Effect of W on Deformation Resistance of Co-Bearing 12Cr Ferrite Heat-Resistant Steel for USC Steam Turbines

2010 ◽  
Vol 650 ◽  
pp. 199-204
Author(s):  
Hui Ran Cui ◽  
Feng Sun ◽  
Lan Ting Zhang ◽  
Ai Dang Shan ◽  
Jian Sheng Wu
Keyword(s):  
Activation Energy ◽  
Tensile Tests ◽  
Deformation Resistance ◽  
Diffusion Activation Energy ◽  
Potential Candidate ◽  
Steam Turbines ◽  
Creep Tests ◽  
Self Diffusion ◽  
Heat Resistant ◽  
Arc Melting

12Cr heat resistant steels with different concentration of Co and W, while Mo equivalent (Mo+1/2W) was fixed at 1.6, were prepared by arc-melting and hot rolling. Mechanical properties were evaluated by tensile tests conducted with the strain rate 2×10-5S-1 at 575oC, 600oC and 625oC instead of time-consuming creep tests. The results show that when Co content is fixed, the steel with 1.5 wt% W is found having the best deformation resistance which is strong work hardening and slow strain softening. Apparent activation energy of the steel with 3.1 wt% Co and 1.5 wt% W is in the range of 370~413 kJ/mol, higher than those of the other steels in our study, which are close to the self-diffusion activation energy of iron (239 kJ/mol). Therefore, the steel with 3.1 % Co and 1.5% W is suggested as a potential candidate material for 625oC~650oC class USC steam turbines.

Creep Behavior of PB-Free Solders

2001 ◽  
Author(s):  
F. Hua ◽  
C. M. Garner ◽  
H. G. Song ◽  
J. W. Morris
Keyword(s):  
Activation Energy ◽  
Creep Behavior ◽  
Solder Joints ◽  
Creep Process ◽  
Diffusion Activation Energy ◽  
Air Cooling ◽  
Shear Creep ◽  
Self Diffusion ◽  
Intermetallic Particles ◽  
Stress Levels

Abstract This study reports results of shear creep behavior of four Pb-free solders, Sn-3Ag-0.5Cu, Sn-3.5Ag, Sn-0.7Cu and Sn-10In-3.1Ag at 95θC and 130θC. At the stress levels tested, all the four solders showed the stress components close or larger than 5, typical for matrix creep. The calculated activation energies for Sn-0.7Cu, Sn-3.5Ag and Sn-3Ag-0.5Cu are from 103kJ/mol to 117kJ/mol, which are very close to the pure Sn self-diffusion activation energy (107kJ/mol). It suggested that the creep process is controlled by Sn bulk self-diffusion rate. The creep activation energy for Sn-10In-3.1Ag is higher in the range of 173–193kJ/mol. The Sn-0.7Cu, Sn-3Ag-0.5Cu and Sn-10In-3.1Ag solder joints were also prepared with two different cooling rates, 3.5θC/min. (furnace-cooling) and 2.7θC/S (air-cooling) and tested at 130θC. It was observed that faster cooled solder joints have faster creep strain rates than slower cooled solder joints at the stress levels tested for all three solders, due to the fine and even distribution of intermetallic particles.

Investigation on Creep Mechanisms of Alloy 709

2017 ◽  
Author(s):  
Abdullah S. Alomari ◽  
Nilesh Kumar ◽  
Korukonda L. Murty
Keyword(s):  
Activation Energy ◽  
Stress Exponent ◽  
Tensile Tests ◽  
Lattice Diffusion ◽  
Creep Tests ◽  
True Activation Energy ◽  
Sodium Fast Reactor ◽  
Safety And Reliability ◽  
Power Law Creep ◽  
Gen Iv

