Effect of Maximum Temperature on the Thermal Fatigue Behavior of Superalloy GH536

2016 ◽  
Vol 853 ◽  
pp. 28-32 ◽  
Author(s):  
Jing Chen ◽  
Duo Qi Shi ◽  
Guo Lei Miao ◽  
Xiao Guang Yang
Keyword(s):  
Crack Initiation ◽  
Fatigue Test ◽  
Thermal Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Maximum Temperature ◽  
Thermal Fatigue Crack ◽  
Thermal Fatigue Test

Thermal fatigue tests of superalloy GH536 were carried out at different maximum temperature. Three-dimensional numerical finite element computations were performed to simulate thermal fatigue test process. The crack initiation, propagation and thermal fatigue failure mechanism of GH536 plate at different maximum temperatures were obtained by experiments and numerical methods. Result shows that the crack initiation life is shortened and the crack growth rate is accelerated with the increase of the maximum temperature of thermal fatigue test. The numbers of appearing 1 mm length cracks are 180, 74 and 37, respectively, when the maximum temperature is 800°C, 850°C and 900°C respectively. So the thermal fatigue performance decreases with the increase of the maximum temperature. But in the thermal fatigue tests of different maximum temperature, the thermal fatigue crack initiation is all caused by a single crack initiation source, and the thermal fatigue cracks initiate transgranularly, develop and propagate intergranularly.

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.

Fatigue Crack Initiation and Growth in Stainless Steel Pipe Welds

2009 ◽  
Author(s):  
D. Green ◽  
R. D. Smith ◽  
J. P. Taggart ◽  
D. Beardsmore ◽  
S. Robinson
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Thermal Loading ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Cyclic Hardening ◽  
Element Model ◽  
Fatigue Tests ◽  
Welded Pipe ◽  
Pipe Work

Thermal fatigue cracks have been found in austenitic pipe work in many pressurised water reactors, caused by thermal cycling due to the passage of water at different temperatures along the pipe inner surface. The rates of crack initiation and growth for this situation are not well understood because of the stochastic nature of the temperature fluctuations. Therefore, large allowances must be made when assessing the integrity of this pipe work to this failure mechanism. Improved assessment of crack initiation and growth could enable increased plant availability, and better safety cases. A programme of work has been completed consisting of fatigue tests on thick 304L butt-welded pipe specimens, and accompanying predictions of crack initiation and growth. In each test, uniform thermal cycles were generated using a water jet on a small area of the pipe. The magnitude of the cycles differed between the tests. Crack initiation and growth were monitored using a dye penetrant technique, applied to the pipe inner and outer surfaces, together with destructive examination. Crack initiation predictions were made using fatigue data derived from mechanical fatigue tests on the same material as in the pipe specimens. Good predictions were made using a strain-life endurance curve at a temperature corresponding to the average temperature of the metal surface during the thermal cycle. Crack growth predictions were based on an inelastic finite-element model accounting for cyclic hardening, and an enhanced R5 procedure (1) with crack closure taken into account. A linear elastic fracture mechanics definition of a Paris law for crack growth was used, and plastic redistribution effects were included. Predictions were good for all of the experimental scenarios carried out. A further experimental and analytical programme is in hand using the same experimental arrangements, concerning variable amplitude thermal loading.

Thermal Fatigue Crack Initiation and Related Microstructural Evolution in Sn/3.0Ag/0.5Cu Solder Joints

2002 ◽  
Vol 2002.6 (0) ◽  
pp. 279-280
Author(s):  
Toshihiko SAYAMA ◽  
Takao MORI ◽  
Satoko YAMAZAKI ◽  
Yoshiaki NAGAI ◽  
Takeshi TAKAYANAGI ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Microstructural Evolution ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Thermal Fatigue Crack

Thermal fatigue crack initiation and related microstructural evolution in Sn/3.5Ag eutectic solder joints

2002 ◽  
Vol 2002.6 (0) ◽  
pp. 277-278
Author(s):  
Toshihiko SAYAMA ◽  
Takao MORI ◽  
Takahiro OHNISHI ◽  
Yoshiaki NAGAI ◽  
Takeshi TAKAYANAGI ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Microstructural Evolution ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Eutectic Solder ◽  
Thermal Fatigue Crack

1108 Prediction Accuracy of Thermal Fatigue Crack Initiation in Sn-3.0Ag-0.5Cu Solder Joints

2008 ◽  
Vol 2008.6 (0) ◽  
pp. 221-222
Author(s):  
Yasuhiro EJIRI ◽  
Hiroyuki NAKANO ◽  
Takao MORI ◽  
Toshihiko SAYAMA ◽  
Takeshi TAKAYANAGI ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Thermal Fatigue ◽  
Prediction Accuracy ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Thermal Fatigue Crack

Thermal Fatigue Test on Dissimilar Welded Joint Between Gr.91 and 304SS

2017 ◽  
Author(s):  
Takashi Wakai ◽  
Sumio Kobayashi ◽  
Shoichi Kato ◽  
Masanori Ando ◽  
Hideki Takasho
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Thermal Fatigue ◽  
Evaluation Method ◽  
Welded Joint ◽  
Fatigue Cracks ◽  
Damage Evaluation ◽  
Thermal Fatigue Test ◽  
Dissimilar Welded Joint ◽  
Creep Fatigue

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of Japan sodium cooled fast reactor (JSFR), there may be dissimilar welded joints between ferritic and austenitic steels especially in intermediate heat exchangers (IHX) and steam generators (SG). Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and type 304 austenitic stainless steel (304SS) was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the heat affected zone (HAZ) in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in base metal (BM) of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.

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