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Sample records for vessel steel fatigue

  1. Corrosion fatigue of pressure vessel steels in PWR environments--influence of steel sulfur content

    International Nuclear Information System (INIS)

    Scott, P.M.; Druce, S.G.; Truswell, A.E.

    1984-01-01

    Large effects of simulated light water reactor environments at 288 C on fatigue crack growth in low alloy pressure vessel steels are observed only when specific mechanical, metallurgical, and electrochemical conditions are satisfied simultaneously. In this paper, the relative importance of three key variables--steel impurity content, water chemistry, and flow rate--and their interaction with loading rate or strain rate are examined. In particular, the results of a systematic examination of the influence of a steel's sulfur content are described

  2. Corrosion fatigue of pressure vessel steels in PWR environments--influence of steel sulfur content

    Energy Technology Data Exchange (ETDEWEB)

    Scott, P.M.; Druce, S.G.; Truswell, A.E.

    1984-07-01

    Large effects of simulated light water reactor environments at 288 C on fatigue crack growth in low alloy pressure vessel steels are observed only when specific mechanical, metallurgical, and electrochemical conditions are satisfied simultaneously. In this paper, the relative importance of three key variables--steel impurity content, water chemistry, and flow rate--and their interaction with loading rate or strain rate are examined. In particular, the results of a systematic examination of the influence of a steel's sulfur content are described.

  3. Fatigue crack propagation in neutron-irradiated ferritic pressure-vessel steels

    International Nuclear Information System (INIS)

    James, L.A.

    1977-01-01

    The results of a number of experiments dealing with fatigue crack propagation in irradiated reactor pressure-vessel steels are reviewed. The steels included ASTM alloys A302B, A533B, A508-2, and A543, as well as weldments in A543 steel. Fluences and irradiation conditions were generally typical of those experienced by most power reactors. In general, the effect of neutron irradiation on the fatigue crack propagation behavior of these steels was neither significantly beneficial nor significantly detrimental

  4. Isothermal and thermal–mechanical fatigue of VVER-440 reactor pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Fekete, Balazs, E-mail: fekete.mm.bme@gmail.com [College of Dunaujvaros, Tancsics 1A, Dunaujvaros H-2400 (Hungary); Department of Applied Mechanics, Budapest University of Technology and Economics, Muegyetem 5, Budapest H-1111 (Hungary); Trampus, Peter [College of Dunaujvaros, Tancsics 1A, Dunaujvaros H-2400 (Hungary)

    2015-09-15

    Highlights: • We aimed to determine the thermomechanical behaviour of VVER reactor steels. • Material tests were developed and performed on GLEEBLE 3800 physical simulator. • Coffin–Manson curves and parameters were derived. • High accuracy of the strain energy based evaluation was found. • The observed dislocation evolution correlates with the mechanical behaviour. - Abstract: The fatigue life of the structural materials 15Ch2MFA (CrMoV-alloyed ferritic steel) and 08Ch18N10T (CrNi-alloyed austenitic steel) of VVER-440 reactor pressure vessel under completely reserved total strain controlled low cycle fatigue tests were investigated. An advanced test facility was developed for GLEEBLE-3800 physical simulator which was able to perform thermomechanical fatigue experiments under in-service conditions of VVER nuclear reactors. The low cycle fatigue results were evaluated with the plastic strain based Coffin–Manson law, and plastic strain energy based model as well. It was shown that both methods are able to predict the fatigue life of reactor pressure vessel steels accurately. Interrupted fatigue tests were also carried out to investigate the kinetic of the fatigue evolution of the materials. On these samples microstructural evaluation by TEM was performed. The investigated low cycle fatigue behavior can provide reference for remaining life assessment and lifetime extension analysis.

  5. Isothermal and thermal-mechanical fatigue of VVER-440 reactor pressure vessel steels

    Science.gov (United States)

    Fekete, Balazs; Trampus, Peter

    2015-09-01

    The fatigue life of the structural materials 15Ch2MFA (CrMoV-alloyed ferritic steel) and 08Ch18N10T (CrNi-alloyed austenitic steel) of VVER-440 reactor pressure vessel under completely reserved total strain controlled low cycle fatigue tests were investigated. An advanced test facility was developed for GLEEBLE-3800 physical simulator which was able to perform thermomechanical fatigue experiments under in-service conditions of VVER nuclear reactors. The low cycle fatigue results were evaluated with the plastic strain based Coffin-Manson law, and plastic strain energy based model as well. It was shown that both methods are able to predict the fatigue life of reactor pressure vessel steels accurately. Interrupted fatigue tests were also carried out to investigate the kinetic of the fatigue evolution of the materials. On these samples microstructural evaluation by TEM was performed. The investigated low cycle fatigue behavior can provide reference for remaining life assessment and lifetime extension analysis.

  6. Gigacycle fatigue behaviour of austenitic stainless steels used for mercury target vessels

    International Nuclear Information System (INIS)

    Naoe, Takashi; Xiong, Zhihong; Futakawa, Masatoshi

    2016-01-01

    A mercury enclosure vessel for the pulsed spallation neutron source manufactured from a type 316L austenitic stainless steel, a so-called target vessel, suffers the cyclic loading caused by the proton beam induced pressure waves. A design criteria of the JSNS target vessel which is defined based on the irradiation damage is 2500 h at 1 MW with a repetition rate of 25 Hz, that is, the target vessel suffers approximately 10 9 cyclic loading while in operation. Furthermore, strain rate of the beam window of the target vessel reaches 50 s −1 at the maximum, which is much higher than that of the conventional fatigue. Gigacycle fatigue strength up to 10 9 cycles for solution annealed 316L (SA) and cold-worked 316L (CW) were investigated through the ultrasonic fatigue tests. Fatigue tests were performed under room temperature and 250 °C which is the maximum temperature evaluated at the beam window in order to investigate the effect of temperature on fatigue strength of SA and CW 316L. The results showed that the fatigue strength at 250 °C is clearly reduced in comparison with room temperature, regardless of cold work level. In addition, residual strength and microhardness of the fatigue tested specimen were measured to investigate the change in mechanical properties by cyclic loading. Cyclic hardening was observed in both the SA and CW 316L, and cyclic softening was observed in the initial stage of cyclic loading in CW 316L. Furthermore, abrupt temperature rising just before fatigue failure was observed regardless of testing conditions.

  7. On the transition of short cracks into long fatigue cracks in reactor pressure vessel steels

    Directory of Open Access Journals (Sweden)

    Singh Rajwinder

    2018-01-01

    Full Text Available Short fatigue cracks, having dimension less than 1 mm, propagate at much faster rates (da/dN even at lower stress intensity factor range (da/dN as compared to the threshold stress intensity factor range obtained from long fatigue crack growth studies. These short cracks originate at the sub-grain level and some of them ultimately transit into critical long cracks over time. Therefore, designing the components subjected to fatigue loading merely on the long crack growth data and neglecting the short crack growth behavior can overestimate the component’s life. This aspect of short fatigue cracks become even more critical for materials used for safety critical applications such as reactor pressure vessel (RPV steel in nuclear plants. In this work, the transition behaviour of short fatigue crack gowth into long fatigue crack is studied in SA508 Grade 3 Class I low alloy steel used in RPVs. In-situ characterization of initiation, propagation and transition of short fatigue cracks is performed using fatigue stage for Scanning Electron Microscope (SEM in addition to digital microscopes fitted over a servo-hydraulic fatigue machine and correlated with the microtructural information obtained using electron backscatter diffraction (EBSD. SA508 steel having an upper bainitic microstructure have several microstructural interfaces such as phase and grain boundaries that play a significant role in controlling the short fatigue crack propagation. Specially designed and prepared short fatigue specimens (eletro-polished with varying initial crack lengths of the order of tens of microns are used in this study. The transition of such short initial cracks into long cracks is then tracked to give detailed insight into the role of each phase and phase/grain boundary with an objective of establishing Kitagawa-Takahashi diagram for the given RPV steel. The behavior of the transited long cracks is then compared with the crack propagation behavior obtained using

  8. Effects of temperature on corrosion fatigue crack growth of pressure vessel steels in PWR coolant

    International Nuclear Information System (INIS)

    Tice, D.R.; Bramwell, I.L.; Fairbrother, H.; Worswick, D.

    1994-01-01

    This paper presents experimental results concerning crack propagation rates in A508-III pressure vessel steel (medium sulphur content) exposed to PWR primary water at temperatures between 130 and 290 C. The results indicate that the greatest increase in corrosion fatigue crack growth rate occurs at temperatures in the range 150 to 200 C. Under these conditions, there was a marked change in the appearance of the fracture surface, with extensive micro-branching of the crack front and occasional bifurcation of the whole crack path. In contrast, at 290 C, the fracture surface is smoother, similar to that due to inert fatigue. The implication of these observations for assessment of the pressure vessel integrity, is examined. 14 refs., 15 figs., 3 tabs

  9. Fatigue of non-welded pressure vessels made of high strength steel

    International Nuclear Information System (INIS)

    Rauscher, F.

    2003-01-01

    When using high strength steels for pressure vessels, cyclic fatigue requirements may become decisive for the design. Within a European research project, two typical non-welded types of vessels--gas cylinders as used for gas transportation and hydraulic accumulators with screwed in ends--were investigated. The results of the fatigue analyses and of the testing of these vessels are described here. Special attention is drawn to the evaluation of the stresses in the threads used for threaded in flat ends and rings, because the usual formulae for bolted connections cannot be used. In the case of sharp notches and of threads, the experiments showed that the fatigue calculation gave conservative results. The unexpected failure of the gas cylinders in the cylindrical part and at the onset of the end showed that the fatigue analyses according to prEN13445-3 clause 18 is non-conservative for these surfaces without mechanical preparation, and need special consideration. Based on the investigations, a stress concentration factor for small fabrication notches and a new surface finish factor is proposed

  10. Fatigue of non-welded pressure vessels made of high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Rauscher, F

    2003-03-01

    When using high strength steels for pressure vessels, cyclic fatigue requirements may become decisive for the design. Within a European research project, two typical non-welded types of vessels--gas cylinders as used for gas transportation and hydraulic accumulators with screwed in ends--were investigated. The results of the fatigue analyses and of the testing of these vessels are described here. Special attention is drawn to the evaluation of the stresses in the threads used for threaded in flat ends and rings, because the usual formulae for bolted connections cannot be used. In the case of sharp notches and of threads, the experiments showed that the fatigue calculation gave conservative results. The unexpected failure of the gas cylinders in the cylindrical part and at the onset of the end showed that the fatigue analyses according to prEN13445-3 clause 18 is non-conservative for these surfaces without mechanical preparation, and need special consideration. Based on the investigations, a stress concentration factor for small fabrication notches and a new surface finish factor is proposed.

  11. Influence of steel-making process and heat-treatment temperature on the fatigue and fracture properties of pressure vessel steels

    International Nuclear Information System (INIS)

    Koh, S. K.; Na, E. G.; Baek, T. H.; Won, S. Y.; Park, S. J.; Lee, S. W.

