A Constitutive Description of Aluminum-1% Magnesium Alloy Deformed Under Hot-Working Conditions

2001 ◽  
Vol 123 (3) ◽  
pp. 301-308 ◽  
Author(s):  
E. S. Puchi Cabrera
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Temperature Dependence ◽  
Working Conditions ◽  
Work Hardening ◽  
Hot Working ◽  
Initial Flow ◽  
Work Hardening Rate ◽  
Initial Work

A constitutive description of the deformation of commercial aluminum-1% magnesium alloy (AA5005) under hot working conditions has been formulated on a rational basis. The strain dependence of the flow stress is described by means of the evolution law earlier advanced by Sah et al. The optimization procedure of the experimental stress-strain data allowed the determination the extrapolated values of the initial flow stress and saturation stress which were subsequently correlated with temperature and strain rate by means of the kinetic model proposed by Kocks. It is shown that the initial work-hardening rate of this alloy is strongly dependent both on temperature and strain rate and that the temperature dependence is much more significant than that explained by the temperature dependence of the shear modulus of aluminum. The best description of the experimental flow stress data is obtained by expressing the initial work-hardening rate as a function of the effective strain rate, in terms of a simple parametric relationship, rather than considering a constant value for this parameter, independent of temperature and strain rate. The accuracy of the constitutive description proposed, regarding the reproduction of both the experimental flow stress and work-hardening rate, makes it reliable for its use in the analysis of hot-working processes involving this material.

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.

Flow Stress Equations for Type 304 Stainless and AISI 1055 Steels

1985 ◽  
Vol 107 (2) ◽  
pp. 97-100 ◽  
Author(s):  
P. Dadras
Keyword(s):  
Experimental Data ◽  
Stainless Steel ◽  
Flow Stress ◽  
Strain Rate ◽  
Working Conditions ◽  
Hot Working ◽  
304 Stainless Steel ◽  
Strain Behavior ◽  
Type 304 ◽  
Type 304 Stainless Steel

A model for stress-strain behavior under hot working conditions has been proposed. Based on experimental data, equations for the dependence of flow stress on strain, strain rate, and temperature have been developed. Application to type 304 stainless steel and AISI 1055 steel has been demonstrated.

scholarly journals Hot deformation behavior of 60NiTi shape-memory alloy fabricated by hot isostatic pressing

2022 ◽  
Author(s):  
Mei-ling Li ◽  
Wen-jin Gao ◽  
Ying-hao Zhou
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Work Hardening ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Dynamic Equilibrium ◽  
High Stress ◽  
Cylindrical Sample ◽  
Hot Working ◽  
Hot Deformation Behavior

Abstract The 60NiTi (Ni60wt%–Ti40wt%) intermetallic is a hard-to-process material. Understanding of hot deformation behavior is crucial for the hot working of 60NiTi. This work studied hot deformation behavior and corresponding microstructure of the hot isostatic pressed 60NiTi in the temperature range of 900 °C–1050 °C and at strain rates of 0.1, 0.01, and 0.001 s-1 through a hot compression test. The flow stress and microstructure were susceptible to the hot deformation parameters. The flow stress decreased with the increase in deformation temperature and decrease in strain rate. Work hardening occurred at a small strain, then followed by softening; finally, near-dynamic equilibrium was achieved between work hardening and softening. A constitutive equation was developed to describe the effects of strain rate and temperature on flow stress. Simulation of hot deformation via the finite element method revealed the workpiece’s inhomogeneous deformation. The deformation occurred mainly in the center area of the cylindrical sample, resulting in high stress and strain concentrations in this region and causing the equiaxial grains to be compressed into prolate grains. This work can provide guidance for the hot working, such as forging and hot rolling, of 60NiTi.

