Fatigue-crack initiation in IMI 829 caused by high-temperature fretting

1983 ◽  
Vol 18 (2) ◽  
pp. 493-502 ◽  
Author(s):  
M. M. Hamdy ◽  
B. Noble ◽  
R. B. Waterhouse
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Crack Initiation ◽  
Fatigue Crack Initiation

Thermal Fatigue Crack Initiation of Laser Deposited High-temperature Titanium Alloy Ti60A in 20–700 °C

2013 ◽  
Vol 32 (4) ◽  
pp. 331-337 ◽  
Author(s):  
A.L. Zhang ◽  
D. Liu ◽  
H.M. Wang
Keyword(s):  
Titanium Alloy ◽  
Fatigue Crack ◽  
High Temperature ◽  
Crack Initiation ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Thermal Fatigue Crack ◽  
Fatigue Process ◽  
Thermal Fatigue Cracks

AbstractThermal fatigue damage of high-temperature titanium alloys is of great concern for severe temperature-fluctuating environment, and the thermal fatigue crack initiation stage plays a crucial role in thermal fatigue life. In present study, thermal fatigue tests keeping 55 seconds at 700 °C followed by water cooling 15 seconds at 20 °C were performed for the laser deposited high-temperature titanium alloy Ti60A (Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si). Thermal fatigue cracks initiate after 800 thermal fatigue cycles with a length of 20 µm. Subsequently numerous cracks grow to 500 µm and cause severe degradation after 1000 cycles. To investigate the crack initiation behavior, microstructural changes during thermal fatigue process were examined by OM, SEM, EPMA and TEM. Thermal fatigue cracks initiate preferably at grain boundaries, α/β interfaces, microvoids, and abnormal coarsened α produced by oxygen interstitial solution. Mechanisms of thermal fatigue crack initiation are related to compatibility of local deformation and microstructural changes during thermal fatigue process.

Recent Developments in the R5 Procedures for Assessing the High Temperature Response of Structures

2019 ◽  
Author(s):  
Daniel G. J. Hughes ◽  
Marc Chevalier ◽  
David W. Dean
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Crack Initiation ◽  
High Temperatures ◽  
Fatigue Crack Initiation ◽  
Term Operation ◽  
Creep Fatigue ◽  
Recent Developments ◽  
Creep Fatigue Crack ◽  
The Uk

Abstract The R5 procedures have been developed within the UK power generation industry to assess the integrity of nuclear and conventional plant operating at high temperatures. Within R5, there are specific procedures for assessing creep-fatigue crack initiation in initially defect-free components (Volume 2/3), components containing defects (Volume 4/5), dissimilar metal weldments (Volume 6) and similar metal ferritic weldments under steady loading (Volume 7). A key driver for continued developments in the R5 Procedure is the operational feedback from thirty years of operation of the UK Advanced Gas-Cooled Reactor (AGR) fleet. This experience from operation of the UK AGR fleet can be used to inform the design and operation of future high temperature reactors. Some of the lessons learnt from long-term operation of austenitic stainless steels at high temperatures are detailed briefly within this paper. Further, this paper briefly outlines the current R5 procedures and then focuses on two significant recent developments in these procedures: treatment of carburisation and its impact on creep-fatigue crack initiation and improved methods for predicting creep-fatigue crack growth under combined primary and secondary loads.

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