    2001-01-01

    In this paper, high strength pressure vessel steels having the same chemical compositions were manufactured by the two different steel-making processes, such as Vacuum Degassing(VD) and Electro-Slag Remelting(ESR) methods. After the steel-making process, they were normalized at 955 deg. C, quenched at 843 .deg. C, and finally tempered at 550 .deg. C or 450 deg. C, resulting in tempered martensitic microstructures with different yielding strengths depending on the tempering conditions. Low-Cycle Fatigue(LCF) tests, Fatigue Crack Growth Rate(FCGR) tests, and fracture toughness tests were performed to investigate the fatigue and fracture behaviors of the pressure vessel steels. In contrast to very similar monotonic, LCF, and FCGR behaviors between VD and ESR steels, a quite difference was noticed in the fracture toughness. Fracture toughness of ESR steel was higher than that of VD steel, being attributed to the removal of impurities in steel-making process

  12. Low cycle fatigue behavior of a ferritic reactor pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Apu, E-mail: asarkar@barc.gov.in; Kumawat, Bhupendra K.; Chakravartty, J.K.

    2015-07-15

    The cyclic stress–strain response and the low cycle fatigue (LCF) behavior of 20MnMoNi55 pressure vessel steel were studied. Tensile strength and LCF properties were examined at room temperature (RT) using specimens cut from rolling direction of a rolled block. The fully reversed strain-controlled LCF tests were conducted at a constant total strain rate with different axial strain amplitude levels. The cyclic strain–stress relationships and the strain–life relationships were obtained through the test results, and related LCF parameters of the steel were calculated. The studied steel exhibits cyclic softening behavior. Furthermore, analysis of stabilized hysteresis loops showed that the steel exhibits non-Masing behavior. Complementary scanning electron microscopy examinations were also carried out on fracture surfaces to reveal dominant damage mechanisms during crack initiation, propagation and fracture. Multiple crack initiation sites were observed on the fracture surface. The investigated LCF behavior can provide reference for pressure vessel life assessment and fracture mechanisms analysis.

  13. Development of a crack monitoring technique for use in a corrosion fatigue study of SA533-B pressure vessel steel

    International Nuclear Information System (INIS)

    Benson, J.M.; Tait, R.B.; Garrett, G.G.

    1981-10-01

    At present there does not exist a realistic crack growth law which will provide a good description of the relationship between the alternating stress intensity factor and the crack growth per cycle of stress. Such a law should be applicable to either the pressurized water reactor environment (PWR) or boiling water reactor environmnt (BWR). This project was formulated with the aim of examining the fatigue crack growth rate of SA533-B steel (a nuclear pressure vessel steel) in the threshold region in a simulated PWR environment. The aim of this report is to develop a crack monitoring technique for use in corrosion fatigue studies. Factors affecting fatigue crack propagation include: frequency, stress range, the effect of irradiation, ageing and environment. The mechanisms of crack propagation that are discussed include: slip dissolution, hydrogen assisted cracking, corrosion potential, and morphology studies. D.C. electrical potential, the compliance technique and the back-faced strain gauge method can be used for crack monitoring. Details are also given on the experimental equipment and programme. The results of the experiment has shown that the potential difference technique for monitoring crack length is a valuable one and is well suited for use in fatigue testing applications

  14. Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

    International Nuclear Information System (INIS)

    Liaw, P.K.; Logsdon, W.A.; Begley, J.A.

    1989-01-01

    The fatigue crack growth rate (FCGR) properties of SA508 Cl 2a and SA533 Gr A Cl 2 pressure vessel steels and the corresponding automatic submerged arc weldments were developed in a high-temperature pressurized water (HPW) environment at 288 degrees C (550 degrees F) and 7.2 MPa (1044 psi) at load ratios of 0.20 and 0.50. The properties were generally conservative compared to American Society of Mechanical Engineers Section XI water environment reference curve. The growth rate of fatigue cracks in the base materials, however, was faster in the HPW environment than in a 288 degrees C (550 degrees F) base line air environment. The growth rate of fatigue cracks in the two submerged arc weldments was also accelerated in the HPW environment but to a lesser degree than that demonstrated by the base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials compared the weldments attributed to a different sulfide composition and morphology

  15. Stereofractographic investigation of static start and dynamic jump of a fatigue crack in pressure vessel steel

    International Nuclear Information System (INIS)

    Stepanenko, V.A.; Shtukaturova, A.S.; Yasnij, P.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti)

    1983-01-01

    Results of investigaytion have been discussed ipto the effect of certain temperature-force factors on regularities in the formation of stretch zones during the crack initiation static and transition zones at crack jumps in the process of cyclic loading. The 15Kh2NMFA pressure vessel steel has been investigated. The steel fracture toughnesKub(Ic) has been determined testing s the specimens for excentric stretching or a bending through an angle. It has been shown that transition zones in a front of fatique cracks at the jump beginning and end are formed through the shift mechanism owing to the material separation along the maximum failure zone contour, i.e. along the plastic zone contour in a crack vertex. This is the mait difference of regularities in the formation of the transition zones during fatique crack jumps from stretching zones formed through the break-away mechanism of crack vertex bluntness during its static move. It is noted that a final conclusion on the mechanism of transition zone formation during fartique crack jumps allows one to perform systematic investigation into the plastic zone configuration in a fatique crack verteX and stereofractographic measurement of two identically conjugate jump surfaces on opposite fractures of the same samples

  16. Fatigue crack growth characteristics of the pressure vessel steel SA 508 Cl. 3 in various environments

    International Nuclear Information System (INIS)

    Lee, S. G.; Kim, I. S.; Park, Y. S.; Kim, J. W.; Park, C. Y.

    2001-01-01

    Fatigue tests in air and in room temperature water were performed to obtain comparable data and stable crack measuring conditions. In air environment, fatigue crack growth rate was increased with increasing temperature due to an increase in crack tip oxidation rate. In room temperature water, the fatigue crack growth rate was faster than in air and crack path varied on loading conditions. In simulated light water reactor (LWR) conditions, there was little environmental effect on the fatigue crack growth rate (FCGR) at low dissolved oxygen or at high loading frequency conditions. While the FCGR was enhanced at high oxygen condition, and the enhancement of crack growth rate increased as loading frequency decreased to a critical value. In fractography, environmentally assisted cracks, such as semi-cleavage and secondary intergranular crack, were found near sulfide inclusions only at high dissolved oxygen and low loading frequency condition. The high crack growth rate was related to environmentally assisted crack. These results indicated that environmentally assisted crack could be formed by the Electrochemical effect in specific loading condition

  17. The near-threshold high R-ratio fatigue crack growth characteristics of SA508 cl III reactor pressure vessel steel

    International Nuclear Information System (INIS)

    Achilles, R.D.; Bulloch, J.H.

    1989-01-01

    This paper describes the effect of frequency and environment on the near-threshold fatigue crack growth behaviour of SA508 cl III reactor pressure vessel (RPV) steel. The study has shown that in the near-threshold regime microstructure and environment markedly affect fatigue crack growth behaviour. In an aqueous environment, fatigue crack growth behaviour became even more sensitive to microstructure, and the fatigue crack growth rate increased by a factor of four in the case of the 3Hz test, while that for the 0.3Hz test was increased by a factor of approximately sixteen. This environmental enhancement manifested itself in the form of intergranular failure. For the 0.3Hz test the percentage intergranular failure decreased from 18% to <1% with an increase in ΔK level. The transition from microstructure-sensitive to microstructure-insensitive occurs when the cyclic plastic zone size is of the order of the prior austenite grain size. (author)

  18. The reactor vessel steels

    International Nuclear Information System (INIS)

    Bilous, W.; Hajewska, E.; Szteke, W.; Przyborska, M.; Wasiak, J.; Wieczorkowski, M.

    2005-01-01

    In the paper the fundamental steels using in the construction of pressure vessel water reactor are discussed. The properties of these steels as well as the influence of neutron irradiation on its degradation in the time of exploitation are also done. (authors)

  19. Reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Van De Velde, J.; Fabry, A.; Van Walle, E.; Chaouuadi, R.

    1998-01-01

    Research and development activities related to reactor pressure vessel steels during 1997 are reported. The objectives of activities of the Belgian Nuclear Research Centre SCK/CEN in this domain are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate a methodology on a broad database; (3) to achieve regulatory acceptance and industrial use

  20. Reactor Pressure Vessel Steels

    Energy Technology Data Exchange (ETDEWEB)

    Van de Velde, J.; Fabry, A.; Van Walle, E.; Chaoudi, R

    1998-07-01

    SCK-CEN's R and D programme on Reactor Pressure Vessel (RPV) Steels in performed in support of the RVP integrity assessment. Its main objectives are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate the applied methodology on a broad database; (3) to achieve regulatory acceptance and industrial use. Progress and achievements in 1999 are reported.

  1. Residual Stress Estimation and Fatigue Life Prediction of an Autofrettaged Pressure Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kyung Jin; Kim, Eun Kyum; Koh, Seung Kee [Kunsan Nat’l Univ., Kunsan (Korea, Republic of)

    2017-09-15

    Fatigue failure of an autofrettaged pressure vessel with a groove at the outside surface occurs owing to the fatigue crack initiation and propagation at the groove root. In order to predict the fatigue life of the autofrettaged pressure vessel, residual stresses in the autofrettaged pressure vessel were evaluated using the finite element method, and the fatigue properties of the pressure vessel steel were obtained from the fatigue tests. Fatigue life of a pressure vessel obtained through summation of the crack initiation and propagation lives was calculated to be 2,598 cycles for an 80% autofrettaged pressure vessel subjected to a pulsating internal pressure of 424 MPa.

  2. Fatigue Strength of Weathering Steel

    Czech Academy of Sciences Publication Activity Database

    Kunz, Ludvík; Lukáš, Petr; Klusák, Jan

    2012-01-01

    Roč. 18, č. 1 (2012), s. 18-22 ISSN 1392-1320 Grant - others:GA MPO(CZ) FT/TA5/076 Institutional support: RVO:68081723 Keywords : fatigue of weathering steel * corrosion pits * fatigue notch factor Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.522, year: 2012

  3. The Change of the Seebeck Coefficient Due to Neutron Irradiation and Thermal Fatigue of Nuclear Reactor Pressure Vessel Steel and its Application to the Monitoring of Material Degradation

    International Nuclear Information System (INIS)

    Niffenegger, M.; Reichlin, K.; Kalkhof, D.

