Techniques for Fatigue Testing and Extrapolation of Fatigue Life for Austenitic Stainless Steels

1982 ◽  
Vol 10 (3) ◽  
pp. 115
Author(s):  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
M Bruce Vieth ◽  
MJ Manjoine ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stainless Steels ◽  
Fatigue Testing ◽  
Austenitic Stainless Steels

Influence of the Martensitic Transformation on the Fatigue Life of Austenitic Stainless Steels

2009 ◽  
Vol 423 ◽  
pp. 99-104
Author(s):  
Gemma Fargas ◽  
Marc Anglada ◽  
Antonio Mateo
Keyword(s):  
Fatigue Life ◽  
Martensitic Transformation ◽  
Stainless Steels ◽  
Stress Ratio ◽  
Fatigue Testing ◽  
High Stress ◽  
Austenitic Stainless Steels ◽  
Torsion Angles ◽  
Stress Ratios ◽  
Positive Effect

The martensitic transformation in austenitic stainless steels can be induced by plastic deformation at room temperature. The benefit of this transformation is commonly used to strengthen stainless steels grades, i.e. their yield and tensile resistance can be adjusted according to the requirement by cold rolling. In this paper, the martensitic transformation was induced by means of torsion deformation. Several torsion angles were selected to achieve different percentages of martensite at the surface of the specimens and then the effect on the fatigue life of the steel was studied. Fatigue testing results showed dissimilar behavior depending on the stress ratio (R) applied during the test. As a conclusion, the presence of martensite in the surface increases the fatigue life for high stress ratios (R=0.8), while at low R values martensitic transformation has no positive effect.

Proposal of Fatigue Life Equations for Carbon and Low-Alloy Steels and Austenitic Stainless Steels as a Function of Tensile Strength

2013 ◽  
Author(s):  
Hiroshi Kanasaki ◽  
Makoto Higuchi ◽  
Seiji Asada ◽  
Munehiro Yasuda ◽  
Takehiko Sera
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Low Alloy Steels ◽  
Strength Based ◽  
Fatigue Data ◽  
Current Design ◽  
Alloy Steels

Fatigue life equations for carbon & low-alloy steels and also austenitic stainless steels are proposed as a function of their tensile strength based on large number of fatigue data tested in air at RT to high temperature. The proposed equations give a very good estimation of fatigue life for the steels of varying tensile strength. These results indicate that the current design fatigue curves may be overly conservative at the tensile strength level of 550 MPa for carbon & low-alloy steels. As for austenitic stainless steels, the proposed fatigue life equation is applicable at room temperature to 430 °C and gives more accurate prediction compared to the previously proposed equation which is not function of temperature and tensile strength.

Explicit Quantification of the Interaction Between the PWR Environment and Component Surface Finish in Environmental Fatigue Evaluation Methods for Austenitic Stainless Steels

2018 ◽  
Author(s):  
Thomas Métais ◽  
Andrew Morley ◽  
Laurent de Baglion ◽  
David Tice ◽  
Gary L. Stevens ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Surface Finish ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Polished Surface ◽  
Small Scale ◽  
Draft Code ◽  
Design Curve ◽  
Wide Range

Additional fatigue rules within the ASME Boiler and Pressure Vessel Code have been developed over the past decade or so, such as those in Code Case N-792-1 [1], which provides an acceptable method to describe the effects of BWR and PWR environments on the fatigue life of components. The incorporation of environmental effects into fatigue calculations is performed via an environmental factor, Fen, and depends on factors such as the temperature, dissolved oxygen and strain rate. In the case of strain rate, lower strain rates (i.e., from slow transients) aggravate the Fen factor which counters the long-held notion that step (fast) transients cause the highest fatigue usage. A wide range of other factors, such as surface finish, can have a deleterious impact on fatigue life, but their impact on fatigue life is typically considered by including transition sub-factors to construct the fatigue design curve from the mean behavior air curve rather than in an explicit way, such as the Fen factor. An extensive amount of testing and evaluation has been conducted and reported in References [2] [3] [4] [5] [6] [7] and [8] that were used to both revise the transition factors and devise the Fen equations contained in Code Case N-792-1. The testing supporting the definition of Fen was performed on small-scale laboratory specimens with a polished surface finish on the basis that the Fen factor is applicable to the design curve without any impact on the transition factors. The work initiated by AREVA in 2005 [4] [5] [6] suggested, in testing of austenitic stainless steels, an interaction between the two aggravating effects of surface finish and PWR environment on fatigue damage. These results have been supported by testing carried out independently in the UK by Rolls-Royce and AMEC Foster Wheeler (now Wood Group) [7], also on austenitic stainless steels. The key finding from these investigations is that the combined detrimental effects of a PWR environment and a rough surface finish are substantially less than the sum of the two individual effects. These results are all the more relevant as most nuclear power plant (NPP) components do not have a polished surface finish. Most NPP component surfaces are either industrially ground or installed as-manufactured. The previous studies concluded that explicit consideration of the combined effects of environment and surface finish could potentially be applicable to a wide range of NPP components and would therefore be of interest to a wider community: EDF has therefore authored a draft Code Case introducing a factor, Fen-threshold, which explicitly quantifies the interaction between PWR environment and surface finish, as well as taking some credit for other conservatisms in the sub-factors that comprise the life transition sub-factor used to build the design fatigue curve . The contents of the draft Code Case were presented last year [9]. Since then, other international organizations have also made progress on these topics and developed their own views. The work performed is applicable to Austenitic Stainless Steels only for the time being. This paper aims therefore to present an update of the draft Code Case based on comments received to-date, and introduces some of the research and discussions which have been ongoing on this topic as part of an international EPRI collaborative group on environmental fatigue issues. It is intended to work towards an international consensus for a final version of the ASME Code Case for Fen-threshold.

