The mechanical properties of pure iron tested in compression over the temperature range 2 to 293 °K

1967 ◽  
Vol 261 (1121) ◽  
pp. 253-287 ◽  
Keyword(s):  
Mechanical Properties ◽  
Flow Stress ◽  
Strain Rate ◽  
Single Crystals ◽  
Yield Stress ◽  
Low Temperatures ◽  
Pure Iron ◽  
Constant Strain Rate ◽  
Frictional Stress ◽  
Strain And Strain Rate

The mechanical properties of pure iron single crystals and of polycrystalline specimens of a zone-refined iron have been measured in compression over the temperature and strain rate ranges 2.2 to 293 °K and 7 x 10 -7 to 7 x 10 -3 s -1 respectively. Various yield stress parameters were determined as functions of both temperature and strain rate, and the reversible changes in flow stress produced by isothermal changes of strain rate or by changes of temperature at constant strain rate were also measured as functions of temperature, strain and strain rate. Both the temperature variation of the flow stress and the strain rate sensitivity of the flow stress were generally identical for the single crystals ( ca. 0.005/M carbon) and the polycrystalline specimens ( ca. 9/M carbon). At low temperatures, the temperature dependence of the yield stress was smaller than that of the flow stress at high strains, probably because of the effects of mechanical twinning, but once again the behaviour of single and polycrystalline specimens was very similar. Below 10 °K, both the flow stress and the extrapolated yield stress were independent of temperature. The results show that macroscopic yielding and flow at low temperatures are both governed by the same deformation mechanism, which is not very impurity sensitive, even in the very low carbon range covered by the experiments. The flow stress near 0 °K is ca. 5.8 x 10 -3 u where [i is the shear modulus. On the basis of a model for thermally activated flow, the activation volume at low temperatures (high stresses) is found to be ca. 5 b 3 . The exponent in the empirical power law for the dislocation velocity against stress relation is ca. 3 near room temperature, but becomes quite large at low temperatures. The results indicate that macroscopic deformation at low temperatures is governed by some kind of lattice frictional stress (Peierls-Nabarro force) acting on dislocations.

scholarly journals The Mechanical Properties of Single Crystals of Pure Ice

1969 ◽  
Vol 8 (54) ◽  
pp. 463-473 ◽  
Author(s):  
S. J. Jones ◽  
J. W. Glen
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Single Crystals ◽  
Fracture Stress ◽  
Constant Strain Rate ◽  
Tensile Creep ◽  
Stress Dependence ◽  
Creep Tests ◽  
Dislocation Multiplication ◽  
Compressive Tests

AbstractResults obtained from tensile and compressive tests on pure ice single crystals at various temperatures down to −90°C are reported. At −50°C tensile creep tests give a continually increasing creep rate until fracture, as observed at higher temperatures. The stress dependence of the strain-rate is discussed. Fracture stress increases with decreasing temperature. Results from constant strain-rate compressive tests are compared with theoretical curves computed from Johnston’s (1962) theory of dislocation multiplication. A dislocation velocity of the order of 0.5×10−8 m s−1 is deduced for ice at −50°C.

Strain Rate Dependence of the Flow Stress and Work-Hardening of Single Crystals of NI3(Al,Hf)B

1994 ◽  
Vol 364 ◽  
Author(s):  
S. S. Ezz ◽  
Y. Q. Sun ◽  
P. B. Hirsch
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Yield Stress ◽  
Strain Rate Sensitivity ◽  
Work Hardening ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Controlling Mechanism

AbstractThe strain rate sensitivity ß of the flow stress τ is associated with workhardening and β=(δτ/δln ε) is proportional to the workhardening increment τh = τ - τy, where τy is the strain rate independent yield stress. The temperature dependence of β/τh reflects changes in the rate controlling mechanism. At intermediate and high temperatures, the hardening correlates with the density of [101] dislocations on (010). The nature of the local obstacles at room temperature is not established.

scholarly journals The Mechanical Properties of Single Crystals of Pure Ice

1969 ◽  
Vol 8 (54) ◽  
pp. 463-473 ◽  
Author(s):  
S. J. Jones ◽  
J. W. Glen
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Single Crystals ◽  
Fracture Stress ◽  
Constant Strain Rate ◽  
Tensile Creep ◽  
Stress Dependence ◽  
Creep Tests ◽  
Dislocation Multiplication ◽  
Compressive Tests

Abstract Results obtained from tensile and compressive tests on pure ice single crystals at various temperatures down to −90°C are reported. At −50°C tensile creep tests give a continually increasing creep rate until fracture, as observed at higher temperatures. The stress dependence of the strain-rate is discussed. Fracture stress increases with decreasing temperature. Results from constant strain-rate compressive tests are compared with theoretical curves computed from Johnston’s (1962) theory of dislocation multiplication. A dislocation velocity of the order of 0.5×10−8 m s−1 is deduced for ice at −50°C.

