scholarly journals Inelastic Constitutive Equation on the Basis of Distribution Function of Yield Stress : (Basic Equation and Parameter for Work Hardening and Softening)

1989 ◽  
Vol 32 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Yasushi NIITSU ◽  
Kozo IKEGAMI
Keyword(s):  
Distribution Function ◽  
Constitutive Equation ◽  
Yield Stress ◽  
Work Hardening ◽  
Basic Equation ◽  
Hardening And Softening

Identification of the constitutive equation by the indentation technique using plural indenters with different apex angles

2001 ◽  
Vol 16 (8) ◽  
pp. 2283-2292 ◽  
Author(s):  
Masatoshi Futakawa ◽  
Takashi Wakui ◽  
Yuji Tanabe ◽  
Ikuo Ioka
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Work Hardening ◽  
Indentation Technique ◽  
Work Hardening Coefficient ◽  
The Relationship ◽  
Stress Work ◽  
Hardening Coefficient ◽  
Depth Curve ◽  
Work Hardening Exponent

This paper describes a novel technique for determining the constitutive equation of elastic–plastic materials by the indentation technique using plural indenters with different apex angles. Finite element method (FEM) analyses were carried out to evaluate the effects of yield stress, work hardening coefficient, work hardening exponent, and the apex angle of indenter on the load–depth curve obtained from the indentation test. As a result, the characterized curves describing the relationship among the yield stress, work hardening coefficient, and the work hardening exponent were established. Identification of the constants of a constitutive equation was made on the basis of the relationship between the characterized curves and the hardness given by the load–depth curve. This technique was validated through experiments on Inconel 600 and aluminum alloy. The determined constitutive equation was applied to the FEM analyses to simulate the deformation including necking behavior under uniaxial tension. The analytical results are in good agreement with experimental results.

Anomaly of the Work Hardening of Zn-Cu Single Crystals Oriented for Slip in Secondary Systems

2011 ◽  
Vol 56 (4) ◽  
pp. 1021-1027
Author(s):  
K. Pieła
Keyword(s):  
Strain Hardening ◽  
Single Crystals ◽  
Yield Stress ◽  
Work Hardening ◽  
Temperature Anomaly ◽  
Strain Hardening Exponent ◽  
Plastic Behavior ◽  
Thermal Dependence ◽  
Copper Addition ◽  
Secondary Systems

Anomaly of the Work Hardening of Zn-Cu Single Crystals Oriented for Slip in Secondary SystemsThe copper alloyed (up to 1.5%) zinc single crystals oriented for slip in non-basal systems (orientation close to < 1120 >) were subjected to compression test within a range of temperatures of 77-293K. It has been stated, that Zn-Cu crystals exhibit characteristic anomalies of the thermal dependence of yield stress and of the strain hardening exponent. Both of them are related to the change in type and sequence of active non-basal slip systems: pyramidal of the 1storder {1011} < 1123 > (Py-1) and pyramidal of the 2ndorder {1122} < 1123 > (Py-2). The temperature anomaly of the yield stress results from the change of the slip from Py-2 systems to simultaneous slip in the Py-2 and Py-1 (Py-2 + Py-1) systems, occurring in the preyielding stage. On the other hand, sequential activation of pyramidal systems taking place in advanced plastic stage (i.e. the first Py-2 and next Py-2 + Py-1 systems) is responsible for temperature anomaly of strain hardening exponent. Increase in copper addition favors the activity of Py-2 systems at the expense of Py-1 slip, what leads to a drastic differences in plastic behavior of zinc single crystals.

The Effects of Interstitial Content and Annealing on the Flow and Fracture behavior of Polycrystalline ÿ-NiAl

1994 ◽  
Vol 364 ◽  
Author(s):  
M. L. Weaver ◽  
V. Levit ◽  
M. J. Kaufman ◽  
R. D. Noebe
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Work Hardening ◽  
Strain Aging ◽  
Fracture Behavior ◽  
Rate Sensitivity ◽  
Dynamic Strain ◽  
Aging Behavior ◽  
Aging Theories ◽  
Tenfold Increase

AbstractThe strain aging behavior of three polycrystalline NiAl alloys has been investigated at temperatures between 300 and 1200 K. Yield stress plateaus, yield stress transients upon a tenfold increase in strain rate, work hardening peaks, and dips in the strain rate sensitivity (SRS) have been observed between 700 and 800 K. These observations are indicative of dynamic strain aging (DSA) and are discussed in terms of conventional strain aging theories.

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.

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