Effect of Stress on Creep at High Temperatures

1957 ◽  
Vol 24 (2) ◽  
pp. 207-213
Author(s):  
H. Laks ◽  
C. D. Wiseman ◽  
O. D. Sherby ◽  
J. E. Dorn
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
High Temperature ◽  
Creep Rate ◽  
Pure Aluminum ◽  
Dislocation Climb ◽  
Experimental Investigations ◽  
High Temperature Creep ◽  
Self Diffusion ◽  
Temperature Creep

Abstract Experimental investigations on pure aluminum and its dilute solid-solution alloys revealed that the high-temperature creep rate ϵ̇ is related to the stress σ by ϵ̇ ∼ σn for low stresses and ϵ̇ ∼ eBσ for high stresses where n and B are constants independent of the creep strain and temperature. According to a preliminary dislocation-climb model for high-temperature creep, the activation energy for creep is that for self-diffusion, the effect of stress on the creep rate depends on the number of active Frank-Read sources, and the rate of climb depends on the structure as determined by the pattern of climbing dislocations. Many of the experimental observations on high-temperature creep can be accounted for by this model.

Interface Controlled Diffusional Creep of Cu + 2.8 at.% Co Solid Solution

2012 ◽  
Vol 322 ◽  
pp. 33-39 ◽  
Author(s):  
Sergei Zhevnenko ◽  
Eugene Gershman
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Creep Behavior ◽  
Pure Copper ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Temperature Range ◽  
Different Temperatures

High-temperature creep experiments were performed on a Cu-2.8 ат.% Co solid solution. Cylindrical foils of 18 micrometers thickness were used for this purpose. Creep tests were performed in a hydrogen atmosphere in the temperature range of about from 1233 K to 1343 K and at stresses lower than 0.25 MPa. For comparison, a foil of pure copper and Cu-20 at.% Ni solid solution were investigated on high temperature creep. Measurements on the Cu foil showed classical diffusional creep behavior. The activation energy of creep was defined and turned out to be equal 203 kJ/mol, which is close to the activation energy of bulk self-diffusion of copper. There was a significant increase in activation energy for the Cu-20 at.% Ni solid solution. Its activation energy was about 273 kJ/mol. The creep behavior of Cu-Co solid solution was more complicated. There were two stages of diffusional creep at different temperatures. The extremely large activation energy (about 480 kJ/mol) was determined at relatively low temperature and a small activation energy (about 105 kJ/mol) was found at high temperatures. The creep rate of Cu-Co solid solution was lower than that of pure copper at all temperatures. In addition, the free surface tension of Cu-2.8 ат.% Co was measured at different temperatures from 1242 K to 1352 K. The surface tension increases in this temperature range from 1.6 N/m to 1.75 N/m. There were no features on the temperature dependence of the surface tension.

High-Temperature Creep of Equimolecular NiOCoO Solid Solution

1984 ◽  
Vol 85 (2) ◽  
pp. 445-448 ◽  
Author(s):  
A. Dominguez-Rodbiguez ◽  
J. Cabbeba-Uaño ◽  
R. Marquez ◽  
J. Castaing
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
High Temperature Creep ◽  
Temperature Creep

MTEK 25-35MA

Alloy Digest ◽  
2016 ◽  
Vol 65 (9) ◽  
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Creep Strength ◽  
Heat Treating ◽  
Casting Alloy ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Temperature Performance

Abstract MTEK 25-35MA is a solid solution microalloyed Fe-Ni-Cr-Nb casting alloy with good high-temperature creep strength. It is intended for use in pyrolysis cracker furnaces. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: SS-1249. Producer or source: MetalTek International. Originally published July 2016, revised September 2016.

Effect of Variation in Grain Size on High Temperature Creep Test of Fe-Ni-Cr Alloy

2013 ◽  
Vol 845 ◽  
pp. 51-55
Author(s):  
Esah Hamzah ◽  
Maureen Mudang ◽  
Muhammad Adil Khattak
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Creep Rate ◽  
Creep Damage ◽  
Grain Boundary Sliding ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Nickel Based Superalloy ◽  
Solution Treated ◽  
Incoloy 800H

Fe-Ni-Cr or known as Incoloy 800H and Haynes HR120 is a solid solution strengthened iron-nickel based superalloy which is extensively used in high temperature and corrosive environment. The effect of grain size in creep strength and creep rate comes through the grain boundary sliding and grain boundaries as barrier mechanism. This paper describes the effect of microstructural variation of Fe-Ni-Cr on the high temperature creep properties. The materials were heat treated at temperature 1050°C and 1200°C followed by water quenching process. The grain size of the samples of Incoloy 800H is 95.47μm for as-received, 122.81μm for solution treated at 1050°C and 380.95μm for solution treated at 1200°C. And the grain size of the samples of Haynes HR120 is 53.45μm for as-received, 61.50μm for solution treated at 1050°C and 158.27μm for solution treated at 1200°C. The creep damage investigation was carried out in the three different grain sizes of Fe-Ni-Cr superalloy at 900°C with stress at 100MPa. Rectangular section forms of specimens are used in the research. In all the tests conducted, the creep curves show primary, secondary and tertiary stages. The creep fracture surface were characterised by using scanning electron microscope. It was found that larger grain size results in lower creep rate for alloy Haynes HR120 but inverse result showed on alloy Incoloy 800H.

High Temperature Creep Behavior of Zn-1.0Cu-0.2Ti Alloy

2011 ◽  
Vol 287-290 ◽  
pp. 769-776 ◽  
Author(s):  
Lai Rong Xiao ◽  
Xi Min Zhang ◽  
Yan Wang ◽  
Wei Li ◽  
Quan Sheng Sun ◽  
...  
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Creep Rate ◽  
Grain Boundary ◽  
Testing Machine ◽  
Steady State Creep ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Steady State Creep Rate ◽  
Temperature Creep

In the present work, Zn-1.0Cu-0.2Ti alloy was prepared by melt casting and extruding processes. High temperature creep property of the alloy was determined using electronic creep relaxation testing machine. Microstructures of the alloy before and after creep test were observed and its high temperature creep mechanism was discussed. The results show that the steady-state creep rate of the alloy increases with temperature and stress. The logarithm of steady-state creep rate (ln) shows a linearity relationship with the logarithm of the stress (lnσ) and reciprocal of temperature (1/T). The stress exponent and apparent activation energy for creep have been determined to be 5.10 and 83.7 kJ/mol, separately. The predominant mechanism is mainly self-diffusional creep. The second phases on the grain boundary can block the slip of grain boundary and dislocation motion which can improve creep resistance of the alloy.

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