scholarly journals The Role of Environment on High Temperature Creep-Fatigue Behavior of Alloy 617

2010 ◽  
Author(s):  
Laura Carroll ◽  
Celine Cabet ◽  
Richard Wright
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Dominant Role ◽  
Hold Time ◽  
Outlet Temperature ◽  
Alloy 617 ◽  
Creep Fatigue

Alloy 617 is the leading candidate material for an intermediate heat exchanger (IHX) application of the Very High Temperature Nuclear Reactor (VHTR), expected to have an outlet temperature as high as 950°C. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior. Initial creep-fatigue work on Alloy 617 suggests a more dominant role of environment with increasing temperature and/or hold times evidenced through changes in creep-fatigue crack growth mechanism/s and failure life. Furthermore, previous work on corrosion of nickel base alloys in impure helium has suggested that this environment is far from inert with respect to Alloy 617. Continuous cycle fatigue and creep-fatigue testing of Alloy 617 was conducted at 950°C and 0.3% and 0.6% total strain in air to simulate damage modes expected in a VHTR application. Continuous cycle and creep-fatigue specimens exhibited intergranular cracking, but did not show evidence of grain boundary cavitation. Despite the absence of grain boundary cavitation to accelerate crack propagation, the addition of a hold time at peak tensile strain was detrimental to cycle life. This suggests that creep-fatigue interaction may occur by a different mechanism or that the environment may be partially responsible for accelerating failure.

Low Cycle Fatigue and Creep-Fatigue Behavior of Alloy 617 at High Temperature

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Celine Cabet ◽  
Laura Carroll ◽  
Richard Wright
Keyword(s):  
High Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Dominant Role ◽  
Hold Time ◽  
Outlet Temperature ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Creep Fatigue

Alloy 617 is the leading candidate material for an intermediate heat exchanger (IHX) application of the very high temperature nuclear reactor (VHTR), expected to have an outlet temperature as high as 950 °C. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior. Initial creep-fatigue work on Alloy 617 suggests a more dominant role of environment with increasing temperature and/or hold times evidenced through changes in creep-fatigue crack growth mechanisms and failure life. Continuous cycle fatigue and creep-fatigue testing of Alloy 617 was conducted at 950 °C and 0.3% and 0.6% total strain in air to simulate damage modes expected in a VHTR application. Continuous cycle fatigue specimens exhibited transgranular cracking. Intergranular cracking was observed in the creep-fatigue specimens and the addition of a hold time at peak tensile strain degraded the cycle life. This suggests that creep-fatigue interaction occurs and that the environment may be partially responsible for accelerating failure.

Role of grain boundary engineered microstructure on high temperature steam oxidation behaviour of Ni based superalloy alloy 617

2019 ◽  
Vol 778 ◽  
pp. 224-233 ◽  
Author(s):  
C.N. Athreya ◽  
K. Deepak ◽  
Dong-Ik Kim ◽  
B. de Boer ◽  
Sumantra Mandal ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Oxidation Behaviour ◽  
Steam Oxidation ◽  
Alloy 617 ◽  
High Temperature Steam

scholarly journals Determination of the Creep-Fatigue Interaction Diagram for Alloy 617

2016 ◽  
Author(s):  
J. K. Wright ◽  
L. J. Carroll ◽  
T.-L. Sham ◽  
N. J. Lybeck ◽  
R. N. Wright
Keyword(s):  
Fatigue Testing ◽  
Hold Time ◽  
Strain Range ◽  
Fatigue Tests ◽  
Alloy 617 ◽  
Interaction Diagram ◽  
Creep Fatigue ◽  
Intermediate Heat Exchanger ◽  
Cycles To Failure

Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor (VHTR). As part of evaluating the behavior of this material in the expected service conditions, creep–fatigue testing was performed. The cycles to failure decreased compared to fatigue values when a hold time was added at peak tensile strain. At 850°C, increasing the tensile hold duration continued to degrade the creep–fatigue resistance, at least to the investigated strain–controlled hold time of up to 60 minutes at the 0.3% strain range and 240 minutes at the 1.0% strain range. At 950°C, the creep–fatigue cycles to failure are not further reduced with increasing hold duration, indicating saturation occurs at relatively short hold times. The creep and fatigue damage fractions have been calculated and plotted on a creep–fatigue interaction D–diagram. Test data from creep–fatigue tests at 800 and 1000°C on an additional heat of Alloy 617 are also plotted on the D–diagram.