To improve efficiency, safety, and reliability of nuclear reactors, structural materials for Gen-IV reactors are being designed and developed. Alloy 709, a 20Cr-25Ni austenitic stainless steel, has superior mechanical properties to be a preferred candidate material for Sodium Fast Reactor structural application. Creep tensile tests were performed at temperatures of 700 °C, 725 °C and 750 °C and range of stresses from 100 MPa to 250 MPa. The apparent stress exponent and activation energy were found to be 10.3±0.4 and 368.6±14.7 kJ/mol. Linear extrapolation method was used to rationalize the higher stress exponent and activation energy relative to the mechanism in power law creep yielding to a true stress exponent of 7.1 ± 0.3 and a true activation energy of 277 ± 12.8 kJ/mol which is close to the lattice diffusion of iron in Fe-20Cr-25Ni. Hence, the lattice diffusion controlled dislocation climb process is believed to be the rate controlling creep deformation mechanism in this range of stresses and temperatures. The appropriate constitutive equation was developed based on the results; however, microstructural evaluations are under investigation to confirm the rate controlling mechanism. In addition, creep tests at higher temperatures and lower stresses are being conducted to extend the stress and strain-rate ranges to observe possible transition in creep mechanism.

Effect of alloying on the self-diffusion activation energy in γ-iron

2011 ◽  
Vol 53 (11) ◽  
pp. 2194-2200 ◽  
Author(s):  
A. A. Vasilyev ◽  
S. F. Sokolov ◽  
N. G. Kolbasnikov ◽  
D. F. Sokolov
Keyword(s):  
Activation Energy ◽  
The Self ◽  
Diffusion Activation Energy ◽  
Self Diffusion ◽  
Diffusion Activation ◽  
Effect Of Alloying

Compressive Behavior of Extruded SiCw/AZ91 at Temperatures close to and above the Solidus of the Matrix Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 827-830 ◽  
Author(s):  
Wei Min Gan ◽  
Ming Yi Zheng ◽  
S.B. Li ◽  
Kun Wu
Keyword(s):  
Activation Energy ◽  
Rate Sensitivity ◽  
Matrix Alloy ◽  
Deformation Energy ◽  
Diffusion Activation Energy ◽  
Self Diffusion ◽  
Deformation Activation Energy ◽  
The Matrix ◽  
Deformation Behaviors ◽  
High Strain Rate Sensitivity

Compressive deformation behaviors of extruded SiCw/AZ91 were investigated in Gleeble-1500 thermal simulator at temperatures from 743 K to 783 K and strain rates from 6.4×10-2 s-1 to 1.0×101s-1. Results showed that high strain rate sensitivity (~0.5) occurred during compression; deformation activation energy normalized by threshold stress was higher than the lattice self-diffusion activation energy of magnesium. Dynamic recovery (DRV) and dynamic recrystallization (DRX) took place during compression, which refined the grains. The increase of deformation energy was attributed to non-basal planes slip and climbing of dislocations and also the presence of liquid phase.

Static and cyclic creep behavior of in situTiB2 particulate reinforced aluminum composite

1999 ◽  
Vol 14 (12) ◽  
pp. 4541-4550 ◽  
Author(s):  
Z. Y. Ma ◽  
S. C. Tjong ◽  
S. X. Li
Keyword(s):  
Activation Energy ◽  
Stress Exponent ◽  
Cyclic Creep ◽  
Creep Tests ◽  
Aluminum Composite ◽  
Self Diffusion ◽  
True Activation Energy ◽  
Static Creep ◽  
Particulate Reinforced

Static and cyclic creep tests of Al–15 vol% TiB2in situ composite were carried out at 573–623 K. The values of apparent stress exponent and activation energy for cyclic creep of the composite were much higher than that for static creep. Furthermore, the cyclic creep rate tended to decrease with increasing percentage of unloading amount but was independent of the loading frequencies under the frequency ranges investigated. Finally, the true stress exponent of the composite was equal to 8, and the true activation energy was close to the value for the lattice self-diffusion of aluminum by incorporating a threshold stress for the analysis.

Sign in / Sign up

Export Citation Format

Share Document