    2002-05-01

    The monitoring of material degradation, that might be caused by neutron irradiation and thermal fatigue, is an important topic in lifetime extension of nuclear power plants. We therefore investigated the application of the Seebeck effect for determining material degradation of common reactor pressure vessel steel. The Seebeck coefficient (SC) of several irradiated Charpy specimens made from Japanese JRQ-steel were measured. The specimens suffered a fluence from 0 up to 4.5 x 10 19 neutrons per cm 2 with energies higher than 1 MeV. The measured changes of the SC within this range were about 500 nV, increasing continuously in the range under investigation. Some indications of saturation appeared at fluencies larger than 4.55 x 10 19 neutrons per cm 2 . We obtained a linear dependency between the SC and the temperature shift ΔT 41 of the Charpy-Energy- Temperature curve which is widely used to characterize material embrittlement. Similar measurements were performed on specimens made from the widely used austenitic steel X6CrNiTi18-10 (according to DIN 1.4541) that were fatigued by applying a cyclic strain amplitude of 0.28%. For this kind of fatigue the observed change of SC was somewhat smaller than for the irradiated specimens. Further investigations were made to quantify the size of the gage volume in which the thermoelectric power is generated. It appeared that the information gathered from a Thermo Electric Power (TEP) measurement is very local. To overcome this problem we propose a novel TEP-method using a Thermoelectric Scanning Microscope (TSM). We finally conclude that the change of the SC has a potential for monitoring of material degradation due to neutron irradiation and thermal fatigue, but it has to be taken into account that several influencing parameters could contribute to the TEP in either an additional or extinguishing manner. A disadvantage of the method is the requirement of a clean surface without any oxide layer. A part of this disadvantage can

  4. Crack behaviour of ferritic pressure vessels steels in oxygenated high temperature water under transient loadings. Crack corrosion phase 2. Crack development and fatigue. Final report

    International Nuclear Information System (INIS)

    Weissenberg, Thomas

    2014-03-01

    Using the example of the ferritic steels 22NiMoCr3-7 and 15MnNi6-3 representative for Nuclear Power Plants experimental data for the evaluation of the influence of the light water reactor (LWR) coolant environment and postulated chloride contaminations on crack development and fatigue have been determined in order to verify and extend the basis for a reliable estimation of the residual service life of reactor components. The aim of the research project was the investigation of the environmental effects at low strain rate conditions and the determination of the fatigue life under cyclic loading at uniaxial and multiaxial stress state. The quasi-static tensile tests (Constant Extension Rate Test, CERT) were performed using 3 low strain rates, each differing by about one order of magnitude (2.5.10 -3 , 3.1.10 -4 and 2.3.10 -5 %/s). The low cycle fatigue (LCF) experiments were conducted applying alternating tensile-compression loading with strain amplitudes of 0.3, 0.5 and 0.9 % at strain rates of 0.1 and 0.01 %/s (tests in air primarily 0.1 %/s). The cyclic notched tensile tests were carried out with a nominal axial strain in the notch root of 0.5 % at a strain rate of 0.1 %/s. The experiments in each case were performed in air, high purity water and chloride containing water at a testing temperature of 240 C, the oxygen content of the liquid medium was set to 0.4 ppm (simulated boiling water reactor coolant). In the CERT experiments chloride contents of 30, 50 and 100 ppb were applied, in the LCF tests the chloride content was 50 ppb which can be regarded as an upper realistic limit for a postulated chloride contamination of the reactor coolant. All experiments in liquid environment were preceded by a pre-autoclaving phase of at least 100 h in order to allow the formation of a stable oxide layer (magnetite). The testing material 22NiMoCr3-7 was available in form of an original reactor pressure vessel shell primarily designated for the German nuclear power plant

  5. SNPDL work in support of collaborative programmes to study fatigue crack propagation in light water reactor pressure vessel steels

    International Nuclear Information System (INIS)

    McMinn, A.

    1981-07-01

    Work performed at Springfields Nuclear Power Development Laboratories (SNL) in support of United Kingdom and international cooperative groups is described. For the UK collaborative group crack growth tests have been performed on A533-B pressure vessel steel in air at 1 Hz, and in a simulated PWR environment at 1 Hz and 0.0167 Hz, all tests being at a stress ratio (R) of 0.7. Tests were performed at SNL at ambient temperature and pressure. The results showed that enhancements in crack growth rates were obtained because of the aqueous environment and the lower cyclic frequency. Good inter-laboratory agreement was obtained for the air test, indicating that there was little variation in the mechanical control between laboratories. There was also good agreement between the results from laboratories where tests were performed under high temperature wet conditions at 1 Hz. SNL room temperature data demonstrated an effect of temperature, as the crack growth rates found were up to a factor of four lower than the high temperature data. Although crack growth could be maintained at 0.0167 Hz and low cyclic stress intensity levels at ambient temperature, this was not found to be possible by the laboratories performing the test at 288 0 C. The first international 'round robin' test at R = 0.2 and 0.0167 Hz (1 cycle/min) in an aqueous environment gave a significant amount of scatter in the results. (author)

  6. Corrosion fatigue of steels

    International Nuclear Information System (INIS)

    Spaehn, H.; Wagner, G.H.

    1976-01-01

    Corrosion fatigue phenomena can be classified into two main groups according to the electrochemical state of the metal surface in the presence of electrolytes: the active and the passive state with an important sub-group of corrosion fatigue in the unstable passive state. The allowable stress for structures exposed to the conjoint action of corrosion and fatigue is influenced by many factors: kind of media, number of cycles, frequency, mean stress, size, notches, loading mode, alloy composition and mechanical strength. A critical literature review shows contradictory results if a classification by the electrochemical surface state is not applied. Case histories and counter measures illustrate the practical importance of corrosion fatigue in many branches of industry as well as the urgent need for a better knowledge about the mutual influence of the phenomena to get rules by which the engineer can appraise the risk of corrosion fatigue. (orig.) [de

  7. Development of PWR pressure vessel steels

    International Nuclear Information System (INIS)

    Druce, S.; Edwards, B.

    1982-01-01

    Requirements to be met by vessel steels for pressurized water reactors are analyzed. Chemicat composition of low-alloyed steels, mechanical properties of sheets and forgings made of these steels and changes in the composition and properties over the wall thickness of the reactor vessel are presented. Problems of the vessel manufacturing including welding and heat treatment processes of sheets and forgings are considered. Special attention is paid to steel embrittlement during vessel fabrication and operation (radiation embrittlement, thermal embrittlement). The role of non-metal inclusions and their effect on anisotropy of fracture toughness is discussed. Possible developments of vessel steels and procedures for producing reactor vessels are reviewed

  8. Development of PWR pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Druce, S.; Edwards, B.

    1982-01-01

    Requirements to be met by vessel steels for pressurized water reactors are analyzed. Chemicat composition of low-alloyed steels, mechanical properties of sheets and forgings made of these steels and changes in the composition and properties over the wall thickness of the reactor vessel are presented. Problems of the vessel manufacturing including welding and heat treatment processes of sheets and forgings are considered. Special attention is paid to steel embrittlement during vessel fabrication and operation (radiation embrittlement, thermal embrittlement). The role of non-metal inclusions and their effect on anisotropy of fracture toughness is discussed. Possible developments of vessel steels and procedures for producing reactor vessels are reviewed.

  9. Fatigue evaluation in reactor vessel components

    International Nuclear Information System (INIS)

    Mattar Neto, Miguel; Miranda, Carlos A. de J.

    1994-01-01

    This paper presents a sequence of increasing complexity forms of evaluating fatigue damage of nuclear pressure vessel components caused by cycling loadings. Examples are included in order to illustrate such procedures. (author)

  10. Fatigue and fracture behavior of low alloy ferritic forged steels

    International Nuclear Information System (INIS)

    Chaudhry, V.; Sharma, A.K.; Muktibodh, U.C.; Borwankar, Neeraj; Singh, D.K.; Srinivasan, K.N.; Kulkarni, R.G.

    2016-01-01

    Low alloy ferritic steels are widely used in nuclear industry for the construction of pressure vessels. Pressure vessel forged low alloy steels 20MnMoNi55 (modified) have been developed indigenously. Experiments have been carried out to study the Low Cycle Fatigue (LCF) and fracture behavior of these forged steels. Fully reversed strain controlled LCF testing at room temperature and at 350 °C has been carried out at a constant strain rate, and for different axial strain amplitude levels. LCF material behavior has been studied from cyclic stress-strain responses and the strain-life relationships. Fracture behavior of the steel has been studied based on tests carried out for crack growth rate and fracture toughness (J-R curve). Further, responses of fatigue crack growth rate tests have been compared with the rate evaluated from fatigue precracking carried out for fracture toughness (J-R) tests. Fractography of the samples have been carried out to reveal dominant damage mechanisms in crack propagation and fracture. The fatigue and fracture properties of indigenously developed low alloy steel 20MnMoNi55 (modified) steels are comparable with similar class of steels. (author)

  11. Development of PIE techniques for irradiated LWR pressure vessel steels

    International Nuclear Information System (INIS)

    Nishi, Masahiro; Kizaki, Minoru; Sukegawa, Tomohide

    1999-01-01

    For the evaluation of safety and integrity of light water reactors (LWRs), various post irradiation examinations (PIEs) of reactor pressure vessel (RPV) steels and fuel claddings have been carried out in the Research Hot Laboratory (RHL). In recent years, the instrumented Charpy impact testing machine was remodeled aiming at the improvement of accuracy and reliability. By this remodeling, absorbed energy and other useful information on impact properties can be delivered from the force-displacement curve for the evaluation of neutron irradiation embrittlement behavior of LWR-RPV steels at one-time striking. In addition, two advanced PIE technologies are now under development. One is the remote machining of mechanical test pieces from actual irradiated pressure vessel steels. The other is development of low-cycle and high-cycle fatigue test technology in order to clarify the post-irradiation fatigue characteristics of structural and fuel cladding materials. (author)

  12. Metallurgy of steels for PWR pressure vessels

    International Nuclear Information System (INIS)

    Kepka, M.; Mocek, J.; Barackova, L.

    1980-01-01

    A survey and the chemical compositions are presented of reactor pressure vessel steels. The metallurgy is described of steel making for pressure vessels in Japan and the USSR. Both acidic and alkaline open-hearth steel is used for the manufacture of ingots. The leading world manufacturers of forging ingots for pressure vessels, however, exclusively use electric steel. Vacuum casting techniques are exclusively used. Experience is shown gained with the introduction of the manufacture of forging ingots for pressure vessels at SKODA, Plzen. The metallurgical procedure was tested utilizing alkaline open hearths, electric arc furnaces and facilities for vacuum casting of steel. Pure charge raw materials should be used for securing high steel purity. Prior to forging pressure vessel rings, not only should sufficiently big bottoms and heads be removed but also the ingot middle part should be scrapped showing higher contents of impurities and nonhomogeneous structure. (B.S.)

  13. Metallurgy of steels for PWR pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Kepka, M; Mocek, J; Barackova, L [Skoda, Plzen (Czechoslovakia)

    1980-09-01

    A survey and the chemical compositions are presented of reactor pressure vessel steels. The metallurgy is described of steel making for pressure vessels in Japan and the USSR. Both acidic and alkaline open-hearth steel is used for the manufacture of ingots. The leading world manufacturers of forging ingots for pressure vessels, however, exclusively use electric steel. Vacuum casting techniques are exclusively used. Experience is shown gained with the introduction of the manufacture of forging ingots for pressure vessels at SKODA, Plzen. The metallurgical procedure was tested utilizing alkaline open hearths, electric arc furnaces and facilities for vacuum casting of steel. Pure charge raw materials should be used for securing high steel purity. Prior to forging pressure vessel rings, not only should sufficiently big bottoms and heads be removed but also the ingot middle part should be scrapped showing higher contents of impurities and nonhomogeneous structure.

  14. Fatigue in Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    1999-01-01

    types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel with a yield stress of ~ 360-410 MPa or high-strength steel with a yield stress of ~ 810-1010 MPa. The fatigue tests and the fracture mechanics analyses......Fatigue damage accumulation in steel structures under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series have been carried through on various...... have been carried out using load histories, which are realistic in relation to the types of structures studied, i.e. primarily bridges, offshore structures and chimneys. In general, the test series carried through show a significant difference between constant amplitude and variable amplitude fatigue...

  15. Effects of LWR environments on fatigue life of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    SME Boiler and Pressure Vessel Code provides construction of nuclear power plant components. Figure I-90 Appendix I to Section III of the Code specifies fatigue design curves for structural materials. While effects of environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A 106-Gr B carbon steel and A533-Gr B low-alloy steel in water

  16. Irradiation embrittlement of pressure vessel steels

    International Nuclear Information System (INIS)

    Brumovsky, M.; Vacek, M.

