High-Temperature Deformation of Yba2Cu307-8 With Ag Additions

1989 ◽  
Vol 169 ◽  
Author(s):  
J.L. Routbort ◽  
K.C. Goretta ◽  
J.P. Singh
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Temperature ◽  
Flow Stress ◽  
Compressive Strain ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Steady State Flow ◽  
Ag Additions

AbstractThe steady‐state flow stress of YBa2Cu3O7‐δ containing 15 to 30 vol.% Ag has been measured in air at nearly constant compressive strain rates between 5 x 10‐6 and 1 x 10‐4 s‐1 from 830 to 900°C. Addition of Ag dramatically decreases the flow stress compared to that of the pure superconductor, but the stress exponents and the activation energy for deformation remain unchanged.

Modelling Dynamic Recovery and Recrystallization of Metals by a New Non-Equilibrium Thermodynamics Approach

2007 ◽  
Vol 558-559 ◽  
pp. 517-522
Author(s):  
Ming Xin Huang ◽  
Pedro E.J. Rivera-Díaz-del-Castillo ◽  
Sybrand van der Zwaag
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Flow Stress ◽  
Dislocation Density ◽  
Dynamic Recovery ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Equilibrium Thermodynamics ◽  
Burgers Vector ◽  
Non Equilibrium

A non-equilibrium thermodynamics-based approach is proposed to predict the dislocation density and flow stress at the steady state of high temperature deformation. For a material undergoing dynamic recovery and recrystallization, it is found that the total dislocation density can be expressed as ( )2 ρ = λε& b , where ε& is the strain rate, b is the magnitude of the Burgers vector and λ is a dynamic recovery and recrystallization related parameter.

Dynamic Deformation Response of G33 Steel under High Temperature

2015 ◽  
Vol 782 ◽  
pp. 61-70
Author(s):  
You Jing Zhang ◽  
Hong Nian Cai ◽  
Xing Wang Cheng ◽  
Shuang Zan Zhao
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Shear Bands ◽  
Shear Zones ◽  
Adiabatic Shear ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Adiabatic Shear Bands

The high temperature deformation and fracture behavior of ultra-high strength G33 steel under high strain rate compression are investigated by means of a split Hopkinson p ressure bar. Impact tests are performed at strain rates of 1000/s and 2200/s and at temperatures ranging from 25°C to 700°C. The SEM and TEM techniques are also used to analyze the microstructure evolution of the adiabatic shear band (ASB) and fracture characteristics of the deformed specimens at high temperature. The experimental results indicate that the flow stress of G33 steel is significantly dependent on temperatures and strain rates. The flow stress of G33 steel increases with the increase of strain rates, but decreases with the increase of temperatures. The strain rate sensitivity is more pronounced at the low temperature of 25°C. In addition, G33 steel is more liable to fracture at high temperatures than at 25°C. Observations of microstructure show two well-developed symmetric parabolic adiabatic shear bands on the longitudinal cross-section of the cylindrical specimen deformed at the temperature of 700°C and at the strain rate of 2200/s. Within the ASB, the width of the fine equiaxed grain structure is about 7μm. The size of those equiaxed grains is approximately 100nm. The fracture analysis results indicate that the ASBs are the predominant deformation and the specimens fracture along adiabatic shear bands. The fracture surfaces of the deformed G33 steel specimens are characterized by two alternating zones: rough dimple zone and relatively smooth shear zone. Further observations reveal that smooth shear zones consist of severely sheared dimples.

Deformation Mechanism Maps for Al-Cu-Mg Alloys Micro-Alloyed with Tin

2011 ◽  
Vol 410 ◽  
pp. 283-286
Author(s):  
P.S. Robi ◽  
Sanjib Banerjee ◽  
A. Srinivasan
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Base Alloy ◽  
Mg Alloy ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Microstructural Investigation

High temperature deformation behavior of Al–5.9%Cu–0.5%Mg alloy and Al–5.9%Cu–0.5%Mg alloy containing 0.06 wt.% of Sn was studied by hot compression tests at various temperatures and strain rates. Addition of trace amounts of Sn into the Al–Cu–Mg alloy system resulted in a significant increase of flow stress for all conditions of temperature and strain rate. 100% and 89% of the flow stress values during hot deformation could be predicted within ± 10% deviation values for the aluminum alloys with and without Sn content, respectively, by artificial neural network (ANN) modeling. From the deformation mechanism maps and microstructural investigation, the safe process regimes for hot working of the base alloy was identified to be at (i) very low strain rate (< 0.003 s−1) at temperature < 450 °C, and (ii) high temperature (> 400 °C) with strain rate > 0.02 s−1. For the micro-alloyed alloy, it was at low strain rates (< 0.01 s-1) for the entire temperature range studied. Flow softening for both alloys was observed to be at low strain rates and was identified to be due to dynamic recrystallization (DRX). The metallurgical instability during deformation was identified due to shear band formation and/or inter-crystalline cracking.