On the Mechanical Threshold Stress of Aluminum: Effect of the Alloying Content

2001 ◽  
Vol 123 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Eli S. Puchi-Cabrera ◽  
Crisanto Villalobos-Gutie´rrez ◽  
Gonzalo Castro-Farin˜as
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Working Conditions ◽  
Threshold Stress ◽  
Solute Concentration ◽  
Strain Rates ◽  
Solute Content ◽  
Mechanical Threshold ◽  
Work Hardening Rate ◽  
Aluminum Effect

The mechanical behavior of aluminum with different alloying contents up to 1 wt percent, deformed under hot-working conditions, has been analyzed in terms of the exponential saturation equation proposed by Voce for the description of the evolution of the mechanical threshold stress, σ^, and the model advanced by Kocks for the description of the ratio, sε˙,T, between the flow stress at any strain rate and temperature and σ^. It has been determined that the increase in the alloying content of aluminum gives rise to an increase in the mechanical threshold stress mainly due to the effect of the solute content on the saturation stress, σ^s and less markedly on the athermal stress, σ^a. On the contrary, it has been found that the increase in the alloying content gives rise to a decrease of the Stage II or athermal work-hardening rate, θ0. Also, it has been concluded that the increase in the solute content of the material gives rise to a significant increase in the parameters ε˙K and g0 that enter into the expression of sε˙,T. Therefore, the dependence of the flow stress at any temperature and strain rate with the alloying content evolves from the dependence of both sε˙,T and σ^ on solute concentration. Also, it has been found that, for the present analysis, the factor sε˙,T derived from Kocks model is more satisfactory than that derived from the Follansbee and Kocks model since the latter predicts negative values of the flow stress below approximately 10 MPa, that is to say, under conditions of elevated deformation temperatures and low strain rates.

scholarly journals The Temperature and Strain Rate Dependence of the Flow Stress of Single Crystal Nial Deformed Along

1994 ◽  
Vol 364 ◽  
Author(s):  
Stuart A Maloy ◽  
George T Gray
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Single Crystal ◽  
Work Hardening ◽  
Rate Dependence ◽  
Temperature Sensitive ◽  
Strain Rates ◽  
Slip Bands ◽  
Work Hardening Rate ◽  
Slip Traces

AbstractSingle crystal NiAl and Ni-49.75Al-0.25Fe have been deformed along <110> at temperatures of 77, 298 and 773K and strain rates of 0.001/s, 0.1/s and 2000/s. The flow stress of <110> NiAl is rate and temperature sensitive. A significant decrease in the work hardening rate is observed after deformation at 77K and a strain rate of 2000/s. Coarse {110} slip traces are observed after deformation at a strain rate of 2000/s at 77K, while no slip traces were observed after deformation under all other conditions. TEM observations reveal distinct {110} slip bands after deformation at 77K and a strain rate of 2000/s.

Effect of Annealing Treatments on Strain Rate Sensitivity and Anisotropy in a Magnesium Alloy Processed by Severe Rolling

2010 ◽  
Vol 638-642 ◽  
pp. 1524-1529 ◽  
Author(s):  
J.A. del Valle ◽  
Oscar A. Ruano
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Work Hardening ◽  
Basal Slip ◽  
Plastic Anisotropy ◽  
Rate Sensitivity ◽  
Az61 Magnesium Alloy ◽  
Work Hardening Rate ◽  
R Value

The effect of annealing treatments on the evolution of the strain rate sensitivity with strain of AZ61 magnesium alloy processed by severe rolling was investigated and related to previous results on normal plastic anisotropy (r-value). The various annealing treatments produce two effects on the microstructure: grain coarsening and slight weakening of the texture. In addition, these treatments produce a noticeable decrease in strain rate sensitivity and an increase of work hardening rate that is related to the decrease of the anisotropy. It is concluded that these effects are related to an enhanced contribution of basal slip as a consequence of the microstructural changes induced by the annealing treatments.