    1975-01-01

    A Standard Research Programme on Irradiation Embrittlement of Pressure Vessel Steels was approved by the Coordinating Meeting on the 12th May 1972 at the Working Group on Engineering Aspects of Irradiation Embrittlement of Pressure Vessel Steels. This Working Group was set up by the International Atomic Energy Agency in Vienna. Seven countries with their research institutes agreed on doing irradiation experiments according to the approved programme on steel A533 B from the U.S. HSST Programme. The Czechoslovak contribution covering tensile and impact testing of non-irradiated steel and steel irradiated at 280degC to 1.3 x 10 23 n/m 2 (E above 1 MeV) is presented in this report. As an additional part the same set of experiments was carried out on two additional steels - A 542 and A 543, made in SKODA Works for comparison of their irradiation embrittlement and hardening with A533 B steel. (author)

  17. Effects of LWR coolant environments on fatigue lives of austenitic stainless steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Gavenda, D.J.

    1997-01-01

    The ASME Boiler and Pressure Vessel Code fatigue design curves for structural materials do not explicitly address the effects of reactor coolant environments on fatigue life. Recent test data indicate a significant decrease in fatigue life of pressure vessel and piping materials in light water reactor (LWR) environments. Fatigue tests have been conducted on Types 304 and 316NG stainless steel in air and LWR environments to evaluate the effects of various material and loading variables, e.g., steel type, strain rate, dissolved oxygen (DO) in water, and strain range, on fatigue lives of these steels. The results confirm the significant decrease in fatigue life in water. The environmentally assisted decrease in fatigue life depends both on strain rate and DO content in water. A decrease in strain rate from 0.4 to 0.004%/s decreases fatigue life by a factor of ∼ 8. However, unlike carbon and low-alloy steels, environmental effects are more pronounced in low-DO than in high-DO water. At ∼ 0.004%/s strain rate, reduction in fatigue life in water containing <10 ppb D is greater by a factor of ∼ 2 than in water containing ≥ 200 ppb DO. Experimental results have been compared with estimates of fatigue life based on the statistical model. The formation and growth of fatigue cracks in austenitic stainless steels in air and LWR environments are discussed

  18. High temperature fatigue properties of the 316 FR steel

    International Nuclear Information System (INIS)

    Kobayashi, Kazuo; Yamaguchi, Koji; Kato, Seiichi; Nishijima, Satoshi; Fujioka, Terutaka; Nakazawa, Takanori; Koto, Hiroyuki; Date, Shingo

    1998-01-01

    Type 316 FR stainless steel has been developed as a candidate material for fast breeder reactor of next century. For the structural integrity design of high temperature components including reactor vessel, long-term data and analysis method are investigated for the new 316 FR steel especially to evaluate its time-dependent low-cycle fatigue behavior. The present paper reports dependencies of fatigue life on the strain rate from 10 -2 to 10 -5 s -1 , and on the temperature dependencies from 500degC to 600degC. Data are analyzed by a parametric method formerly proposed by the authors. It is shown that the method has a good predictability of the fatigue life up to very low strain rate of 10 -6 s -1 . (author)

  19. Niobium Application, Metallurgy and Global Trends in Pressure Vessel Steels

    Science.gov (United States)

    Jansto, Steven G.

    Niobium-containing high strength steel materials have been developed for a variety of pressure vessel applications. Through the application of these Nb-bearing steels in demanding applications, the designer and end user experience improved toughness at low temperature, excellent fatigue resistance and fracture toughness and excellent weldability. These enhancements provide structural engineers the opportunity to further improve the pressure vessel design and performance. The Nb-microalloy alloy designs also result in reduced operational production cost at the steel operation, thereby embracing the value-added attribute Nb provides to both the producer and the end user throughout the supply chain. For example, through the adoption of these Nb-containing structural materials, several design-manufacturing companies are considering improved designs which offer improved manufacturability, lower overall cost and better life cycle performance.

  20. Fatigue damage of steel components

    DEFF Research Database (Denmark)

    Fæster, Søren; Zhang, Xiaodan; Huang, Xiaoxu

    2014-01-01

    Railway rails and the inner ring in roller bearings in wind turbines are both experiencing steel-to-steel contact in small areas with huge loads resulting in extremely high stresses in the base materials......Railway rails and the inner ring in roller bearings in wind turbines are both experiencing steel-to-steel contact in small areas with huge loads resulting in extremely high stresses in the base materials...

  1. Corrosion fatigue crack growth of pressure vessel welds in PWR environment

    International Nuclear Information System (INIS)

    Bamford, W.H.; Ceschini, L.J.; Moon, D.M.

    1983-01-01

    The fatigue crack growth rate behavior of several pressure vessel steel welds in PWR environment is discussed. The behavior is compared with associated heat-affected zone behavior, and with comparable base metal results. The welds show different degrees of susceptibility to the environmental influence, and this is discussed in some detail, along with fractographic observations on the tested specimens

  2. Internal Friction of Pressure Vessel Steel Embrittlement

    International Nuclear Information System (INIS)

    Van Ouytsel, K.

    2001-01-01

    The contribution consists of an abstract of a PhD thesis. The thesis contains a literature study, a description of the construction details of a new inverted torsion pendulum. This device was designed to investigate pressure-vessel steels at high amplitudes (10 -4 to 10 -2 ) and over a wide temperature range (90-700K) at approximately 1 Hz in the irradiated condition. Results of measurements on a variety of reactor pressure vessel steels by means of the torsion penduli are reported and interpreted

  3. Reactor Structural Materials: Reactor Pressure Vessel Steels

    International Nuclear Information System (INIS)

    Chaouadi, R.

    2000-01-01

    The objectives of SCK-CEN's R and D programme on Rector Pressure Vessel (RPV) Steels are:(1) to complete the fracture toughness data bank of various reactor pressure vessel steels by using precracked Charpy specimens that were tested statically as well as dynamically; (2) to implement the enhanced surveillance approach in a user-friendly software; (3) to improve the existing reconstitution technology by reducing the input energy (short cycle welding) and modifying the stud geometry. Progress and achievements in 1999 are reported

  4. Strength gradient enhances fatigue resistance of steels

    Science.gov (United States)

    Ma, Zhiwei; Liu, Jiabin; Wang, Gang; Wang, Hongtao; Wei, Yujie; Gao, Huajian

    2016-02-01

    Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch’s tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.

  5. Thermal embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Corwin, W.R.; Nanstad, R.K.; Alexander, D.J.; Stoller, R.E.; Wang, J.A.; Odette, G.R.

    1995-01-01

    As a result of observations of possible thermal embrittlement from recent studies with welds removed from retired steam generators of the Palisades Nuclear Plant (PNP), an assessment was made of thermal aging of reactor pressure vessel (RPV) steels under nominal reactor operating conditions. Discussions are presented on (1) data from the literature regarding relatively low-temperature thermal embrittlement of RPV steels; (2)relevant data from the US power reactor-embrittlement data base (PR-EDB); and (3)potential mechanisms of thermal embrittlement in low-alloy steels

  6. Fatigue of coated and laser hardened steels

    International Nuclear Information System (INIS)

    La Cruz, P. de.

    1990-01-01

    In the present work the effect of ion nitriding, laser hardening and hot dip galvanizing upon the fatigue limit and notch sensitivity of a B-Mn Swedish steel SS 2131 have been investigated. The fatigue tests were performed in plane reverse bending fatigue (R=1). The quenched and tempered condition was taken as the reference condition. The microstructure, microhardness, fracture surface and coating appearance of the fatigue surface treated specimens were studied. Residual stress and retained austenite measurements were also carried out. It was found that ion nitriding improves the fatigue limit by 53 % for smooth specimens and by 115 % for notched specimens. Laser hardening improves the fatigue limit by 18 % and 56 % for smooth and notched specimen respectively. Hot dip galvanizing gives a slight deterioration of the fatigue limit (9 % and 10 % for smooth and notched specimen respectively). Ion nitriding and laser hardening decrease the value of the notch sensitivity factor q by 78 % and 65 % respectively. Hot dip galvanizing does not modify it. A simple schematic model based on a residual stress distribution, has been used to explain the different effects. It seems that the presence of the higher compressive residual stresses and the higher uniformity of the microstructure may be the causes of the better fatigue performance of ion nitrided specimens. (119 refs.) (author)

  7. Evaluation of fatigue damage of pressure vessel materials by observation of microstructures

    International Nuclear Information System (INIS)

    Yoshida, Kazuo

    1994-01-01

    As the important factor as the secular change mode of pressure vessel materials, there is fatigue damage. In USA, there is the move to use LWRs by extending their life, and it becomes necessary to show the soundness of the structures of machinery and equipment for long period. For exactly evaluating the soundness of the structures of machinery and equipment, it is important to clarify the degree of secular deterioration of the materials. In this report, by limiting to the fatigue damage of LWR pressure vessel steel, the method of grasping the change of microstructure and the method of estimating the degree of fatigue damage from the change of microstructure are shown. The change of microstructure arising in materials due to fatigue advances in the following steps, namely, the multiplication of dislocations, the tangling of dislocations, the formation of cell structure, the turning of cells, the formation of microcracks, the growth of cracks and fracture. In the case of pressure vessel steel, due to the quenching and tempering, the cell structure is formed from the beginning, and the advance of fatigue is recognized as the increase of the turning angle of cell structures. The detection of fatigue damage by microstructure is reported. (K.I.)

  8. Underclad cracks growth under fatigue loading in stainless steel cladding

    International Nuclear Information System (INIS)

    Bernard, J.L.; Bodson, F.; Doule, A.; Slama, G.; Bramat, M.; Doucet, J.P.; Maltrud, F.

    1981-01-01

    Hydrogen induced cracks have been found in HAZ of PWR vessel nozzles under stainless steel cladding. Fatigue tests were performed to collect a large amount of data on the possible propagation of this type of flaws. Tests were conducted in two steps. The aim of the first step was to set up the experimental equipment and to device an adequate method for following cracks during fatigue loading. Clad plates with electroerosion machined slots were used for this purpose. The second step was then undertaken with material taken out of an actual nozzle containing hydrogen induced cracks in the HAZ under stainless steel cladding or flaws simulated by electroerosion machined slots. The test loadings were comparable to in service loadings of the nozzles. Special attention was taken to get representative R ratios. Again for the sake of representativity, the tests were performed at 300 0 C (In service temperature) and the hydrotest was simulated. The main results are: It was possible to follow the whole failure process by combining non-destructive examinations during fatigue testing and fractographic observations of broken specimens. Different striation patterns, before and after air has penetrated the actual embedded cracks were observed. Numerical simulation of fatigue crack growth of actual or simulated defects were consistent with experimental data, provided mainly that defect shape, effect of R ratio and of environment were taken into account. (orig.)

  9. Application of fracture mechanics to fatigue in pressure vessels

    International Nuclear Information System (INIS)

    Ghavami, K.

    1982-01-01

    The methods of application of fracture mechanics to predict fatigue crack propagation in welded structures and pressure vessels are described with the following objectives: i) To identify the effect of different variables such as crack tip plasticity, free surface, finite plate thickness, stress concentration and type of the structure, on the magnitude of stress intensity factor K in Welded joint. ii) To demonstrate the use of fracture mechanics for analysing fatigue crack propagation data. iii) To show how a law of fatigue crack propagation based on fracure mechanics, may be used to predict fatigue behavior of welded structures such as pressure vessel. (Author) [pt

  10. Influence of Fretting on Flexural Fatigue of 304 Stainless Steel and Mild Steel

    National Research Council Canada - National Science Library

    Bill, Robert

    1978-01-01

    Fretting fatigue experiments conducted on 304 stainless steel using a flexural-fatigue test arrangement with bolted-on fretting pads have demonstrated that fatigue life is reduced by at least a factor...

