Some New Approaches in the Analysis of High-Temperature Deformation

1976 ◽  
Vol 98 (1) ◽  
pp. 2-8 ◽  
Author(s):  
D. A. Woodford
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Constant Load ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Range ◽  
Creep Tests ◽  
Stress Strain ◽  
Creep Analysis ◽  
Good Agreement

Creep tests on two heats of a CrMoV steel at 811K (1000°F) are analyzed using a new graphical procedure to solve the equation σ = C(t) H(ε). This enables prediction of both constant load and constant stress creep behavior at different stresses within the range examined which included tests lasting in excess of 10,000 hr. An analytical solution of the equation is also described and used to generate isochronous stress-strain curves. Attempts to predict the response in relaxation and constant strain rate tests where the load is continuously changing are described. Reasonable agreement was obtained in the former type of test using a total strain rule, which assumes a unique relationship between stress, strain and time, when the stress range covered was within the range used in the creep analysis. For constant strain rate testing, where a much broader stress range was involved, it was necessary to use incremental analysis to achieve good agreement between predicted and experimental curves up to about 2 percent strain.

Numerical Simulation of Hot Forging for the Disc of Superalloy GH4169

2011 ◽  
Vol 328-330 ◽  
pp. 1598-1601
Author(s):  
Yan Shu Zhang ◽  
Xiao Fei Liu
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Volume Fraction ◽  
Hot Forging ◽  
Pure Titanium ◽  
Constant Strain Rate ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Strain ◽  
Average Grain Size

In this paper, the hot deformation behavior of GH4169 superalloy were investigated at temperature of 900-1020°C and at strain rate of 0.001-0.1up to a 60% height reduction of the sample using isothermal constant strain rate compression tests on process annealed material. The high temperature deformation behaviour of pure titanium was characterized based on an analysis of the stress–strain curves The proposed constitutive equation and the stress-strain curves were implanted into DEFORM2D, a hot forging process for the disc of GH4169 was simulated, and the micro-variable, recrystallized volume fraction, average grain size, recrystallized grain size and etc., were plotted with a contoured figure. According to the comparision between the experimental and predicted result, the absolute error between them is acceptable. The method for microstructure prediction will be significant to the engineering.

On the High Temperature Creep and Relaxation Behaviour of Zr-based Bulk Metallic Glasses

2000 ◽  
Vol 644 ◽  
Author(s):  
B. S. S. Daniel ◽  
M. Heilmaier ◽  
A. Reger-Leonhard ◽  
J. Eckert ◽  
L. Schultz
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Behaviour ◽  
True Strain ◽  
Constant Load ◽  
Strain Rate Range ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Creep Tests ◽  
True Strain Rate

AbstractCreep tests under constant load as well as constant true strain rate were carried out at near the glass transition temperatures (Tg) to study the time dependent flow behaviour of a Zr-based bulk metallic glass (BMG). The strain rate - stress relation over a wide strain rate-range (10-7 to 10-2 s-1) was established for different temperatures. The high temperature deformation behaviour is explained on the basis of stress induced creation of free volume versus diffusion controlled annihilation processes. It was found that the creep kinetics near Tg is controlled by the mobility of atoms with an activation energy value Q =410kJ/mol.

High Temperature Plastic Behaviour of Icosahedral AlCuFe Quasicrystals.

2000 ◽  
Vol 643 ◽  
Author(s):  
Jan Fikar ◽  
Joël Bonneville ◽  
Nadine Baluc ◽  
Pierre Guyot
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Friction Stress ◽  
Dislocation Model ◽  
Compression Tests ◽  
Creep Tests ◽  
Flow Strength ◽  
Stress Strain ◽  
Softening Effect ◽  
Dislocation Interaction

AbstractIcosahedral AlCuFe poly-quasicrystalline specimens were deformed in constant strain rate compression tests at temperatures ranging between 300K - 1020K. Below nearly 0.7 Tm (Tm is the melting temperature) the specimens were brittle. Above the brittle-to-ductile transition temperature, after the elastic stage the stress-strain curves exhibit a marked yield-point followed by a stage of strain softening only. Transient creep tests were performed at different given stress/strain levels after interrupting the constant strain-rate deformation tests. After the transient tests, the flow strength of the specimens was investigated anew at constant strain rate. The results are interpreted in the framework of a dislocation model, where two effects opposing dislocation movement are considered: firstly, the usual elastic dislocation interaction, yielding a work-hardening contribution, and, secondly, a friction stress specific to the quasiperiodic lattice, leading to a softening effect.

