Minimum creep rate from primary creep using strain relaxation and recovery test

2003 ◽  
Vol 49 (12) ◽  
pp. 1145-1150 ◽  
Author(s):  
N.K. Sinha ◽  
T. Terada ◽  
P. Au
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Strain Relaxation ◽  
Primary Creep ◽  
Recovery Test

High Temperature Creep of Alpha-2 Ti-34mo1%Al Polycrystals

1994 ◽  
Vol 364 ◽  
Author(s):  
Hiroshi Oikawa ◽  
Toshihiko Fukuda ◽  
Makoto Ohtsuka
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Single Phase ◽  
Creep Condition ◽  
Primary Creep ◽  
High Temperature Creep ◽  
Creep Tests ◽  
Creep Stage ◽  
Fine Grained ◽  
Equiaxed Grains

AbstractConstant-stress compressive creep tests were carried out on an Al-rich a2 single-phase material, which had equiaxed-grains of 60μim in grain size, at 1050∼1250 K under 100∼500MPa. The type of the primary creep stage and the microstructures developed during creep depend greatly on the creep condition. The minimum creep-rate, however, can be represented by one set of parameters over the whole range of experimental condition. The stress exponent is 5.0±0.2 and the (modulus-compensated) activation energy is 360 ± 10kJ/mol. The Dorn-type plot of the minimum creep rate reveals that the normalized creep strength of fine-grained Ti-34mol%Al is not greatly different from that of disordered solid-solution hardened alloys.

An Analysis of High Temperature Metal Creep—Part I: Experimental Definition of an Alloy

1978 ◽  
Vol 100 (4) ◽  
pp. 363-370 ◽  
Author(s):  
J. H. Laflen ◽  
D. C. Stouffer
Keyword(s):  
Creep Rate ◽  
Constitutive Modeling ◽  
Minimum Creep Rate ◽  
Major Part ◽  
Primary Creep ◽  
Rate Function ◽  
Creep Tests ◽  
Load Rate ◽  
Metal Creep ◽  
Definition Of

The general objective of the research reported is to develop a constitutive theory for the elevated temperature behavior of Wrought Udiment 700. A major part of this work was to establish a data base for this material and evaluate the observed response using many of the modern approaches to constitutive modeling. The phenomenological description of the material was evaluated by a series of load rate, strain rate, and creep tests. These data clearly showed the existence of a finite primary creep rate response function similar to the minimum creep rate function. Also the concept of material stress rate coordinate is introduced to describe the change from the primary to the minimum creep rate.

Creep Constitutive Equations for 1CrMoV Bolt Material

2002 ◽  
Author(s):  
Fred V. Ellis ◽  
Robert L. Zielke
Keyword(s):  
Creep Rate ◽  
Power Law ◽  
Constitutive Equations ◽  
Minimum Creep Rate ◽  
Good Description ◽  
Primary Creep ◽  
Primary Component ◽  
Creep Equation ◽  
Statistical Measures ◽  
Rational Polynomial

Creep constitutive equations were developed for 1CrMoV bolt material using the NRIM creep data at temperatures of 450°C, 500°C and 550°C. The creep constitutive equations were those used by the ANSYS FEM stress analysis program. Three types of creep equations were developed: (1) primary, (2) secondary, and (3) primary plus secondary. The primary creep equation had a power law in stress and time with an exponential inverse temperature dependence. The secondary models for log minimum creep rate had either log stress alone or stress and log stress terms. Two primary plus secondary models were used: (1) a power law primary and (2) the rational polynomial. For the rational polynomial, the constant p was estimated as nineteen over the time to the end of primary creep. The time to end of primary creep was defined by the attainment of a low value for the ratio of the primary creep rate to minimum creep rate. The primary creep rate was calculated using the power law primary component of the power law primary plus steady state creep equation. To evaluate the fits, comparisons of calculated and observed creep curves were made as well as plots of residual in log creep strain. Based on these comparisons and the statistical measures (R2 and standard deviation), the derived creep equations were judged to be a good description of the creep behavior.

TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

1995 ◽  
Vol 53 ◽  
pp. 350-351
Author(s):  
L. A. Giannuzzi ◽  
C. A. Lewinsohn ◽  
C. E. Bakis ◽  
R. E. Tressler
Keyword(s):  
Silicon Carbide ◽  
Creep Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Primary Creep ◽  
Excess Carbon ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Carbon Core ◽  
Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

scholarly journals Effect of Low-Temperature Annealing on Creep Properties of AlSi10Mg Alloy Produced by Additive Manufacturing: Experiments and Modeling

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 179
Author(s):  
Chiara Paoletti ◽  
Emanuela Cerri ◽  
Emanuele Ghio ◽  
Eleonora Santecchia ◽  
Marcello Cabibbo ◽  
...  
Keyword(s):  
Creep Rate ◽  
Applied Stress ◽  
Minimum Creep Rate ◽  
Annealing Treatment ◽  
Constant Load ◽  
Experimental Conditions ◽  
Creep Properties ◽  
Low Temperature Annealing ◽  
Physically Based ◽  
Excellent Description

The effects of postprocessing annealing at 225 °C for 2 h on the creep properties of AlSi10Mg alloy were investigated through constant load experiments carried out at 150 °C, 175 °C and 225 °C. In the range of the experimental conditions here considered, the annealing treatment resulted in an increase in minimum creep rate for a given stress. The reduction in creep strength was higher at the lowest temperature, while the effect progressively vanished as temperature increased and/or applied stress decreased. The minimum creep rate dependence on applied stress was modeled using a physically-based model which took into account the ripening of Si particles at high temperature and which had been previously applied to the as-deposited alloy. The model was successfully validated, since it gave an excellent description of the experimental data.

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