Effects of Microstructures on Strength and Fatigue Properties of Long-Term-Serviced F12 Steels

2007 ◽  
Vol 353-358 ◽  
pp. 295-298
Author(s):  
X.M. Wu ◽  
G.P. Zhang ◽  
J.Q. Zhang ◽  
W.G. Chen
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Fatigue Crack Initiation ◽  
Fatigue Properties ◽  
Degradation Mechanisms ◽  
Creep Properties ◽  
Running Time ◽  
Electron Microscopes ◽  
Term Creep

Microstructures of long-term serviced F12 steel exposed at 545 °C have been investigated by electron microscopes. The hardness of the material was measured to be correlated with the variation of the microstructures. Fatigue properties of the material with different running time were evaluated and analyzed. The experimental results show that the coarsening of the precipitated carbides along boundaries and the formation of subgrains accelerate the degradation of the long-term creep properties of the steel. Fatigue crack initiation threshold from a notch linearly deceases with increasing the running time due to the variation of the distribution and the shape of the precipitated carbides. The degradation mechanisms of the F12 steel during their long-term service at high temperature are discussed.

scholarly journals Long-Term Creep Properties of Hastelloy XR in Simulated High-Temperature Gas-Cooled Reactor Helium

1995 ◽  
Vol 32 (11) ◽  
pp. 1108-1117 ◽  
Author(s):  
Yuji KURATA ◽  
Yutaka OGAWA ◽  
Tomio SUZUKI ◽  
Masami SHINDO ◽  
Hajime NAKAJIMA ◽  
...  
Keyword(s):  
High Temperature ◽  
Creep Properties ◽  
Term Creep ◽  
High Temperature Gas

Creep Properties of Hastelloy-X Alloy for the High Temperature Gas-Cooled Reactor

2006 ◽  
Vol 326-328 ◽  
pp. 1105-1108 ◽  
Author(s):  
Woo Gon Kim ◽  
Sang Nan Yin ◽  
Woo Seog Ryu ◽  
Jong Hwa Chang
Keyword(s):  
High Temperature ◽  
Creep Data ◽  
Creep Life ◽  
Statistical Process ◽  
Hastelloy X ◽  
Creep Properties ◽  
Rupture Data ◽  
Term Creep ◽  
High Temperature Gas

The creep properties for the Hastelloy-X alloy which is one of candidate alloys for a high temperature gas-cooled reactor are presented. The creep data was obtained with different stresses at 950oC, and a number of the creep data was collected through literature surveys. All of the creep data were combined together to obtain the creep constants and to predict a long-term creep life. In the Norton’s creep law and the Monkman-Grant relationship, the creep constants, A, n, m, and m’ were obtained. Creep master curves based on the Larson-Miller parameter were presented for the standard deviations of 1σ, 2σ and 3σ. Creep life at each temperature was predicted for a longer-time rupture above 105 hours. Failure probability was also estimated by a statistical process of all the creep rupture data.

Prediction of Long-Term Creep Properties of Zirconium-2.5 % Niobium Alloy Using Wilshire Method

2021 ◽  
Vol 10 (2) ◽  
pp. 20200146
Author(s):  
Vivek Patel ◽  
R. N. Singh ◽  
Madangopal Krishnan
Keyword(s):  
Niobium Alloy ◽  
Creep Properties ◽  
Term Creep

Grades 92 and 23: Weldability Assessment and Long-Term Performances for Power Generation Applications

2008 ◽  
Vol 580-582 ◽  
pp. 383-388
Author(s):  
Emmanuel Bauné ◽  
E. Galand ◽  
B. Leduey ◽  
G. Liberati ◽  
G. Cumino ◽  
...  
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Power Plants ◽  
Product Family ◽  
Base Material ◽  
Advanced Materials ◽  
Creep Properties ◽  
Steam Parameters ◽  
Term Creep

Increased efficiency and emission reduction in modern power plants lead to the use of new advanced materials with enhanced creep strength, with the objective to increase the steam parameters of power plants. With over ten years on market and wide experience related to its use, ASTM Grade 92 is becoming one of the most required materials when high service temperatures are reached (max. 610°C). Its composition, with 9%Cr and 1.5%W, gives rise to martensitic microstructures which offer very high creep strength and long term stability. The improved weldability and creep-strength between 500 and 580°C of the low alloy ASTM Grade 23, as well as a cost advantage over higher Cr materials in this temperature range, make it one of the possible candidates to meet the stringent requirements of modern power plants. Air Liquide Welding (ALW) has optimized and distributes a complete product family for the welding of Grades 23 and 92. TenarisDalmine (TD) focused on the development of Grade 23 tubes and pipes and is working on the development of Grade 92. A deep characterization work of the microstructural evolution and long term creep performances of these high temperature resistant materials was thus undertaken by ALW and TD, in collaboration with the Centro Sviluppo Materiali (CSM). The joint characterization program consisted in the assessment of welded joints creep properties. Welded joints were produced using the gas tungsten (GTAW), shielded metal (SMAW) and submerged arc welding (SAW) processes. Mechanical and creep properties of weldments were measured both in the as welded and post weld heat treated conditions and proper WPS’s were designed in a manner such that industrial production needs were satisfied. Short term creep resistance of cross weld specimens was measured to be within the base material acceptance criteria. Long term base material and cross weld creep performance evaluation are now in progress.

Low Cycle Fatigue and Fracture Behavior of Nickel-Base Superalloy CM247LC at 760°C

2004 ◽  
Vol 449-452 ◽  
pp. 561-564 ◽  
Author(s):  
Seong Moon Seo ◽  
In Sup Kim ◽  
Chang Yong Jo
Keyword(s):  
Fatigue Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Strain Range ◽  
Initiation Site ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Fine Grained

Low cycle fatigue (LCF) behavior of coarse and fine grained superalloy CM247LC at 760°C has been investigated. Both coarse and fine grained CM247LC showed similar cyclic stress response, however, the fine grained CM247LC specimen exhibited relatively uniform and superior fatigue properties to the coarse grained one. It was found that fatigue crack initiation of the alloy was keen to the applied strain range. Fatigue crack initiated at the surface of the specimen with high strain range (∆εt≥( 0.7%) while the initiation site moved to the internal defects at low strain range (∆εt≤0.6%).

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