Dislocation Creep in Al-22.2, 53.6 and 101 at.ppm Fe Solid Solution Alloys

2014 ◽  
Vol 922 ◽  
pp. 749-754
Author(s):  
K. Takeshima ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Creep Resistance ◽  
Dislocation Creep ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Range ◽  
Creep Tests ◽  
Ultra High Purity ◽  
Dominant Deformation Mechanism

Creep tests of ultra-high-purity (99.999%) Al and Al-22.2, 53.6, 101 at.ppm Fe solid solution alloys were conducted at 773 K in the stress range of 2-6 MPa in order to investigate effect of solute Fe on high temperature deformation of Al. Creep resistance was enhanced by addition of Fe in solid solution. The stress exponents of the samples exhibited values of about 5, which indicate that climb-controlled dislocation creep was dominant deformation mechanism. It could be suggested that Fe atoms segregating in dislocations due to the strong interaction between solute Fe atoms and the dislocation enhanced the creep resistance.

An Empirical Creep Law From a Single Test

1962 ◽  
Vol 84 (2) ◽  
pp. 236-238
Author(s):  
Iain Finnie
Keyword(s):  
Strain Rate ◽  
Creep Test ◽  
Constant Load ◽  
Constant Stress ◽  
Single Test ◽  
Creep Tests ◽  
Stress Strain ◽  
Strain And Strain Rate ◽  
Single Constant

A method is described by which an empirical creep law, relating stress, strain, and strain rate, may be obtained from a single constant-load creep test. An example to illustrate the method is given, and the empirical creep law is compared with the results of several constant stress creep tests.

High Temperature Deformation Mechanical Model and Processing Map of Ti-6Al-2Zr-1Mo-1V Alloy

2011 ◽  
Vol 199-200 ◽  
pp. 1988-1992
Author(s):  
Yao Ning Wang ◽  
Xi Cheng Zhao ◽  
Hong Zhou Ma
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Power Dissipation ◽  
Processing Map ◽  
Constant Strain Rate ◽  
Stress Index ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Peak Efficiency ◽  
Lower Temperature

Based on the high temperature compression simulation experiments, the mechanical behavior of Ti-6AI-2Zr-1Mo-1V alloy were studied over the range of temperature from 850°C to 1100°C , strain rate from 0.01 to 10s-1. The results show that the flow stress reduces with temperature increasing at the constant strain rate and increases rapidly with strain rate increasing at the constant temperature. The stress index n and deformation activation energy Q is respectively 7.0874 and 610.463 kJ/mol at 850-950°C . While at 950-1100°C , n is 4.7324 and Q is 238.030 kJ/mol. From the obtained processing map, it is found that two unstable regions present at the lower temperature or higher strain rate and two optimum regions in hot deformation process. The unstable zones are 850-950°C , 0.001-0.008s-1of strain rate, and 940-1030°C , 2-10s-1of strain rate respectively. In the optimum zone with the temperature range of 1060-1100°C , strain rate of 0.05-0.65s-1, and the peak efficiency of power dissipation of about 0.42; while in the other zone with the deformation temperature 890-940°C , strain rate of 0.06-0.18s-1, and the peak efficiency of power dissipation of about 0.33.

An Experimental Study on the Effect of Prior Plastic Straining on Creep Behavior of 304 Stainless Steel

1993 ◽  
Vol 115 (2) ◽  
pp. 200-203 ◽  
Author(s):  
Z. Xia ◽  
F. Ellyin
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Rate ◽  
Creep Behavior ◽  
Test Procedure ◽  
Constant Strain Rate ◽  
304 Stainless Steel ◽  
Creep Model ◽  
Plastic Strain Rate ◽  
Creep Tests

Constant strain-rate plastic straining followed by creep tests were conducted to investigate the effect of prior plastic straining on the subsequent creep behavior of 304 stainless steel at room temperature. The effects of plastic strain and plastic strain-rate were delineated by a specially designed test procedure, and it is found that both factors have a strong influence on the subsequent creep deformation. A creep model combining the two factors is then developed. The predictions of the model are in good agreement with the test results.

High Temperature Deformation Mechanism Maps of NiAl

2004 ◽  
Vol 449-452 ◽  
pp. 57-60
Author(s):  
I.G. Lee ◽  
A.K. Ghosh
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Calculation Method ◽  
Deformation Behavior ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
Temperature Strain

In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.

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