scholarly journals High-Temperature Creep-Fatigue Behavior of Alloy 617

Metals ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 103 ◽  
Author(s):  
Rando Dewa ◽  
Jeong Park ◽  
Seon Kim ◽  
Sang Lee
Keyword(s):  
High Temperature ◽  
Fatigue Behavior ◽  
High Temperature Creep ◽  
Alloy 617 ◽  
Temperature Creep ◽  
Creep Fatigue

Creep and Environmental Effects on the High Temperature Creep-Fatigue Behavior of Alloy 617

2011 ◽  
Vol 8 (6) ◽  
pp. 103797 ◽  
Author(s):  
L. J. Carroll ◽  
C. Cabet ◽  
R. Madland ◽  
R. N. Wright ◽  
A. Saxena ◽  
...  
Keyword(s):  
High Temperature ◽  
Environmental Effects ◽  
Fatigue Behavior ◽  
High Temperature Creep ◽  
Alloy 617 ◽  
Temperature Creep ◽  
Creep Fatigue

Creep-Fatigue Behavior in Ferritic-Martensitic Steels

2011 ◽  
Author(s):  
Meimei Li ◽  
Saurin Majumdar ◽  
Ken Natesan
Keyword(s):  
High Temperature ◽  
Stress Relaxation ◽  
Fatigue Behavior ◽  
Hold Time ◽  
Creep Damage ◽  
Cyclic Softening ◽  
Relaxation Response ◽  
Martensitic Steels ◽  
Softening Effect ◽  
Creep Fatigue

Ferritic-martensitic steels are the lead structural materials for next-generation nuclear energy systems. Due to increased operating temperatures required in advanced high-temperature reactor concepts, the high temperature performance of structural alloys and reliable high temperature structural design methodology have become increasingly urgent issues. Ferritic-martensitic steels experience significant cyclic softening at high temperatures, and this cyclic softening behavior affects consecutive stress relaxation response during hold time under creep-fatigue loading. It is found that the stress relaxation response during hold of the mod.9Cr-1Mo steel can be accurately described by a stress relaxation model. The creep damage associated with the stress relaxation during hold time can then be accurately calculated using the stress relaxation data and creep rupture data. It is shown that the unit creep damage per cycle in mod.9Cr-1Mo steel decreases considerably with increasing number of cycles due to cyclic softening, and the creep damage is sensitive to the initial stress of stress relaxation. Proper evaluation of the creep-fatigue damage in mod.9Cr-1Mo steel must consider the cyclic softening effect and its associated variations in creep damage from stress relaxation during the hold time.

High-Temperature Creep-Fatigue of Alloy 617 Base Metal and Weldments

2007 ◽  
Author(s):  
Terry C. Totemeier
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Fatigue Testing ◽  
Hold Time ◽  
Fatigue Cracking ◽  
Rolled Plate ◽  
Alloy 617 ◽  
Hold Period ◽  
Creep Fatigue ◽  
Metal Creep

Creep-fatigue testing of nickel alloy 617 base metal and fusion weldments was performed at temperatures of 800 and 1000°C in air in support of ASME BPV Sec III code qualification of alloy 617 for the Next-Generation Nuclear Plant. Cyclic loading was performed in strain control with a trapezoidal waveform and was fully reversed. Creep was introduced into the fatigue cycle by a hold period at maximum tensile strain which varied from 18 to 9000 seconds. Base metal specimens were machined from 20 mm thick rolled plate; weldment specimens were machined from GTAW butt-welded plate such that the loading direction was oriented transverse to the welding direction. Weld metal, heat-affected zone, and base metal were present in the reduced section of weldment specimens. Creep-fatigue lives decreased with increasing hold time for both base metal and weldments; lives of weldments were reduced relative to those of base metal. Creep-fatigue cracking in weldment specimens initiated in the weld metal.

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