  11. Integrity of Magnox reactor steel pressure vessels

    International Nuclear Information System (INIS)

    Flewitt, P.E.J.; Williams, G.H.; Wright, M.B.

    1992-01-01

    The background to the safety assessment of the steel reactor pressure vessels for Magnox power stations is reviewed. The evolved philosophy adopted for the 1991 safety cases prepared for the continued operation of four Magnox power stations operated by Nuclear Electric plc is described, together with different aspects of the multi-legged integrity argument. The main revisions to the materials mechanical property data are addressed together with the assessment methodology adopted and their implications for the overall integrity argument formulated for the continued safe operation of these reactor pressure vessels. (author)

  12. Fatigue fracture modes of a stainless steel

    International Nuclear Information System (INIS)

    Pacheco, D.J.; Souza e Silva, A.S. de; Monteiro, S.N.

    1977-01-01

    The influence of strain hardening and martensite phase transformation on the fatigue fracture regions (pulsative tension) of a Stainless Steel type AISI 316 was investigated. This lead to the conclusion that the greater austenite strain hardening level only favours the occurrence of a brittle fracture. Also, in as much as the static induced martensite is concerned, a direct influence on the failure process was not observed, whereas, apparently, the one transformed under cyclic loading has no contribution to the rupture mechanisms. (author) [pt

  13. Fatigue-Prone Details in Steel Bridges

    Directory of Open Access Journals (Sweden)

    Mohsen Heshmati

    2012-11-01

    Full Text Available This paper reviews the results of a comprehensive investigation including more than 100 fatigue damage cases, reported for steel and composite bridges. The damage cases are categorized according to types of detail. The mechanisms behind fatigue damage in each category are identified and studied. It was found that more than 90% of all reported damage cases are of deformation-induced type and generated by some kind of unintentional or otherwise overlooked interaction between different load-carrying members or systems in the bridge. Poor detailing, with unstiffened gaps and abrupt changes in stiffness at the connections between different members were also found to contribute to fatigue cracking in many details.

  14. High cycle fatigue of austenitic stainless steels

    International Nuclear Information System (INIS)

    Gauthier, J.P.; Lehmann, D.; Picker

    1990-01-01

    This study concerns the evaluation of material data to be used in LMFBR design codes. High cycle fatigue properties of three austenitic stainless steels are evaluated: type AISI 316 (UKAEA tests), type AISI 316L (CEA tests) and type AISI 304 (Interatom tests). The data on these steels comprised some 550 data points from 14 casts. This data set covered a wide range of testing parameters: temperature from 20-625 0 C, frequency from 1-20 000 Hz, constant amplitude and random fatigue loading, with and without mean stress, etc. However, the testing conditions chosen by the three partners differed considerably because they had been fixed independently and not harmonized prior to the tests. This created considerable difficulties for the evaluations. Experimental procedures and statistical treatments used for the three subsets of data are described and discussed. Results are presented in tables and graphs. Although it is often difficult to single out the influence of each parameter due to the different testing conditions, several interesting conclusions can be drawn: The HCF properties of the three steels are consistent with the 0.2% proof stress, the fatigue limit being larger than the latter at temperatures above 550 0 C. The type 304 steel has lower tensile properties than the two other steels and hence also lower HCF properties. Parameters which clearly have a significant effect of HCF behaviour are mean stress or R-ratio (less in the non-endurance region than in the endurance region), temperature, cast or product. Other parameters have probably a weak or no effect but it is difficult to conclude due to insufficient data: environment, specimen orientation, frequency, specimen geometry

  15. Biaxial Loading Tests for steel containment vessel

    Energy Technology Data Exchange (ETDEWEB)

    Miyagawa, T. [Nuclear Power Engineering Corp., Tokyo (Japan); Wright, D.J.; Arai, S.

    1999-07-01

    The Nuclear Power Engineering Corporation (NUPEC) has conducted a 1/10 scale of the steel containment vessel (SCV) test for the understanding of ultimate structural behavior beyond the design pressure condition. Biaxial Loading Tests were supporting tests for the 1/10 scale SCV model to evaluate the method of estimating failure conditions of thin steel plates under biaxial loading conditions. The tentative material models of SGV480 and SPV490 were obtained. And the behavior of SGV480 and SPV490 thin steel plates under biaxial loading conditions could be well simulated by FE-Analyses with the tentative material models and Mises constitutive law. This paper describes the results and the evaluations of these tests. (author)

  16. Biaxial Loading Tests for steel containment vessel

    International Nuclear Information System (INIS)

    Miyagawa, T.; Wright, D.J.; Arai, S.

    1999-01-01

    The Nuclear Power Engineering Corporation (NUPEC) has conducted a 1/10 scale of the steel containment vessel (SCV) test for the understanding of ultimate structural behavior beyond the design pressure condition. Biaxial Loading Tests were supporting tests for the 1/10 scale SCV model to evaluate the method of estimating failure conditions of thin steel plates under biaxial loading conditions. The tentative material models of SGV480 and SPV490 were obtained. And the behavior of SGV480 and SPV490 thin steel plates under biaxial loading conditions could be well simulated by FE-Analyses with the tentative material models and Mises constitutive law. This paper describes the results and the evaluations of these tests. (author)

  17. Fatigue crack growth and fracture behavior of bainitic rail steels.

    Science.gov (United States)

    2011-09-01

    "The microstructuremechanical properties relationships, fracture toughness, fatigue crack growth and fracture surface morphology of J6 bainitic, manganese, and pearlitic rail steels were studied. Microstructuremechanical properties correlation ...

  18. A preliminary bending fatigue spectrum for steel monostrand cables

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2011-01-01

    This paper presents the results of the experimental study on the bending fatigue resistance of high-strength steel monostrand cables. From the conducted fatigue tests in the high-stress, low-cycle region, a preliminary bending fatigue spectrum is derived for the estimation of monostrand cable...... service life expectancy. The presented preliminary bending fatigue spectrum of high-strength monostrands is currently unavailable in the published literature. The presented results provide relevant information on the bending mechanism and fatigue characteristics of monostrand steel cables in tension...... and flexure and show that localized cable bending has a pronounced influence on the fatigue resistance of cables under dynamic excitations....

  19. Corrosion fatigue behaviour of ion nitrided AISI 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Genel, K. [Sakarya Univ., Adapazari (Turkey). Mech. Eng. Dept.; Demirkol, M.; Guelmez, T. [Faculty of Mechanical Engineering, Istanbul Technical University, Guemuessuyu, 80191, Istanbul (Turkey)

    2000-08-31

    Machine components suffer from corrosion degradation of fatigue characteristics and improvement can be attained by the application of a nitriding treatment, particularly to low alloy steels. In the present study, the effect of ion nitriding on corrosion fatigue performance of AISI 4140 steel has been investigated by conducting a series of rotary bending corrosion fatigue tests at 95 Hz, in 3% NaCl aqueous solution. Hourglass shaped, 4 mm diameter fatigue specimens were ion nitrided at 748 K for 1, 3, 8 and 16 h prior to the tests. It was observed that distinct fatigue limit behaviour of ion nitrided steel in air completely disappeared in corrosive environment besides severe degradation in fatigue characteristics. An improvement reaching to 60% in corrosion fatigue strength can be attained by successive ion nitriding practice based on a fatigue life of 10{sup 7} cycles. An attempt was made to establish an empirical relationship between corrosion fatigue strength and relative case depth, which considers the size of the ion nitrided specimen. It was also determined that a power relationship holds between corrosion fatigue strength and fatigue life of ion nitrided steel. The presence of white layer has resulted in additional improvement in corrosion fatigue resistance, and it was observed that corrosion fatigue cracks were initiated dominantly under the white layer by pit formation mechanism. (orig.)

  20. Corrosion fatigue behaviour of ion nitrided AISI 4140 steel

    International Nuclear Information System (INIS)

    Genel, K.

    2000-01-01

    Machine components suffer from corrosion degradation of fatigue characteristics and improvement can be attained by the application of a nitriding treatment, particularly to low alloy steels. In the present study, the effect of ion nitriding on corrosion fatigue performance of AISI 4140 steel has been investigated by conducting a series of rotary bending corrosion fatigue tests at 95 Hz, in 3% NaCl aqueous solution. Hourglass shaped, 4 mm diameter fatigue specimens were ion nitrided at 748 K for 1, 3, 8 and 16 h prior to the tests. It was observed that distinct fatigue limit behaviour of ion nitrided steel in air completely disappeared in corrosive environment besides severe degradation in fatigue characteristics. An improvement reaching to 60% in corrosion fatigue strength can be attained by successive ion nitriding practice based on a fatigue life of 10 7 cycles. An attempt was made to establish an empirical relationship between corrosion fatigue strength and relative case depth, which considers the size of the ion nitrided specimen. It was also determined that a power relationship holds between corrosion fatigue strength and fatigue life of ion nitrided steel. The presence of white layer has resulted in additional improvement in corrosion fatigue resistance, and it was observed that corrosion fatigue cracks were initiated dominantly under the white layer by pit formation mechanism. (orig.)

  1. Modal Based Fatigue Monitoring of Steel Structures

    DEFF Research Database (Denmark)

    Graugaard-Jensen, J.; Brincker, Rune; Hjelm, H. P.

    2005-01-01

    In this paper it is shown how the accumulated fatigue in steel structures can be estimated with high accuracy by continuously measuring the accelerations in a few points of the structure. First step is to obtain a good estimate of the mode shapes by performing a natural input modal analysis. The so...... by applying the mode shapes of the calibrated Finite Element model and strains are obtained using the shape functions for the actual elements. The technique has been applied on a model frame structure in the laboratory and on a wind loaded lattice pylon structure. In both cases the estimated stresses has been...

  2. Results of steel containment vessel model test

    International Nuclear Information System (INIS)

    Luk, V.K.; Ludwigsen, J.S.; Hessheimer, M.F.; Komine, Kuniaki; Matsumoto, Tomoyuki; Costello, J.F.

    1998-05-01

    A series of static overpressurization tests of scale models of nuclear containment structures is being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the US Nuclear Regulatory Commission. Two tests are being conducted: (1) a test of a model of a steel containment vessel (SCV) and (2) a test of a model of a prestressed concrete containment vessel (PCCV). This paper summarizes the conduct of the high pressure pneumatic test of the SCV model and the results of that test. Results of this test are summarized and are compared with pretest predictions performed by the sponsoring organizations and others who participated in a blind pretest prediction effort. Questions raised by this comparison are identified and plans for posttest analysis are discussed

  3. Pressure Vessel Steel Research: Belgian Activities

    International Nuclear Information System (INIS)

    Van Walle, E.; Fabry, A.; Ait Abderrahim, H.; Chaouadi, R.; D'hondt, P.; Puzzolante, J.L.; Van de Velde, J.; Van Ransbeeck, T.; Gerard, R.