Stress response by the strain-rate change in binary, stoichiometric Ni3AI single crystal

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Demura ◽  
T. Hirano
Keyword(s):  
Steady State ◽  
Stress Response ◽  
Flow Stress ◽  
Strain Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Yield Stress ◽  
Temperature Region ◽  
Steady State Flow ◽  
Strain Rate Change

ABSTRACTThe strain-rate dependence of flow stress in single crystals of binary, stoichiometric Ni3Al was studied in the temperature region of the yield stress anomaly. Below 400 K, the steady-state flow stress was found to be independent of strain rate, though it changed temporarily when the strain rate was changed. The strain-rate insensitivity can be explained by assuming that the flow stress is controlled by the multiplication/immobilization of mobile dislocations.

The Temperature Dependence of the Mechanical Properties of Gamma TiAl

1994 ◽  
Vol 364 ◽  
Author(s):  
B. Viguier ◽  
J. Bonneville ◽  
K. J. Hemker ◽  
J. L. Martin
Keyword(s):  
Mechanical Properties ◽  
Flow Stress ◽  
Strain Rate ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Dislocation Motion ◽  
Compression Tests ◽  
Wide Range

AbstractMechanical properties of a polycrystalline single phased γ Ti47Al51Mn2 alloy were studied by compression tests in a wide range of temperature (100 K - 1300 K). We report, in this paper, the temperature dependence of both the flow stress and its strain rate sensitivity. These dependencies show the existence of three temperature domains corresponding to different dislocation motion mechanisms. The temperature dependence of the flow stress strain rate sensitivity is compared with values measured in single crystals1.

A Modified Peric Model for Al-Mg Alloy Sheet with Rate-Independent Initial Yield Stress at Warm Temperatures

2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Models ◽  
Mg Alloy ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Dependent Flow

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.

Effects of ternary additions on the deformation behavior of single crystals of MoSi2

2000 ◽  
Vol 646 ◽  
Author(s):  
Haruyuki Inui ◽  
Koji Ishikawa ◽  
Masaharu Yamaguchi
Keyword(s):  
Yield Strength ◽  
Strain Rate ◽  
Single Crystals ◽  
Creep Strain ◽  
High Temperatures ◽  
Low Temperatures ◽  
Deformation Behavior ◽  
Creep Strain Rate ◽  
Compression Creep ◽  
Ternary Additions

ABSTRACTEffects of ternary additions on the deformation behavior of single crystals of MoSi2 with the hard [001] and soft [0 15 1] orientations have been investigated in compression and compression creep. The alloying elements studied include V, Cr, Nb and Al that form a C40 disilicide with Si and W and Re that form a C11b disilicide with Si. The addition of Al is found to decrease the yield strength of MoSi2 at all temperatures while the additions of V, Cr and Nb are found to decrease the yield strength at low temperatures and to increase the yield strength at high temperatures. In contrast, the additions of W and Re are found to increase the yield strength at all temperatures. The creep strain rate for the [001] orientation is significantly lower than that for the [0 15 1] orientation. The creep strain rate for both orientations is significantly improved by alloying with ternary elements such as Re and Nb.

An Assessment of the Method Used to Determine Activation Parameters in L12 Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
B. Matterstock ◽  
G. Saada ◽  
J. Bonneville ◽  
J. L Martin
Keyword(s):  
Mechanical Properties ◽  
Theoretical Analysis ◽  
Plastic Strain ◽  
Strain Rate ◽  
Characteristic Time ◽  
Constant Strain Rate ◽  
Activation Parameters ◽  
Plastic Strain Rate ◽  
Clear Indication ◽  
Load Relaxation

ABSTRACTThe characterisation of dislocation mechanisms in connection with macroscopic mechanical properties are usually performed through transient tests, such as strain-rate jumps, load relaxations or creep experiments. The present paper includes a careful and complete theoretical analysis of the relaxation and the creep kinetics. We experimentally show that the plastic strain-rate is continuous at the transition between constant strain-rate conditions and both load relaxation and creep test. The product of the plastic strain-rate at the onset of the transient test () with the characteristic time (tk) of the transient is found to be independent of , as theoretically expected. This is a clear indication that the assumptions underlying the theoretical analysis are relevant.

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