scholarly journals Report on FY 2020 creep, fatigue and creep fatigue testing of Alloy 709 base metal at ORNL

2020 ◽  
Author(s):  
Yanli Wang ◽  
Peijun Hou ◽  
Sam Sham
Keyword(s):  
Base Metal ◽  
Fatigue Testing ◽  
Creep Fatigue

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.

scholarly journals Microstructure evolution of alloy 709 during static-aging and creep-fatigue testing

2021 ◽  
Vol 801 ◽  
pp. 140361
Author(s):  
T.D. Porter ◽  
Z. Wang ◽  
E.P. Gilbert ◽  
M.J. Kaufman ◽  
R.N. Wright ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Fatigue Testing ◽  
Creep Fatigue

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.

Damage Assessment of Similar Martensitic Welds Under Creep, Fatigue and Creep-Fatigue Loading

2020 ◽  
Author(s):  
Thorben Bender ◽  
Andreas Klenk ◽  
Stefan Weihe
Keyword(s):  
Base Metal ◽  
Fatigue Behavior ◽  
Base Material ◽  
Fatigue Loading ◽  
Design Guidelines ◽  
Failure Behavior ◽  
Martensitic Steels ◽  
Viscoplastic Material ◽  
Local Strains ◽  
Creep Fatigue

Abstract For the assessment of welds under high-temperature conditions in the creep or creep-fatigue regimes, the knowledge on the damage location and its temporal evolution are of high importance. The failure behavior of similar welds of ferritic-martensitic steels in the creep regime is well known. For creep-fatigue loading, the behavior of welds is still subject to research but it seems that the heat affected zone (HAZ) limits the lifetime of welded components as well. This local failure behavior is not reflected in design guidelines using weld reduction factors or in typical assessment approaches. The evaluation of local strains and stresses in the HAZ is unavoidable. For the improvement of design and inspection guidelines, a more detailed consideration of weld behavior is of interest. In this paper, an overview of current developments in the assessment of welds under creep, fatigue, and creep-fatigue loading conditions is given. An assessment approach for creep damage and failure, including the prediction of rupture time and location, is presented. The assessment is based on numerical analyses considering the different behavior of base material and HAZ represented by three different subzones. The approach is validated with the simulation of a uniaxial cross weld, creep crack, and component tests. Whereas the creep behavior of the HAZ compared to base metal is quite well known, there is only little knowledge of their fatigue behavior. Using a set of fatigue tests on HAZ, base metal specimens and cross weld specimens, the influence of fatigue and creep-fatigue loading on the lifetime and failure location of a weld will be discussed. For the numerical simulations, a viscoplastic material law of Chaboche type is used and an evaluation of the local strains in the HAZ allows an attempt to explain the observed failure locations.

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