    1994-03-01

    A review of the Belgian research activities on Nuclear Reactor Pressure Vessel Steels (RPVS) and on related Neutron Dosimetry Aspects is presented. Born out of the surveillance programmes of the Belgian nuclear power plants, this research has lead to the development of material saving techniques, like reconstitution and miniaturization, and to improved neutron dosimetry techniques. A physically- justified RPVS fracture toughness indexation methodology, supported by micro-mechanistic modelling, is based on the elaborate use of the instrumented Charpy impact signal. Computational tools for neutron dosimetry allow to reduce the uncertainties on surveillance capsule fluences significantly

  4. Pressure Vessel Steel Research: Belgian Activities

    Energy Technology Data Exchange (ETDEWEB)

    Van Walle, E; Fabry, A; Ait Abderrahim, H; Chaouadi, R; D` hondt, P; Puzzolante, J L; Van de Velde, J; Van Ransbeeck, T [Centre d` Etude de l` Energie Nucleaire, Mol (Belgium); Gerard, R [TRACTEBEL, Brussels (Belgium)

    1994-03-01

    A review of the Belgian research activities on Nuclear Reactor Pressure Vessel Steels (RPVS) and on related Neutron Dosimetry Aspects is presented. Born out of the surveillance programmes of the Belgian nuclear power plants, this research has lead to the development of material saving techniques, like reconstitution and miniaturization, and to improved neutron dosimetry techniques. A physically- justified RPVS fracture toughness indexation methodology, supported by micro-mechanistic modelling, is based on the elaborate use of the instrumented Charpy impact signal. Computational tools for neutron dosimetry allow to reduce the uncertainties on surveillance capsule fluences significantly.

  5. Flexural fatigue behavior of steel fiber reinforced concrete structures

    International Nuclear Information System (INIS)

    Chang, G.I.; Chai, W.K.; Park, C.W.; Min, I.K.

    1993-01-01

    In this thesis, the fatigue tests are performed on a series of SFRC (steel fiber reinforced concrete) to investigate the fatigue behavior of SFRC varing with the steel fiber contents and the steel fiber aspect ratios. Thirty SFRC beams are used in this test. The relationships between repeated loading cycle and mid-span deflection of the beams are observed under the three-point loading system. From the test results, the effects of the fiber content and the fiber aspect ratio on the concrete fatigue behavior were studied. According to the regression technique, some empirical formulae for predicting the fatigue strength of SFRC beams are also suggested. (author)

  6. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2008-01-01

    Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...... and variable amplitude fatigue test results. Both the fracture mechanics analysis and the fatigue test results indicate that Miner’s rule, which is normally used in the design against fatigue in steel structures, may give results, which are unconservative, and that the validity of the results obtained from...

  7. Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1998-03-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the code specify fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data indicate that the Code fatigue curves may not always be adequate in coolant environments. This report summarizes work performed by Argonne National Laboratory on fatigue of carbon and low-alloy steels in light water reactor (LWR) environments. The existing fatigue S-N data have been evaluated to establish the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, temperature, orientation, and sulfur content on the fatigue life of these steels. Statistical models have been developed for estimating the fatigue S-N curves as a function of material, loading, and environmental variables. The results have been used to estimate the probability of fatigue cracking of reactor components. The different methods for incorporating the effects of LWR coolant environments on the ASME Code fatigue design curves are presented

  8. Acoustic events during fatigue test of structural steels

    Energy Technology Data Exchange (ETDEWEB)

    Por, Gabor; Fekete, Balazs; Csicso, Gabor; Trampus, Peter [College of Dunaujvaros (Hungary)

    2014-11-01

    Acoustic emission sensors were applied recording noises during low cycle fatigue tests in steel materials. The test specimens were machined from the base metal (15H2MFA) and the anticorrosive cladding metal (08H18N10T) of the VVER-440/V-213 (Russian designed PWR) reactor pressure vessel. During the first period, the measurements were carried out with isothermal condition at 260 C on GLEEBLE 3800 servo-hydraulic thermal-mechanical simulator. The tests were run under uniaxial tension-compression loading with total strain control. The programmed waveform was triangular for all the fatigue tests with the frequency of 0.08 Hz. The cyclic loading was started from the compressed side. It was observed that besides rare acoustic emission events regular 10 msec Acoustic Barkhausen Noise (ABN) burst were recorded due to 50Hz AC current drive for heating and maintaining the constant temperature. The amplitude of MABN was higher under pressure than during relaxing and drawing-out by a factor of 2-5. We have carried out also thermo-mechanical fatigue experiment with the same strain-controlled mechanical cycle and simultaneous thermal cycle between 150 C and 270 C. The total number of cycles was terminated, when the force level necessary for the original elongation had been reduced to 75% of its original value. Visual examination showed always some at least surface cracks after stopping the fatigue test. ABN events registered during the beginning cycle exhibited different spectra from the middle and especially from the last cycles before the end of the test, where also double ABN bursts could be recorded. At the end of the test explicit AE events could be found by a new technique. The most interesting result is the possibility to use ABN for testing reactor materials, which could have practical application for fatigue testing.

  9. Fatigue in Steel Highway Bridges under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, J.A.; Vejrum, Tina

    1997-01-01

    on welded plate test specimens have been carried through. The materials that have been used are either conventional structural steel with a yield stress of ~ 400-410 MPa or high-strength steel with a yield stress of ~ 810-840 MPa.The fatigue tests have been carried out using load histories, which correspond......In the present investigation, fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis.In the experimental part of the investigation, fatigue test series...... to one week's traffic loading, determined by means of strain gage measurements on the orthotropic steel deck structure of the Farø Bridges in Denmark.The test series which have been carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...

  10. Fatigue in Steel Highway Bridges under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, Jette Andkjær

    1999-01-01

    have been carried through. The materials that have been used are either conventional structural steel with a yield stress of f(y) similar to 400-410 MPa or high-strength steel with a yield stress of f(y) similar to 810-840 MPa. The fatigue tests have been carried out using load histories, which......Fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series on welded plate test specimens...... correspond to one week's traffic loading, determined by means of strain gauge measurements on the orthotropic steel deck structure of the Faro Bridges in Denmark. The test series carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...

  11. Fatigue and creep-fatigue in sodium of 316 L stainless-steel

    International Nuclear Information System (INIS)

    Ardellier, A.

    1981-03-01

    The present paper describes test-facility developed to perform low-cycle fatigue and creep-fatigue interaction in sodium on stainless steel - 316 L . Fatigue life in sodium and in air are compared. A beneficial effect in sodium is noted

  12. Study of interaction of fatigue damage and ratcheting. Effect of a tensile primary load on torsion fatigue resistance of stainless steel 304 L at ambient temperature

    International Nuclear Information System (INIS)

    Hakem, N.S.

    1987-01-01

    Effect of ratcheting on fatigue resistance of a stainless steel 304 L, used for reactor vessels, is studied experimentally. Lifetime of samples is reduced if a static constant tensile load (primary loading) is superimposed to cyclic torsion deformations (secondary loading). An equivalent deformation concept is developed to express a criterion of fatigue rupture under primary loading. No effect is noted on the curve of cyclic strain hardening. This fatigue analysis gives no information on cumulated axial deformation. Progressive elongation, observed during testing, is dependent of primary and secondary loading. Rupture is produced by fatigue because cumulated axial deformation is limited ( 4 cycles at rupture cumulated deformation is [fr

  13. Safety of steel vessel Magnox pressure circuits

    International Nuclear Information System (INIS)

    Stokoe, T.Y.; Bolton, C.J.; Heffer, P.J.H.

    1991-01-01

    The maintenance of pressure circuit integrity is fundamental to nuclear safety at the steel vessel Magnox stations. To confirm continued pressure circuit integrity the CEGB, as part of the Long Term Safety Review, has carried out extensive assessment and inspection in recent years. The assessment methods and inspection techniques employed are based on the most modern available. Reactor pressure vessel integrity is confirmed by a combination of arguments including safety factors inferred from the successful pre-service overpressure test, leak-before-break analysis and probabilistic assessment. In the case of other parts of the pressure circuits that are more accessible, comprising the boiler shells and interconnecting gas duct work, in-service inspection is a major element of the safety substantiation. The assessment and inspection techniques and the materials property data have been underpinned for many years by extensive research and development programmes and in-reactor monitoring of representative samples has also been undertaken. The paper summarises the work carried out to demonstrate the long term integrity of the Magnox pressure circuits and provides examples of the results obtained. (author)

  14. Fatigue characteristics of dual-phase steel sheets

    Energy Technology Data Exchange (ETDEWEB)

    Onn, Irwan Herman; Ahmad, Norhayati; Tamin, Mohd Nasir [Universiti Teknologi Malaysia, Skudai (Malaysia)

    2015-01-15

    Fatigue characteristics of dual-phase steel sheets, commonly used in automobile body construction were established. For this purpose, a series of fatigue tests, each at constant stress amplitude were conducted on 1.2 mm-thick, dual-phase DP600 steel sheet specimens with two different load ratios of minimum-to-maximum stress, R = 0.1 and -1. The resulting fatigue behavior is expressed in terms of fatigue strength-life (S-N) curves. Fatigue behavior of the steel sheets in the high-cycle fatigue region can be represented by Basquin's equation with coefficient and exponent value of 921.2 and 0.093, respectively. An endurance limit of 255 MPa is observed. In addition, fatigue strengths of the dual-phase steel sheets display lower magnitude than their bulk counterparts. Effect of mean stress on fatigue behavior of the steel sheets is well predicted by Walker's model. Exponential calibration factor is introduced to the models by SWT, Goodman and Morrow with comparable prediction to the Walker's model.

  15. Investigations into the fatigue behaviour of nuclear grades of austenitic stainless steel

    International Nuclear Information System (INIS)

    Mann, J.

    2015-01-01

    Full text of publication follows. Fatigue is an important problem within the nuclear industry due to the complex combination of thermal and mechanical loading that components experience during the operation of a nuclear reactor. Austenitic stainless steels are widely used within nuclear reactors for a number of applications including piping systems and pressure vessels. A number of studies have shown that austenitic stainless steel components operating within a light water reactor (LWR) environment may experience a significant reduction in fatigue life under certain circumstances, however the precise mechanisms responsible for the reduction are still not fully understood. The effects of environment are included in some fatigue assessment methods, however these are generally considered to be over-conservative and predicted fatigue lifetimes are not reflected well by service experience. This project aims to enhance the understanding of fatigue in both air and LWR environments through the synergistic use of a wide range of different microscopy techniques. It is expected that a better understanding of each of the different stages of fatigue will lead to more accurate fatigue predictions that ultimately result in better and safer lifetime predictions. This paper focuses on introducing the background behind the project, highlighting the current methods for assessing fatigue lifetimes and the motivations for the current research. The results of various initial microscopic investigations are presented, with a focus on a number of novel applications using laser scanning confocal microscopy to perform large scale analyses of fatigue fracture surfaces and test specimen gauge length surfaces. The use of surface replicas in conjunction with laser scanning confocal microscopy is discussed along with its potential applications for the assessment of fatigue damage in in-service components. Initial finite element modelling of crack growth within fatigue test specimens is discussed

  16. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2009-01-01

    of the investigation, fatigue test series with a total of 540 fatigue tests have been carried through on various types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel or high-strength steel. The fatigue tests......Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...... and the fracture mechanics analyses have been carried out using load histories, which are realistic in relation to the types of structures studied, i.e. primarily bridges, offshore structures and chimneys. In general, the test series carried through show a significant difference between constant amplitude...