The Deformability of Fe-Ni Superalloy during High Temperature Deformation

2016 ◽  
Vol 246 ◽  
pp. 221-224
Author(s):  
Kazimierz J. Ducki ◽  
Kinga Rodak ◽  
Lilianna Wojtynek
Keyword(s):  
Activation Energy ◽  
Plastic Deformation ◽  
High Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Flow Curves ◽  
Plastic Properties ◽  
Hot Torsion ◽  
Total Fracture

The influence of initial soaking and parameters of plastic deformation on the deformability of A-286 superalloy have been presented. The hot-torsion tests were executed at constant strain rates of 0.1 and 1.0 s-1, at testing temperatures in the range 900-1150°C and were conducted until total fracture of the samples. Plastic properties of the alloy were characterized by worked out flow curves and the temperature relationships of flow stresses and strain limits. Activation energy for hot working Q was assessed for the alloy after two variants of previous heating, i.e. 1100°C/2 h and 1150°C/2 h.

High Temperature Deformation of Wrought Zn-Containing Magnesium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1482-1487 ◽  
Author(s):  
S. Spigarelli ◽  
Mohamad El Mehtedi ◽  
D. Ciccarelli ◽  
Menachem Bamberger ◽  
Giuseppe Cupitò ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Flow Stress ◽  
Magnesium Alloys ◽  
Temperature Response ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Lower Strength ◽  
The Difference ◽  
Zn Alloys

The high temperature response in torsion and creep of two extruded Mg-Zn alloys was investigated in the present study. The alloy 0 (Mg-2Zn-1Mn) was found to exhibit a lower strength than the alloy 2 (Mg-0.55Zn-0.79Mn-0.75Al-0.17Ca), even if the activation energy for creep was similar for both materials (170-180 kJ/mol). The difference in flow stress was here preliminarily attributed to the precipitation of fine Al2Ca particles.

Characterization of High Temperature Deformation Behavior of BFe10-1-2 Cupronickel Alloy Using Orthogonal Analysis

2017 ◽  
Vol 36 (7) ◽  
pp. 701-710
Author(s):  
Jun Cai ◽  
Kuaishe Wang ◽  
Xiaolu Zhang ◽  
Wen Wang
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Statistical Parameters ◽  
Orthogonal Analysis

AbstractHigh temperature deformation behavior of BFe10-1-2 cupronickel alloy was investigated by means of isothermal compression tests in the temperature range of 1,023~1,273 K and strain rate range of 0.001~10 s–1. Based on orthogonal experiment and variance analysis, the significance of the effects of strain, strain rate and deformation temperature on the flow stress was evaluated. Thereafter, a constitutive equation was developed on the basis of the orthogonal analysis conclusions. Subsequently, standard statistical parameters were introduced to verify the validity of developed constitutive equation. The results indicated that the predicted flow stress values from the constitutive equation could track the experimental data of BFe10-1-2 cupronickel alloy under most deformation conditions.

Constitutive Analysis of the High-Temperature Deformation Behavior of Single Phase α-Ti and α+β Ti-6Al-4V Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3607-3612 ◽  
Author(s):  
Jeoung Han Kim ◽  
Jong Taek Yeom ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Deformation Behavior ◽  
Single Phase ◽  
Volume Fraction ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Β Phase ◽  
Α Phase ◽  
Self Consistent

The high-temperature deformation behavior of the single-phase α (Ti-7.0Al-1.5V) and α + β (Ti-6Al-4V) alloy were determined and compared within the framework of self-consistent scheme at various temperature ranges. For this purpose, isothermal hot compression tests were conducted at temperatures between 650°C ~ 950°C to determine the effect of α/β phase volume fraction on average flow stress under hot-working condition. The flow behavior of α phase was estimated from the compression test results of single-phase α alloy whose chemical composition is close to that of α phase of Ti-6Al-4V alloy. On the other hand, the flow stress of β phase in Ti-6Al-4V was predicted by using self-consistent method. The flow stress of α phase was higher than that of β phase above 750°C, while the β phase revealed higher flow stress than α phase at 650°C. Also, at temperature above 750°C, the predicted strain rate of β phase was higher than that of α phase. It was found that the relative strength between α and β phase significantly varied with temperature.

Hot Working of the ZEK200 Magnesium Alloy

2008 ◽  
Vol 604-605 ◽  
pp. 212-222 ◽  
Author(s):  
S. Spigarelli ◽  
Mohamad El Mehtedi ◽  
P. Ricci
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Direct Chill ◽  
Equivalent Strain ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Torsion Testing ◽  
A Value ◽  
Complete Recrystallization

The high temperature workability of the ZEK200 Mg-alloy produced by Direct Chill casting (DC) was investigated by torsion testing between 200 and 450°C. The alloy exhibited a higher strength and a slightly lower equivalent strain to fracture than AZ31 and ZM21 produced by DC. The calculation of the constitutive equation gave a value of the activation energy for high temperature deformation close to 175 kJ/mol, in line with those calculated by following the same procedure in AZ31 and ZM21. Partial or complete recrystallization of the deformed structure was observed at 350 and 400°C respectively. Grain growth occurred after recrystallization in the samples tested at 450°C.

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