Effects of Temperature and Strain Rate on Tensile Deformation Behavior of 9Cr-0.5Mo-1.8W-VNb Ferritic Heat-Resistant Steel

2017 ◽  
Vol 36 (9) ◽  
pp. 913-920 ◽  
Author(s):  
Xiaofeng Guo ◽  
Xiaoxiang Weng ◽  
Yong Jiang ◽  
Jianming Gong
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Work Hardening ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Tensile Deformation Behavior ◽  
Average Work ◽  
Work Hardening Rate ◽  
Effects Of Temperature ◽  
Strength And Ductility

AbstractA series of uniaxial tensile tests were carried out at different strain rate and different temperatures to investigate the effects of temperature and strain rate on tensile deformation behavior of P92 steel. In the temperature range of 30–700 °C, the variations of flow stress, average work-hardening rate, tensile strength and ductility with temperature all show three temperature regimes. At intermediate temperature, the material exhibited the serrated flow behavior, the peak in flow stress, the maximum in average work-hardening rate, and the abnormal variations in tensile strength and ductility indicates the occurrence of DSA, whereas the sharp decrease in flow stress, average work-hardening rate as well as strength values, and the remarkable increase in ductility values with increasing temperature from 450 to 700 °C imply that dynamic recovery plays a dominant role in this regime. Additionally, for the temperature ranging from 550 to 650 °C, a significant decrease in flow stress values is observed with decreasing in strain rate. This phenomenon suggests the strain rate has a strong influence on flow stress. Based on the experimental results above, an Arrhenius-type constitutive equation is proposed to predict the flow stress.

Dislocation Structures and Anomalous Yielding in Ordered Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
P. M. Hazzledine ◽  
Y. Q. Sun
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Strain Rate ◽  
Yield Stress ◽  
Work Hardening ◽  
Screw Dislocations ◽  
Ordered Alloys ◽  
Work Hardening Rate ◽  
Initial Work ◽  
Edge Dislocations

ABSTRACTThe strain, strain rate and temperature dependencies of the yield stresses of the model L12 materials Ni3Al, Ni3Ga and Co3Ti are described, as well as two associated properties, the initial work-hardening rate and the inverted creep. These mechanical properties, the electron microscope observations of <110> {111} APB coupled slip and the violations of Schmid's laws point to glissile-sessile-glissile transitions by cross slip of screw dislocations as the explanation for the yield stress anomaly. Similar explanations are probable for h.c.p. Be, B2 CoTi and tetragonal TiAl and MoSi2. A different kind of model, based on the behavior of edge dislocations is required for h.c.p. Mg, B2 CuZn and DO19 Ti3Al.

Effects of prestrain on high temperature impact properties of 304L stainless steel

2010 ◽  
Vol 25 (4) ◽  
pp. 754-763 ◽  
Author(s):  
Woei-Shyan Lee ◽  
Chi-Feng Lin ◽  
Tao-Hsing Chen ◽  
Meng-Chieh Yang
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Strain Rate ◽  
Work Hardening ◽  
Rate Sensitivity ◽  
304L Stainless Steel ◽  
Impact Properties ◽  
Work Hardening Rate ◽  
The Impact ◽  
Sensitivity Increase

The effects of prestrain, strain rate, and temperature on the impact properties of 304L stainless steel are investigated using a compressive split-Hopkinson pressure bar. The impact tests are performed at strain rates ranging from 2000 to 6000 s−1 and temperatures of 300, 500, and 800 °C using 304L specimens with prestrains of 0.15 or 0.5. The results show that the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate or decreasing temperature. As the prestrain increases, the flow stress and strain rate sensitivity increase, but the work-hardening rate decreases. The temperature sensitivity increases with an increasing strain rate, temperature, and prestrain. Overall, the effects of prestrain on the impact properties of the tested specimens dominate those of the strain rate or temperature, respectively. Finally, optical microscopy observations reveal that the specimens fracture primarily as the result of the formation of adiabatic shear bands.

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