  17. Seismic Behavior of Fatigue-Retrofitted Steel Frame Piers

    Directory of Open Access Journals (Sweden)

    Kinoshita K.

    2013-01-01

    Full Text Available Fatigue retrofit works have been conducted on severely fatigue damaged beam-to-column connections of existing steel frame bridge piers in Japan. It is clear that retrofit works provides additional stiffness but the significance on the seismic behavior of steel frame piers is not clear. Since fatigue retrofit works have become prevalent, the effect of fatigue retrofit works on the seismic behavior of steel frame piers need to be understood. The objective of this study is therefore to investigate these effects of the retrofit work, especially installation of bolted splices, which is the most common technique. Elasto-plastic finite element earthquake response analyses were carried out. It is shown that the existence of bolted splices may increase seismic demand on the piers when plastic hinge zone is located on the beam. In addition, longer bolted splices using low yield strength steel are proposed to overcome this problem and are shown to give beneficial effects.

  18. Topic 1. Steels for light water reactor pressure vessels

    International Nuclear Information System (INIS)

    Brumovsky, M.; Brynda, J.; Kepka, M.; Barackova, L.; Vacek, M.; Havel, S.; Cukr, B.; Protiva, K.; Petrman, I.; Tvrdy, M.; Hyspecka, L.; Mazanec, K.; Kupca, L.; Brezina, M.

    1980-01-01

    Part 1 of the Proceedings consists of papers on the criteria for the selection and comparison of the properties of steel for pressure vessels and on the metallurgy of the said steels, the selection of suitable material for internal tubing systems, the manufacture of high-alloy steels for WWER components, the mechanical and metallurgical properties of steel 22K for WWER 440 pressure components, and of steel 10MnNi2Mo for the WWER primary coolant circuit, and the metallographic assessment of steel 0Kh18N10T. (J.P.)

  19. Corrosion of vessel steel during its interaction with molten corium

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Granovsky, V.S.; Lopukh, D.B.; Gusarov, V.V.; Martinov, A.P.; Martinov, V.V.; Fieg, G.; Tromm, W.; Bottomley, D.; Tuomisto, H.

    2006-01-01

    This paper is concerned with corrosion of a cooled vessel steel structure interacting with molten corium in air and neutral (nitrogen) atmospheres during an in-vessel retention scenario. The data on corrosion kinetics at different temperatures on the heated steel surface, heat flux densities and oxygen potential in the system are presented. The post-test physico-chemical and metallographic analyses of melt samples and the corium-specimen ingot have clarified certain mechanisms of steel corrosion taking place during the in-vessel melt interaction

  20. Renovation techniques for fatigue cracked orthotropic steel bridge decks

    NARCIS (Netherlands)

    de Jong, F.B.P.

    2007-01-01

    This dissertation presents the research into renovation techniques for orthotropic steel bridge decks. These techniques are needed to solve fatigue problems in the decks of these bridges, as several fatigue cracks have been detected in the deck structure of these bridges the last decade. A

  1. Study on Fatigue Characteristics of High-Strength Steel Welds

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hong Suk; Yoo, Seung Won; Park, Jong Chan [Hyundai Motor Group, Seoul (Korea, Republic of)

    2015-03-15

    High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

  2. Fatigue behaviour of friction welded medium carbon steel and austenitic stainless steel dissimilar joints

    International Nuclear Information System (INIS)

    Paventhan, R.; Lakshminarayanan, P.R.; Balasubramanian, V.

    2011-01-01

    Research highlights: → Fusion welding of dissimilar metals is a problem due to difference in properties. → Solid state welding process such as friction welding is a solution for the above problem. → Fatigue life of friction welded carbon steel and stainless steel joints are evaluated. → Effect of notch on the fatigue life of friction welded dissimilar joints is reported. → Formation of intermetallic is responsible for reduction in fatigue life of dissimilar joints. -- Abstract: This paper reports the fatigue behaviour of friction welded medium carbon steel-austenitic stainless steel (MCS-ASS) dissimilar joints. Commercial grade medium carbon steel rods of 12 mm diameter and AISI 304 grade austenitic stainless steel rods of 12 mm diameter were used to fabricate the joints. A constant speed, continuous drive friction welding machine was used to fabricate the joints. Fatigue life of the joints was evaluated conducting the experiments using rotary bending fatigue testing machine (R = -1). Applied stress vs. number of cycles to failure (S-N) curve was plotted for unnotched and notched specimens. Basquin constants, fatigue strength, fatigue notch factor and notch sensitivity factor were evaluated for the dissimilar joints. Fatigue strength of the joints is correlated with microstructure, microhardness and tensile properties of the joints.

  3. Thermal fatigue cracking of austenitic stainless steels

    International Nuclear Information System (INIS)

    Fissolo, A.

    2001-01-01

    This report deals with the thermal fatigue cracking of austenitic stainless steels as AISI 316 LN and 304 L. Such damage has been clearly observed for some components used in Fast Breeder reactors (FBR) and Pressure Water Reactor (PWR). In order to investigate thermal fatigue, quasi-structural specimen have been used. In this frame, facilities enforcing temperature variations similar to those found under the operation conditions have been progressively developed. As for components, loading results from impeded dilatation. In the SPLASH facility, the purpose was to establish accurate crack initiation conditions in order to check the relevance of the usual component design methodology. The tested specimen is continuously heated by the passage of an electrical DC current, and submitted to cyclic thermal down shock (up to 1000 deg C/s) by means of periodical spraying of water on two opposite specimen faces. The number of cycles to crack initiation N i is deduced from periodic examinations of the quenched surfaces, by means of optical microscopy. It is considered that initiation occurs when at least one 50μm to 150□m long crack is observed. Additional SPLASH tests were performed for N >> N i , with a view to investigate the evolution of a surface multiple cracking network with the number of cycles N. The CYTHIA test was mainly developed for the purpose of assessing crack growth dynamics of one isolated crack in thermal fatigue conditions. Specimens consist of thick walled tubes with a 1 mm circular groove is spark-machined at the specimen centre. During the test, the external wall of the tube is periodically heated by using a HF induction coil (1 MHz), while its internal wall is permanently cooled by flowing water. Total crack growth is derived from post-mortem examinations, whereby the thermal fatigue final rupture surface is oxidized at the end of the test. The specimen is broken afterwards under mechanical fatigue at room temperature. All the tests confirm that

  4. Localized bending fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2012-01-01

    In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement of the st......In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement...... displacement (opening/closing and sliding) of the helically wound wires. Moreover, the results are a step towards understanding the bending fatigue damage mechanisms of monostrand cables....

  5. Experimental studies of oxidic molten corium-vessel steel interaction

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V.

    2001-01-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere

  6. Experimental studies of oxidic molten corium-vessel steel interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V. E-mail: niti-npc@sbor.net; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V

    2001-12-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere.

  7. Low temperature radiation embrittlement for reactor vessel steels

    International Nuclear Information System (INIS)

    Ginding, I.A.; Chirkina, L.A.

    1978-01-01

    General conceptions of cold brittleness of bcc metals are in a review. Considered are experimental data and theoretical representations about the effect of irradiation conditions, chemical composition, phase and structural constitutions, grain size, mechanical and thermomechanical treatments on low-temperature irradiation embrittlement of reactor vessel steels. Presented are the methods for increasing radiation stability of metals (carbon and Cr-Mo steels) used in manufacturing reactor vessels

  8. East/west steels for reactor pressure vessels

    International Nuclear Information System (INIS)

    Davies, M.; Kryukov, A.; Nikolaev, Y.; English, C.

    1997-01-01

    The report consist of three parts dealing with comparison of the irradiation behaviour of 'Eastern' and 'Western' steels, mechanisms of irradiation embrittlement and the role of compositional variations on the irradiation sensitivity of pressure vessels. Nickel, copper and phosphorus are the elements rendering the most essential influence on behaviour of pressure vessel steels under irradiation and subsequent thermal annealing. For WWER-440 reactor pressure vessel (RPV) steels in which nickel content does nor exceed 0.3% the main affecting factors are phosphorous and copper. For WWER-1000 RPV welds in which nickel content generally exceed 1.5% the role of nickel in radiation embrittlement is decisive. In 'Western' type steels main influencing elements are nickel and copper. The secondary role of phosphorus in radiation embrittlement of 'Western' steels is caused by lower relative content compared to 'Eastern' steels. The process of how copper, phosphorus and nickel contents affect the irradiation sensitivity of both types of steel seem to be similar. Some distinctions between the observed radiation effects is apparently caused by differences in the irradiation conditions and ratios of the contents of above mentioned elements in both types of steel. For 'Eastern' RPV steels the dependence of the recovery degree of irradiated steels due to postirradiation thermal annealing id obviously dependent on phosphorus contents and the influence of nickel contents on this process is detectable

  9. Fatigue life of high strength steel for cold forming

    Directory of Open Access Journals (Sweden)

    R. Ulewicz

    2017-01-01

    Full Text Available The article presents the results of fatigue tests carried out on STRENX-type high-strength cold forming steel. For high-cycle fatigue tests carried out using low cycle loading frequencies of around 30 Hz, a ROTOFLEX machine was used. For ultra high-cycle tests, a KAUP-ZU testing machine was employed, which enables fatigue tests to be performed with symetric specimen loading (R = -1 and at a frequency of f ≈ 20 kHz. The relationships σa = f(N were determined experimentally in the high and ultra high-cycle region for STRENX high-strength steel. To determine the fatigue crack initiation mechanism, the fractographic analysis of fatigue fractures was made.

  10. Phase transformation by fatigue in austenitic stainless steel

    International Nuclear Information System (INIS)

    Jo, Y.S.; Kwun, S.I.

    1988-01-01

    The effect of strain induced martensite on the fatigue behavior of AISI 304 austenitic stainless steel was investigated. During low cycle fatigue, the austenitic stainless steel showed a continuous cyclic hardening until fracture. The extent of cyclic hardening increased with decreasing austenite stability. The austenite stability was controlled by different aging time and temperature, which resulted in different carbide morphologies. The fatigue crack propagation rate near ΔK th varied also with the austenite stability inside the plastic zone at the crack up. Especially, the near-threshold fatigue crack propagation rate of the grain boundary carbide precipitated condition was the lowest. This was considered to be due to the roughness induced closure caused by intergranular facet. A new model for the intergranular facet formation and the fatigue crack propagation of grain boundary carbide precipitated condition was proposed. (Author)

  11. Fatigue resistance of Cr-Ni-Mo-V steel

    International Nuclear Information System (INIS)

    Naumchenkov, N.E.; Filimonova, O.V.; Borisov, I.A.

    1985-01-01

    A study was made on the effect of additional alloying (Ni, Ni+Co), stress concentration, surface plastic strain on fatigue resistance of rotor steel of Cr-Ni-Mo-V-composition. It is shown that the steel with decreased carbon content possesses high complex of mechanical properties. Fatigue characteristics are not inferior to similar characteristics of steels of 25KhN3MFA type. Additional alloying of the steel containing 0.11...0.17% C and 4.5...4.7% N:, with niobium separately or niobium and cobalt in combination enabled to improve fatigue resistance of samles up to 25%. Strengthening of stress concentration zones by surface plastic strain is recommended for improving rotor suppporting 'nower under cyclic loading

  12. Application of high strength steel to nuclear reactor containment vessel

    International Nuclear Information System (INIS)

    Susukida, H.; Sato, M.; Takano, G.; Uebayashi, T.; Yoshida, K.

