High-temperature deformation of mullite and analysis of creep curves

2003 ◽  
Vol 18 (8) ◽  
pp. 1771-1776 ◽  
Author(s):  
H. Rhanim ◽  
C. Olagnon ◽  
G. Fantozzi ◽  
A. Azim
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Creep Behavior ◽  
Slow Crack Growth ◽  
Steady State Creep ◽  
The Other ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Steady State Creep Rate ◽  
Creep Curves

The creep behavior of mullite was studied under different stresses and in the temperature range 1200–1450 °C, and an analysis of creep curves was proposed. The study of creep behavior of mullite at high temperatures clearly indicates that this material exhibits concurrent creep and slow crack growth. An effective transition stress exists at each temperature. The analysis takes account of the total creep curve; in particular, the primary and stationary stages. It is now possible to determine by extrapolation the steady-state creep rate for specimens that break in the transient domain during tests. Thus, one can verify the influence of the stress on the steady-state creep rate over a wide stress range. On the other hand, this analysis clearly indicates the existence of two values of the activation energy around 1300 °C; this suggests a change of creep mechanism at this temperature.

Creep behavior of eutectic Sn–Ag lead-free solder alloy

2002 ◽  
Vol 17 (11) ◽  
pp. 2897-2903 ◽  
Author(s):  
M. L. Huang ◽  
L. Wang ◽  
C. M. L. Wu
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Creep Behavior ◽  
Absolute Temperature ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Straight Line ◽  
The Matrix ◽  
Dislocation Pipe ◽  
Free Solder

Precipitation-strengthened tin-based eutectic Sn–3.5 Ag alloy was investigated for its creep behavior at three temperatures ranging from 303 to 393 K, under the tensile stress range of σ/E = 10−4 to 10−3. The steady-state creep rates cover seven orders of magnitude (10−3 to 10−9 s−1). The initial microstructure was found to have Ag3Sn intermetallic compound finely dispersed in the matrix of β–Sn. By incorporation of a threshold stress, σth, into the analysis, the creep data of eutectic Sn–Ag at all temperatures can be fitted by a single straight line with a slope of seven after normalizing the steady-state creep rate and the effective stress, indicating that the creep rates are controlled by the dislocation-pipe diffusion in the Sn matrix. The steady-state creep rate, , can then be expressed as , where QC is the creep activation energy, G is the temperature-dependent shear modulus, b is Burger's vector, R is the universal gas constant, T is the absolute temperature, σ is the applied stress, A is a material-dependent constant, and , in which σOB is the Orowan bowing stress and kR is the relaxation factor.

Creep Contributes to the Fatigue Behavior of Bovine Trabecular Bone

1998 ◽  
Vol 120 (5) ◽  
pp. 647-654 ◽  
Author(s):  
S. M. Bowman ◽  
X. E. Guo ◽  
D. W. Cheng ◽  
T. M. Keaveny ◽  
L. J. Gibson ◽  
...  
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Trabecular Bone ◽  
Fatigue Behavior ◽  
Slow Crack Growth ◽  
Hysteresis Loops ◽  
Steady State Creep ◽  
Time To Failure ◽  
Steady State Creep Rate ◽  
Creep Tests

Repetitive, low-intensity loading from normal daily activities can generate fatigue damage in trabecular bone, a potential cause of spontaneous fractures of the hip and spine. Finite element models of trabecular bone (Guo et al., 1994) suggest that both creep and slow crack growth contribute to fatigue failure. In an effort to characterize these damage mechanisms experimentally, we conducted fatigue and creep tests on 85 waisted specimens of trabecular bone obtained from 76 bovine proximal tibiae. All applied stresses were normalized by the previously measured specimen modulus. Fatigue tests were conducted at room temperature; creep tests were conducted at 4, 15, 25, 37, 45, and 53°C in a custom-designed apparatus. The fatigue behavior was characterized by decreasing modulus and increasing hysteresis prior to failure. The hysteresis loops progressively displaced along the strain axis, indicating that creep was also involved in the fatigue process. The creep behavior was characterized by the three classical stages of decreasing, constant, and increasing creep rates. Strong and highly significant power-law relationships were found between cycles-to-failure, time-to-failure, steady-state creep rate, and the applied loads. Creep analyses of the fatigue hysteresis loops also generated strong and highly significant power law relationships for time-to-failure and steady-state creep rate. Lastly, the products of creep rate and time-to-failure were constant for both the fatigue and creep tests and were equal to the measured failure strains, suggesting that creep plays a fundamental role in the fatigue behavior of trabecular bone. Additional analysis of the fatigue strain data suggests that creep and slow crack growth are not separate processes that dominate at high and low loads, respectively, but are present throughout all stages of fatigue.