EDF/NRC High-Cycle Fatigue Database Proposal

2015 ◽  
Author(s):  
T. P. Métais ◽  
G. Stevens ◽  
G. Blatman ◽  
J. C. Le Roux ◽  
R. L. Tregoning
Keyword(s):  
Stainless Steels ◽  
Data Exchange ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Austenitic Stainless Steels ◽  
Nuclear Regulatory Commission ◽  
Fatigue Curve ◽  
Research Data ◽  
Cycle Fatigue ◽  
Fatigue Data

Revised fatigue curves for austenitic stainless steels are currently being considered by several organizations in various countries, including Japan, South Korea, and France. The data available from laboratory tests indicate that the mean air curve considering all available austenitic material fatigue data may be overly conservative compared to a mean curve constructed from only those data representative of a particular type of material. In other words, developing separate fatigue curves for each of the different types of austenitic materials may prove useful in terms of removing excess conservatism in the estimation of fatigue lives. In practice, the fatigue curves of interest are documented in the various international design codes. For example, in the 2009 Addenda of Section III of the ASME Boiler and Pressure Vessel (BPV) Code [1], a revised design air fatigue curve for austenitic materials was implemented that was based on NRC research models [2]. More recently, in Japan, various industrial groups have joined their efforts to create the Design Fatigue Curve Sub-committee (DCFS) with the objective to reassess the fatigue curves [3]. In France, EDF/AREVA and CEA are developing a new fatigue curve for austenitic stainless steels [4]. More specifically, in 2014, EDF presented a paper on high-cycle fatigue analysis which demonstrated that the factor on the strain amplitude could be reduced from 2 to 1.4 for the RCC-M austenitic stainless steel grades [5]. Recently, discussions between EDF and the U.S. Nuclear Regulatory Commission (NRC) have led both parties to recognize that there is a need to exchange worldwide research data from fatigue testing to promote a common, vetted database available to all researchers. These discussions have led EDF and NRC to pursue a collaborative agreement and associated fatigue data exchange, with the intent to assemble all available fatigue data for austenitic materials into a standardized format. The longer term objective is to perform common analyses on the consolidated set of data. This paper summarizes the intent and of the preliminary results of this cooperation and also provides insights from both organizations on possible future activities and participation in the global exchange of fatigue research data.

scholarly journals Fatigue Life of Austenitic Stainless Steel in Hydrogen Environments

2015 ◽  
Author(s):  
Chris San Marchi ◽  
Jonathan A. Zimmerman ◽  
X. Tang ◽  
Samuel J. Kernion ◽  
Konrad Thürmer ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fuel Cell ◽  
Low Temperature ◽  
Stainless Steels ◽  
Nickel Content ◽  
Austenitic Stainless Steels ◽  
Fuel Cell Vehicle ◽  
High Yield ◽  
Service Temperature ◽  
Temperature Range

