strain rate effect depends are in some way related to the absolute melting point of a pure metal.



Author(s):  
Munir Al-Saadi ◽  
Christopher Hulme-Smith ◽  
Fredrik Sandberg ◽  
Pär G. Jönsson

AbstractAlloy 825 is a nickel-based alloy that is commonly used in applications where both high strength and corrosion resistance are required, such as tanks in the chemical, food and petrochemical industries and oil and gas pipelines. Components made from Alloy 825 are often manufactured using hot deformation. However, there is no systematic study to optimise the processing conditions reported in literature. In this study, a processing map for as-cast Alloy 825 is established to maximise the power dissipation efficiency of hot deformation in the temperature range of 950 to 1250 °C at an interval of 50 °C and strain rate range of $$0.01\, {\text{s}}^{ - 1}$$ 0.01 s - 1 to $$10.0\, {\text{s}}^{ - 1}$$ 10.0 s - 1 to a true strain of $$0.7$$ 0.7 using a Gleeble-3500 thermomechanical simulator. The processing conditions are also correlated to the Vickers hardness of the final material, which is also characterised using optical microscopy and scanning electron microscopy, including electron backscattered diffraction. The true stress-true strain curves exhibit peak stresses followed by softening due to occurrence of dynamic recrystallization. The activation energy for plastic flow in the temperature range tested is approximately $$450\,{\text{ kJ mol}}^{ - 1}$$ 450 kJ mol - 1 , and the value of the stress exponent in the (hyperbolic sine-based) constitutive equation, $$n = 5.0$$ n = 5.0 , suggests that the rate-limiting mechanism of deformation is dislocation climb. Increasing deformation temperature led to a lower Vickers hardness in the deformed material, due to increased dynamic recrystallization. Raising the strain rate led to an increase in Vickers hardness in the deformed material due to increased work hardening. The maximum power dissipation efficiency is over $$35\%$$ 35 % , obtained for deformation in the temperature range 1100-1250 °C and a strain rate of $$0.01\, {\text{s}}^{ - 1}$$ 0.01 s - 1 -$$0.1\, {\text{s}}^{ - 1}$$ 0.1 s - 1 . These are the optimum conditions for hot working.



Sign in / Sign up

Export Citation Format

Share Document