scholarly journals Planned FY19 creep and fatigue design curve testing of Alloy 709 base metal

2019 ◽  
Author(s):  
Yanli Wang ◽  
Sam Sham
Keyword(s):  
Base Metal ◽  
Design Curve ◽  
Fatigue Design

scholarly journals Fatigue Design Curves for 6061-T6 Aluminum

1997 ◽  
Vol 119 (2) ◽  
pp. 211-215 ◽  
Author(s):  
G. T. Yahr
Keyword(s):  
Base Metal ◽  
Neutron Source ◽  
Pressure Vessel ◽  
Research Reactor ◽  
Mean Stress ◽  
Design Curve ◽  
Stress Effects ◽  
Fatigue Design ◽  
Fatigue Data ◽  
Class 1

A request has been made to the ASME Boiler and Pressure Vessel Committee that 6061-T6 aluminum be approved for use in the construction of Class 1 welded nuclear vessels so it can be used for the pressure vessel of the Advanced Neutron Source research reactor. Fatigue design curves with and without mean stress effects have been proposed. A knock-down factor of 2 is applied to the design curve for evaluation of welds. The basis of the curves is explained. The fatigue design curves are compared to fatigue data from base metal and weldments.

ASME Code-Case Proposal to Explicitly Quantify the Interaction Between the PWR Environment and Component Surface Finish

2017 ◽  
Author(s):  
Thomas Métais ◽  
Stéphan Courtin ◽  
Laurent De Baglion ◽  
Cédric Gourdin ◽  
Jean-Christophe Le Roux
Keyword(s):  
Fatigue Life ◽  
Surface Finish ◽  
Polished Surface ◽  
Design Curve ◽  
Fatigue Design ◽  
Wide Range ◽  
Asme Code ◽  
The Difference ◽  
The Uk ◽  
Technical Basis

Fatigue rules from ASME have undergone a significant change over the past decade, especially with the inclusion of the effects of BWR and PWR environments on the fatigue life of components. The incorporation of the environmental effects into the calculations is performed via an environmental factor, Fen, which is introduced in ASME BPV code-case N-792 [5], and depends on factors such as the temperature, dissolved oxygen and strain rate. Nevertheless, a wide range of factors, such as surface finish, have a deleterious impact on fatigue life, but their contribution to fatigue life is typically taken through the transition factors to build the fatigue design curve [2] and not in an explicit way, such as the Fen factor. The testing supporting the rules pertaining to Environmental Fatigue Correction Factor (Fen) Method in ASME BPV was performed on specimens with a polished surface finish and on the basis that the Fen factor was applicable without alteration of the historical practice of building the design curve through transition factors. The extensive amount of testing conducted and reported in References [2] and [7] (technical basis for ASME BPV current EAF rules) was used to propose a set of transition coefficients from the mean air curve to the design curve on one hand, and on the other hand to build a Fen factor expression, defined as the difference between the life in air and in PWR environments. The work initiated by AREVA in 2005 [9] [10] [11] demonstrated that there is a clear interaction between the two aggravating effects of surface finish and PWR environment for fatigue damage, which was not experimentally tested in the References [2] and [7]. These results have clearly been supported by testing carried out independently in the UK by Rolls-Royce and AMEC FW [12]. These results are all the more relevant as most NPP components do not have a polished surface finish. Most surfaces are either industrially polished or installed as-manufactured. It was concluded that this proposal could potentially be applicable to a wide range of components and could be of interest to a wider community. EDF/Areva/CEA have therefore authored a code-case introducing the Fen-threshold, a factor which explicitly quantifies the interaction between PWR environment and surface finish. This paper summarizes this proposal and provides the technical background and experimental work to justify this proposal.

scholarly journals Development of a Water Environment Fatigue Design Curve for Austenitic Stainless Steels

2003 ◽  
Author(s):  
Thomas R. Leax
Keyword(s):  
Stainless Steels ◽  
Fatigue Behavior ◽  
Water Environment ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Design Curve ◽  
Fatigue Design ◽  
American Society ◽  
Design Factors

Technical support is provided for a fatigue curve that could potentially be incorporated into Section III of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. This fatigue curve conservatively accounts for the effects of light water reactor environments on the fatigue behavior of austenitic stainless steels. This paper presents the data, statistical methods, and basis for the design factors appropriate for Code applications. A discussion of the assumptions and methods used in design curve development is presented.

Margins for ASME Code Fatigue Design Curve: Effects of Surface Finish and Material Variability

2003 ◽  
Author(s):  
O. K. Chopra ◽  
W. J. Shack
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Code Design ◽  
Low Alloy Steels ◽  
Design Curve ◽  
Fatigue Design ◽  
Asme Code ◽  
Alloy Steels

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. This Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life (ε-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue ε-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue ε-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for the ASME Code fatigue design curve is presented.

Analysis of Fatigue Crack Growth in Standard Endurance Test Specimens in Support of Total Life Approaches to Fatigue Assessment

2016 ◽  
Author(s):  
Jonathan Mann ◽  
Marius Twite ◽  
M. Grace Burke
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Austenitic Stainless Steel ◽  
Crack Growth ◽  
Load Drop ◽  
Design Curve ◽  
Fatigue Design ◽  
Numerical Predictions ◽  
Total Life ◽  
Plant Components

The ASME Boiler & Pressure Vessel Code Section III method for the evaluation of fatigue in nuclear plant components uses a fatigue design curve derived from the testing of standard cylindrical specimens to describe the fatigue endurance of austenitic stainless steel components. The test results describe the number of cycles to achieve a 25% total load drop within a standard specimen (approximately equal to a 3 mm crack) under membrane loading conditions and the design curve is commonly associated with fatigue initiation. However, for non-standard loading conditions, such as the case of a thermal gradient within a component where a crack may be growing into a decreasing stress field, this description of initiation may be overly conservative. Alternative approaches, such as the total life approach, may provide better representations of fatigue life in real plant components. By separating out quantifiable portions of long crack growth (Stage II) from the current design curve, alternative definitions of initiation can be derived and subsequently used in conjunction with standard fracture mechanics in order to model fatigue more accurately. In this paper numerical methods are used to model the fatigue crack growth between starting crack depths of 0.25 mm, and the depth associated with a 25% load drop in a standard cylindrical specimen. The numerical predictions are compared with striation spacings measured at a range of crack depths on the fracture surfaces of austenitic stainless steel specimens tested in both air and water environments, under strain control. A good correlation between numerical predictions and the measured striation spacings was obtained and the results are used to characterise different stages of fatigue cracking. Based upon the methods developed in this paper, modified fatigue design curves, using alternative definitions of crack initiation, are proposed and their applications in total life approaches to fatigue assessment are discussed, based on a worked example of a thermally fatigued stepped pipe experiment.

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