On Statistical Properties of High Temperature Creep Rupture Data in STS304 Stainless Steels

2006 ◽  
Vol 326-328 ◽  
pp. 553-556
Author(s):  
Seon Jin Kim ◽  
Yu Sik Kong ◽  
Young Jin Roh ◽  
Won Taek Jung
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Stainless Steels ◽  
Probability Distributions ◽  
Creep Rupture ◽  
Steady State Creep ◽  
Rupture Time ◽  
Steady State Creep Rate ◽  
Rupture Data ◽  
Short Time

This paper deals with the statistical properties of short time creep rupture characteristic values (for example, creep rupture time, steady state creep rate, total creep rate, initial strain, etc.) in STS304 stainless steels. From short time creep rupture tests performed by constant stresses at three different elevated temperatures 600, 650 and 700, the scatter and probability distributions were investigated for rupture time, total creep rate, steady state creep rate, initial strain, and others. The effect of temperature on the statistical scatter of rupture time was the smallest at 700. The effect of stress on the statistical scatter of rupture time was smaller with increasing stresses. The probability distributions of short time creep rupture data were well followed 2-parameter Weibull.

On Creep Rupture Characteristics in STS304 Stainless Steels

2006 ◽  
Vol 326-328 ◽  
pp. 1309-1312
Author(s):  
Seon Jin Kim ◽  
Yu Sik Kong ◽  
Young Join Noh ◽  
Won Taek Jung ◽  
Sang Woo Kwon
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Stress Exponent ◽  
Stainless Steels ◽  
Elevated Temperatures ◽  
Creep Rupture ◽  
Steady State Creep ◽  
Rupture Time ◽  
Steady State Creep Rate ◽  
Creep Stress

In this study, the creep rupture tests of STS304 stainless steels were investigated at three different elevated temperatures of 600, 650 and 700 under the constant creep stresses. Creep rupture characteristics such as creep stress, creep rupture time, steady state creep rate and so on were evaluated. The behaviors of creep rate curve and initial strain are compared at three different elevated temperatures. The stress exponent (n) at 600, 650 and 700 based on steady state creep rate showed 22.5, 20.6 and 11.4 respectively. By increasing the temperature, the stress exponent is decreased. At the temperature of 700, the lowest stress exponents are shown and this behavior is also observed in the case of stress exponent based on rupture time. The creep life prediction by LMP method is presented and the equation of this result is as follows: T(logtr+20)=-0.005152-14.56+24126.

Coupled modeling of steady-state creep rate and creep rupture strength for metals

2008 ◽  
Vol 40 (4) ◽  
pp. 411-418
Author(s):  
N. A. Veklich ◽  
A. M. Lokoshchenko ◽  
P. N. Veklich
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Steady State Creep ◽  
Creep Rupture Strength ◽  
Steady State Creep Rate ◽  
Coupled Modeling

A Parametric Approach to Cyclic Creep

1976 ◽  
Vol 43 (1) ◽  
pp. 28-32
Author(s):  
V. M. Radhakrishnan
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Maximum Stress ◽  
Pure Aluminum ◽  
Cyclic Creep ◽  
Steady State Creep ◽  
Strain Accumulation ◽  
Parametric Approach ◽  
Steady State Creep Rate ◽  
Reference Stress

Investigations have been carried out to study the effect of oscillating stress on the strain accumulation in pure aluminum at elevated temperature. The creep rate under the oscillating stress has been found to increase with increasing value of the alternating component of the stress and is somewhat higher than the steady-state creep rate corresponding to the maximum stress, in the range of temperature used. The rupture time is inversely proportional to the cyclic creep rate. A model for obtaining the reference stress has been proposed and based on the data obtained, a parametric approach is presented.

On the effective stress dependence of the steady-state creep rate in SnPb eutectic

1974 ◽  
Vol 21 (2) ◽  
pp. K89-K91 ◽  
Author(s):  
R. Horiuchi ◽  
A. B. El-Sebai ◽  
M. Otsuka
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Effective Stress ◽  
Steady State Creep ◽  
Stress Dependence ◽  
Steady State Creep Rate

scholarly journals A statistical model to predict the steady-state creep rate

2014 ◽  
Vol 63 (2) ◽  
pp. 028101
Author(s):  
Li Jing-Tian ◽  
Wang Jian-Lu ◽  
Zhang Bang-Qiang ◽  
Rong Xi-Ming ◽  
Ning Xi-Jing
Keyword(s):  
Steady State ◽  
Creep Rate ◽  
Statistical Model ◽  
Steady State Creep ◽  
Steady State Creep Rate
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