Development of a Fatigue Design Curve for Austenitic Stainless Steels in LWR Environments: A Review

2002 ◽  
Author(s):  
Omesh K. Chopra
Keyword(s):  
Stainless Steels ◽  
Pressure Vessel ◽  
Type Strain ◽  
Nuclear Power ◽  
Austenitic Stainless Steels ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Code Design ◽  
Fatigue Design ◽  
Asme Code

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components and 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 paper reviews the existing fatigue ε–N data for austenitic stainless steels in LWR coolant environments. The effects of key material, loading, and environmental parameters, such as steel type, strain amplitude, strain rate, temperature, dissolved oxygen level in water, and flow rate, on the fatigue lives of these steels are summarized. Statistical models are presented for estimating the fatigue ε–N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue design curves.

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.

The Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials

2006 ◽  
Author(s):  
Omesh K. Chopra ◽  
William J. Shack
Keyword(s):  
Stainless Steels ◽  
Type Strain ◽  
Water Flow Rate ◽  
Austenitic Stainless Steels ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Reactor Materials ◽  
American Society

The existing fatigue strain–vs.–life (ε–N) data illustrate potentially significant effects of light water reactor (LWR) coolant environments on the fatigue resistance of pressure vessel and piping steels. This paper reviews the existing fatigue ε–N data for carbon and low–alloy steels and austenitic stainless steels in LWR coolant environments. The effects of key material, loading, and environmental parameters, such as steel type, strain amplitude, strain rate, temperature, dissolved oxygen level in water, flow rate, surface finish, and heat-to-heat variation, on the fatigue lives of these steels are summarized. An updated version of the ANL statistical models is presented for estimating the fatigue ε–N curves for these steels as a function of the material, loading, and environmental parameters. The Fen (environmental fatigue correction factor) approach for incorporating the effects of LWR coolant environments into the fatigue evaluations of the American Society of Mechanical Engineers Code is presented.

Contributions of Dr. Sumio Yukawa in the Development of Non-Ductile Failure Prevention Rules in the ASME Code

2008 ◽  
Author(s):  
Hardayal S. Mehta
Keyword(s):  
Elevated Temperature ◽  
Carbon Steel ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Nickel Alloys ◽  
Ductile Failure ◽  
Austenitic Stainless Steels ◽  
Current Status ◽  
Asme Code

The objective of this paper is to review and highlight the contributions of Dr. Sumio Yukawa in the development of rules for the prevention of non-ductile failure in the ASME Boiler and Pressure Vessel Code. This includes review of his role in the development of WRC-175, Appendix G of Section III, the development of early flaw evaluation rules for carbon steel piping and in the review and evaluation of the toughness of austenitic stainless steels and nickel alloys after long-term elevated temperature exposures. The current status of these activities is briefly described.

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.

Selection of Metal Electrodes for and Effect of Welding Treatment on Hardness and Microstructure of Some Type of Austenitic Stainless Steels

2009 ◽  
Author(s):  
M. M. Ibrahim ◽  
H. G. Mohamed ◽  
Y. E. Tawfik
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Plate Thickness ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Aisi 304L ◽  
Stress Relieving ◽  
Selection Of

Austenitic stainless steels have been the focus of considerable research recently because of their high strength, good ductility, excellent corrosion resistance and a reasonable weldability. These properties make austenitic stainless steels attractive candidate materials for use in the fabrication of piping systems, automotive exhaust gas systems and in a variety of equipment associated with the chemical and nuclear power industries. PWHT is a stress relieving process whereby residual stresses are reduced by typically heating to 550–650 °C for a set time depending upon plate thickness. The effect of PWHT on mechanical properties such as hardness, ultimate tensile strength, yield strength, impact energy and ductile to brittle transition temperature are of great concern to the pressure vessel industry and pressure vessel codes. This paper reports on the effect of multiple PWHT on hardness and microstructure of austenitic stainless steels. The 6 mm AISI 304L, 316L, and 347 austenitic stainless steels were used for this work. This welds were produced by SMAW and GTAW techniques using a single vee preparation and multiple weld beads, and welded by various types of consumables. Selection of a suitable consumables metals for joining those weldment sample joints are an important criterion in view of the differences in physical, chemical, and mechanical properties of the base materials involved.

A Consideration of Margin on Fatigue Design Curves for Carbon and Low-Alloy Steels

2011 ◽  
Author(s):  
Makoto Higuchi ◽  
Masahiro Takanashi ◽  
Ichiro Tamura ◽  
Toshiaki Takada
Keyword(s):  
Stainless Steels ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Ferritic Steels ◽  
Low Alloy Steels ◽  
Light Water ◽  
Fatigue Design ◽  
The Us ◽  
Asme Code ◽  
Alloy Steels

In 2007, the US NRC issued Regulatory Guide 1.207[1] and NUREG/CR-6909[2] for evaluating fatigue incorporating the life reduction due to the effects of light-water reactor environment for new reactors. NUREG/CR-6909 provides new design fatigue curves (DFC) for carbon, low-alloy and stainless steels which are different from those in the ASME Boiler and Pressure Vessel Code Section III[3] (2007 Edition). The design fatigue curves for carbon and low-alloy steels in NUREG/CR-6909 are higher than that for ferritic steels of which specified minimum tensile strength is 552 MPa (80 ksi) or less in the ASME Code Section III. The design fatigue curve for stainless steel in the ASME Code Section III was changed to the same curve as NUREG/CR-6909 in the 2009 Addenda. However, those for carbon and low-alloy steels are still different from the NUREG curves.