Gas-handling components for high-pressure gaseous hydrogen (such as in the fuel system of fuel cell electric vehicles) are manufactured almost exclusively from austenitic stainless steels. Relatively few studies, however, have evaluated the fatigue life of this class of steels in hydrogen environments, especially at low temperature. Low temperature is important for two reasons: (1) austenitic stainless steels show an apparent minimum in tensile ductility at temperature near 220K when exposed to hydrogen environments; and (2) the service temperature range for the automotive industry is generally consider to be 233K to 358K (−40°C to +85°C). While the temperature of maximum hydrogen embrittlement from tensile tests is very near the minimum of the service temperature range, it remains unclear if the same trend applies to fatigue life properties. In this paper, we evaluate the effect of hydrogen on fatigue life of strain-hardened Type 316L. The tested alloy features a relatively high nickel content of 12 wt% and high yield strength of 590 MPa. Additionally, reduction of cost and weight of hydrogen-handling components is necessary to enhance the competitiveness of fuel cell vehicle technologies. Cost reductions can be achieved by considering alloys with lower nickel content, while higher strength materials enable lower weight. Simple estimates of cost and weight reductions that can be realized are discussed.

scholarly journals Effect of the Addition of Nitrogen through Shielding Gas on TIG Welds Made Homogenously and Heterogeneously on 300 Series Austenitic Stainless Steels

2021 ◽  
Vol 5 (3) ◽  
pp. 72
Author(s):  
Rohit Kshirsagar ◽  
Steve Jones ◽  
Jonathan Lawrence ◽  
Jamil Kanfoud
Keyword(s):  
Fatigue Life ◽  
Stainless Steels ◽  
Feed Rate ◽  
Welding Process ◽  
Austenitic Stainless Steels ◽  
Interaction Effects ◽  
Bead Geometry ◽  
Filler Wire ◽  
Shielding Gas ◽  
Wire Feed

Tungsten inert gas (TIG) welding of austenitic stainless steels is a critical process used in industries. Several properties of the welds must be controlled depending on the application. These properties, which include the geometrical, mechanical and microstructural features, can be modified through an appropriate composition of shielding gas. Researchers have studied the effects of the addition of nitrogen through the shielding gas; however, due to limited amount of experimental data, many of the interaction effects are not yet reported. In this study, welds were made homogeneously as well as heterogeneously with various concentrations of nitrogen added through the shielding gas. The gas compositions used were 99.99%Ar (pure), 2.5% N2 + Ar, 5% N2 + Ar and 10% N2 + Ar. Additionally, the welding process parameters were varied to understand different interaction effects between the shielding gas chemistry and the process variables such as filler wire feed rate, welding current, etc. Strong interactions were observed in the case of heterogeneous welds between the gas composition and the filler wire feed rate, with the penetration depth increasing by nearly 30% with the addition of 10% nitrogen in the shielding gas. The interactions were found to influence the bead geometry, which, in turn, had an effect on the mechanical properties as well as the fatigue life of the welds. A nearly 15% increase in the tensile strength of the samples was observed when using 10% nitrogen in the shielding gas, which also translated to a similar increase in the fatigue life.

Evaluation of Hydrogen Environment Embrittlement and Fatigue Properties of Stainless Steels in High Pressure Gaseous Hydrogen: Investigation of Materials Properties in High Pressure Gaseous Hydrogen—2

2007 ◽  
Author(s):  
Tomohiko Omura ◽  
Mitsuo Miyahara ◽  
Hiroyuki Semba ◽  
Masaaki Igarashi ◽  
Hiroyuki Hirata
Keyword(s):  
High Pressure ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Gaseous Hydrogen ◽  
Fatigue Properties ◽  
Chemical Compositions ◽  
Hydrogen Environment

Hydrogen environment embrittlement (HEE) susceptibility in high pressure gaseous hydrogen was investigated on 300 series austenitic stainless steels and A6061-T6 aluminum alloy. Tensile properties of these materials were evaluated by Slow Strain Rate Testing (SSRT) in gaseous hydrogen pressurized up to 90MPa (13053 psig) in the temperature range from −40 to 85 degrees C (−40 to 185 degrees F). HEE susceptibilities of austenitic stainless steels strongly depended upon the chemical compositions and testing temperatures. A6061-T6 aluminum alloy showed no degradation by hydrogen. Fatigue properties in high pressure gaseous hydrogen were evaluated by the external cyclic pressurization test using tubular specimens. The tubular specimen was filled with high pressure hydrogen gas, and the outside of the specimen was cyclically pressurized with water. Type 304 showed a decrease in the fatigue life in hydrogen gas, while as for type 316L and A6061-T6 the difference of the fatigue life between hydrogen and argon environments was small. HEE susceptibility of investigated materials was discussed based on the stability of an austenitic structure.

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