A Review of the Effects of Coolant Environments on the Fatigue Life of LWR Structural Materials

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
O. K. Chopra ◽  
W. J. Shack
Keyword(s):  
Fatigue Life ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Fatigue Crack Initiation ◽  
Austenitic Stainless Steels ◽  
Structural Materials ◽  
Low Alloy Steels ◽  
Asme Code ◽  
Alloy Steels

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code specifies design curves for the fatigue life of structural materials in nuclear power plants. However, the effects of light water reactor (LWR) coolant environments were not explicitly considered in the development of the design curves. The existing fatigue-strain-versus-life (ε-N) data indicate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives in water relative to those in air can be a factor of 15 lower for austenitic stainless steels and a factor of ≈30 lower for carbon and low-alloy steels. This paper reviews the current technical basis for the understanding of the fatigue of piping and pressure vessel steels in LWR environments. The existing fatigue ε-N data have been evaluated to identify the various material, environmental, and loading parameters that influence fatigue crack initiation and to establish the effects of key parameters on the fatigue life of these steels. Statistical models are presented for estimating fatigue life as a function of material, loading, and environmental conditions. An environmental fatigue correction factor for incorporating the effects of LWR environments into ASME Code fatigue evaluations is described. This paper also presents a critical review of the ASME Code fatigue design margins of 2 on stress (or strain) and 20 on life and assesses the possible conservatism in the current choice of design margins.

Derivation of Design Fatigue Curves for Austenitic Stainless Steel Grades 1.4541 and 1.4550 Within the German Nuclear Safety Standard KTA 3201.2

2013 ◽  
Author(s):  
Xaver Schuler ◽  
Karl-Heinz Herter ◽  
Jürgen Rudolph
Keyword(s):  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Austenitic Stainless Steels ◽  
Nuclear Safety ◽  
Safety Standard ◽  
Fatigue Design ◽  
Steel Grades ◽  
Best Fit

Titanium and niobium stabilized austenitic stainless steels X6CrNiTi18-10S (material number 1.4541, correspondent to Alloy 321) respectively X6CrNiNb18-10S (material number 1.4550, correspondent to Alloy 347) are widely applied materials in German nuclear power plant components. Related requirements are defined in Nuclear Safety Standard KTA 3201.1. Fatigue design analysis is based on Nuclear Safety Standard KTA 3201.2. The fatigue design curve for austenitic stainless steels in the current valid edition of KTA 3201.2 is essentially identical with the design curve included in ASME-BPVC III, App I (ed. 2007, add. July 2008 respectively back editions). In the current code revision activities of KTA 3201.2 the compatibility of latest in air fatigue data for austenitic stainless steels with the above mentioned grades were examined in detail. The examinations were based on statistical evaluations of 149 strain controlled test data at room temperature and 129 data at elevated temperatures to derive best-fit mean data curves. Results of two additional load controlled test series (at room temperature and 288°C) in the high cycle regime were used to determine a technical endurance limit at 107 cycles. The related strain amplitudes were determined by consideration of the cyclic stress strain curve. The available fatigue data for the two austenitic materials at room temperature and elevated temperatures showed a clear temperature dependence in the high cycle regime demanding for two different best-fit curves. The correlation of the technical endurance limit(s) at room temperature and elevated temperatures with the ultimate strength of the materials is discussed. Design fatigue curves were derived by application of the well known factors to the best-fit curves. A factor of SN = 12 was applied to load cycles correspondent to the NUREG/CR-6909 approach covering influences of data scatter, surface roughness, size and sequence. In terms of strain respectively stress amplitudes in the high cycle regime, for elevated temperatures (>80°C) a factor of Sσ = 1.79 was applied considering and combining in detail the partial influences of data scatter surface roughness, size and mean stress. For room temperature a factor of Sσ = 1.88 shall be applied. As a result, new design fatigue curves for austenitic stainless steel grades 1.4541 and 1.4550 will be available within the German Nuclear Safety Standard KTA 3201.2. The fatigue design rules for all other austenitic stainless steel grades will be based on the new ASME-BPVC III, App I (ed. 2010) design curve.

Development of New Material Testing Apparatus in High-Pressure Hydrogen and Evaluation of Hydrogen Gas Embrittlement of Metals

2007 ◽  
Author(s):  
Seiji Fukuyama ◽  
Masaaki Imade ◽  
Kiyoshi Yokogawa
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Austenitic Stainless Steels ◽  
Material Testing ◽  
Hydrogen Gas ◽  
Stage Ii ◽  
Fuel Cell Vehicle ◽  
Stage Iii ◽  
Pressure Hydrogen

A new type of apparatus for material testing in high-pressure gas of up to 100 MPa was developed. The apparatus consists of a pressure vessel and a high-pressure control system that applies the controlled pressure to the pressure vessel. A piston is installed inside a cylinder in the pressure vessel, and a specimen is connected to the lower part of the piston. The load is caused by the pressure difference between the upper room and the lower room separated by the piston, which can be controlled to a loading mode by the pressure valves of the high-pressure system supplying gas to the vessel. Hydrogen gas embrittlement (HGE) and internal reversible hydrogen embrittlement (IRHE) of austenitic stainless steels and iron- and nickel-based superalloys used for high-pressure hydrogen storage of fuel cell vehicle were evaluated by conducting tensile tests in 70 MPa hydrogen. Although the HGE of these metals depended on modified Ni equivalent, the IRHE did not. The HGE of austenitic stainless steels was larger than their IRHE; however, the HGE of superalloys was not always larger than their IRHE. The effects of the chemical composition and metallic structure of these materials on the HGE and IRHE were discussed. The HGE of austenitic stainless steels was examined in 105 MPa hydrogen. The following were identified; SUS304: HGE in stage II, solution-annealed SUS316: HGE in stage III, sensitized SUS316: HGE in stage II, SUS316L: HGE in FS, SUS316LN: HGE in stage III and SUS310S: no HGE.

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