    1976-01-01

    Nuclear reactor containment vessels are becoming larger in size with the increase in the power generating capacity of nuclear power plants. For example, a containment vessel for a PWR power plant with an output of 1,000 MWe becomes an extremely large one if it is made of the conventional JIS SGV 49 (ASTM A 516 Gr. 70) steel plates less than 38 mm in thickness. In order to design the steel containment vessel within the conventional dimensional range, therefore, it is necessary to use a high strength steel having a higher tensile strength than SGV 49 steel, good weldability and a higher fracture toughness and moreover, possessing satisfactory properties without undergoing post-weld heat treatment. The authors conducted a series of verification tests on high strength steel developed by modifying the ASTM A 543 Grade B Class 1 steel with a view to adopting it as a material for the nuclear reactor containment vessels. As the result of evaluation of the test results from various angles, we confirmed that the high strength steel is quite suitable for the manufacture of nuclear reactor containment vessels. (auth.)

  13. Effect of dynamic strain aging on isotropic hardening in low cycle fatigue for carbon manganese steel

    International Nuclear Information System (INIS)

    Huang, Zhi Yong; Chaboche, Jean-Louis; Wang, Qing Yuan; Wagner, Danièle; Bathias, Claude

    2014-01-01

    Carbon–manganese steel A48 (French standard) is used in steam generator pipes of nuclear reactor pressure vessels at high temperatures (about 200 °C). The steel is sensitive to dynamic strain aging in monotonic tensile test and low cycle fatigue test at certain temperature range and strain rate. Its isotropic hardening behavior observed from experiments has a hardening, softening and hardening evolution with the effect of dynamic strain aging. The isotropic hardening model is improved by coupling the dislocation and dynamic strain aging theory to describe the behavior of A48 at 200 °C

  14. Effect of dynamic strain aging on isotropic hardening in low cycle fatigue for carbon manganese steel

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhi Yong, E-mail: huangzy@scu.edu.cn [Sichuan University, School of Aeronautics and Astronautics, No. 29 Jiuyanqiao Wangjiang Road, Chengdu 610064 (China); Chaboche, Jean-Louis [ONERA, DMSM, 29 avenue de la Division Lecerc, F-92320 Chatillon (France); Wang, Qing Yuan [Sichuan University, School of Aeronautics and Astronautics, No. 29 Jiuyanqiao Wangjiang Road, Chengdu 610064 (China); Wagner, Danièle; Bathias, Claude [Université ParisOuest Nanterre La Défense (France)

    2014-01-01

    Carbon–manganese steel A48 (French standard) is used in steam generator pipes of nuclear reactor pressure vessels at high temperatures (about 200 °C). The steel is sensitive to dynamic strain aging in monotonic tensile test and low cycle fatigue test at certain temperature range and strain rate. Its isotropic hardening behavior observed from experiments has a hardening, softening and hardening evolution with the effect of dynamic strain aging. The isotropic hardening model is improved by coupling the dislocation and dynamic strain aging theory to describe the behavior of A48 at 200 °C.

  15. Low cycle thermomechanical fatigue of reactor steels: Microstructural and fractographic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Fekete, Balazs, E-mail: fekete.mm.bme@gmail.com [College of Dunaujvaros, Tancsics 1A, Dunaujvaros H-2400 (Hungary); Department of Applied Mechanics, Budapest University of Technology and Economics, Muegyetem 5, Budapest H-1111 (Hungary); Kasl, Josef; Jandova, Dagmar [Výzkumný a zkušební ústav Plzeň s.r.o., Tylova 1581/46, 316 00 Plzen (Czech Republic); Jóni, Bertalan [College of Dunaujvaros, Tancsics 1A, Dunaujvaros H-2400 (Hungary); Eötvös Loránd University, Egyetem tér 1-3, Budapest H-1053 (Hungary); Misják, Fanni [Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege M. 29-33, Budapest H-1121 (Hungary); Trampus, Peter [College of Dunaujvaros, Tancsics 1A, Dunaujvaros H-2400 (Hungary)

    2015-07-29

    The fatigue life of the structural materials 15Ch2MFA (CrMoV-alloyed ferritic steel) and 08Ch18N10T (CrNi-alloyed austenitic steel) of a VVER-440 reactor pressure vessel were investigated under fully reversed total strain controlled low cycle fatigue tests. The measurements were carried out in isothermal conditions at 260 °C and with thermal-mechanical conditions in the range 150–270 °C using a GLEEBLE-3800 servo-hydraulic thermal-mechanical simulator. The low cycle fatigue results were evaluated with the Coffin–Manson law, and the parameters of the Ramberg–Osgood stress–strain relation were investigated. Fracture mechanics behavior was observed using scanning electron microscopic analysis of the crack shapes and fracture surfaces. Crack propagation was assessed in relation to the actual crack size and the loading level. Interrupted fatigue tests were also carried out to investigate the kinetics of the fatigue evolution of the materials. Microstructural evaluation of the samples was performed using light, scanning and transmission electron microscopy as well as X-ray diffraction, and measurement of dislocations was completed using TEM and XRD. The course of dislocation density in relation to cumulative usage factor was similar for both steels. However, the nature and distribution of dislocations were different in the individual steels and this resulted in different mechanical behaviors. The nature of the fracture surfaces of both steels appeared similar despite differences in dislocation arrangement. The distances between striation lines initially increased with increasing crack length and then became saturated. The low cycle fatigue behavior investigated can provide a reference for the remaining life assessment and lifetime extension analysis of nuclear power plant components.

  16. Corrosion fatigue behaviors of steel wires used in coalmine

    International Nuclear Information System (INIS)

    Wang, Songquan; Zhang, Dekun; Chen, Kai; Xu, Linmin; Ge, Shirong

    2014-01-01

    Highlights: • The CF life of steel wire in acid solution is the shortest. • The fatigue source zone showed dimple morphology when coupled with anode potential. • The area of dimple increases with the increase of the applied anode potential. • The strong cathode potential cannot reduce the CF life of the smooth steel wire. • The hydrogen impacted mainly on the plastic deformation of the wire surface. - Abstract: The corrosion fatigue (CF) behaviors of the mining steel wire in different solutions at different applied polarization potentials were investigated in this paper. The surfaces and fracture morphologies of the steel wire at different applied potentials were observed by scanning electron microscope (SEM). The results showed that the CF life of steel wire in acid solution is the shortest. Moreover, the strong anodic polarization potential greatly reduced the CF life of steel wire, while the strong cathode potential did not reduce the CF life. For the smooth steel wire, the hydrogen impacted mainly on the plastic deformation of the wire surface. There was obvious dimple in the fatigue source zone of the wire when coupled with anode potential, and the area of the dimple increased with the increase of the applied anode potential. Conversely, the fatigue source zone of the fracture was relatively smooth at cathode polarization potential, which indicated that the crack propagation followed the mechanism of hydrogen induced cracking

  17. Modeling irradiation embrittlement in reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Odette, G.R.

    1998-01-01

    As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 10, numerical modeling of irradiation embrittlement in reactor vessel steels are introduced. Physically-based models are developed and their role in advancing the state-of-the-art of predicting irradiation embrittlement of RPV steels is stressed

  18. Microstructural evolution in neutron irradiated reactor pressure vessel steels

    International Nuclear Information System (INIS)

    English, C.A.; Phythian, W.J.

    1998-01-01

    As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. The microstructural evolution in neutron irradiated reactor pressure vessel steels is described. The damage mechanisms are elaborated and techniques for examining the microstructure are suggested. The importance of the initial damage event is analysed, and the microstructural evolution in RPV steels is examined

  19. Structural characterization and magnetic properties of steels subjected to fatigue

    International Nuclear Information System (INIS)

    Lo, C.C.H.; Tang, F.; Biner, S.B.; Jiles, D.C.

    2000-01-01

    Studies have been made on the effects of residual stress and microstructure on the variations of magnetic properties of steels during fatigue. Strain-controlled fatigue tests have been conducted on 0.2wt% C steel samples which were (1) cold-worked (2) cold-worked and annealed at 500 deg. C to relieve residual stress, and (3) annealed at 905 deg. C to produce a ferrite/pearlite structure. The changes of surface microstructure were studied by SEM replica technique. The dislocation structures of samples fatigued for different numbers of cycle were studied by TEM. In the initial stage of fatigue coercivity was found to behave differently for samples which have different residual stress levels. In the intermediate stage the magnetic hysteresis parameters became stable as the dislocation cell structure developed in the samples. In the final stage the magnetic parameters decreased dramatically. The decrease rate is related to the propagation rate of fatigue cracks observed in the SEM study, which was found to be dependent on the sample microstructure. The present results indicate that the magnetic inspection technique is able to differentiate the residual stress effects from the fatigue damage induced by cyclic loading, and therefore it is possible to detect the onset of fatigue failure in steel components via measurements of the changes in magnetic properties.--This work was sponsored by the National Science Foundation, under grant number CMS-9532056

  20. Problems in development of pressure vessel steels

    International Nuclear Information System (INIS)

    McMahon, C.Y.

    1980-01-01

    The tendency of steels to intercrystalline fracture at low stresses is the main factor, limiting fracture resistance of steels in agressive media at conventional and elevated temperatures. The reasons for the phenomenon are analyzed. In particular, the role of grain boundary segregations of non-metallic impurities is pointed out. The ways of the problem solving both at the expense of corresponding microstructure control and by means of selection of the steel chemical composition are considered

  1. On residual stresses and fatigue of laser hardened steels

    International Nuclear Information System (INIS)

    Lin, Ru.

    1992-01-01

    This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10 7 cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au)

  2. On residual stresses and fatigue of laser hardened steels

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ru.

    1992-01-01

    This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10[sup 7] cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au).

  3. Fatigue crack Behaviour in a High Strength Tool Steel

    DEFF Research Database (Denmark)

    Højerslev, Christian; Carstensen, Jesper V.; Brøndsted, Povl

    2002-01-01

    The influence of microstructure on fatigue crack initiation and crack growth of a hardened and tempered high speed steel was investigated. The evolution of fatigue cracks was followed in four point bending at room temperature. It was found that a carbide damage zone exists above a threshold load...... value of maximally 80% of the yield strength of the steel. The size of this carbide damage zone increases with increasing load amplitude, and the zone is apparently associated with crack nucleation. On fatigue crack propagation plastic deformation of the matrix occurs in a radius of approximately 4...... microns in front of the fatigue crack tip, which is comparable with the relevant mean free carbide spacing....

  4. Crack behaviour of ferritic pressure vessels steels in oxygenated high temperature water under transient loadings. Crack corrosion phase 2. Crack development and fatigue. Final report; Rissverhalten ferritischer Druckbehaelterstaehle in sauerstoffhaltigem Hochtemperaturwasser bei transienten Vorgaengen. Risskorrosion Phase 2. Rissentstehung und Ermuedung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Weissenberg, Thomas

    2014-03-15

    Using the example of the ferritic steels 22NiMoCr3-7 and 15MnNi6-3 representative for Nuclear Power Plants experimental data for the evaluation of the influence of the light water reactor (LWR) coolant environment and postulated chloride contaminations on crack development and fatigue have been determined in order to verify and extend the basis for a reliable estimation of the residual service life of reactor components. The aim of the research project was the investigation of the environmental effects at low strain rate conditions and the determination of the fatigue life under cyclic loading at uniaxial and multiaxial stress state. The quasi-static tensile tests (Constant Extension Rate Test, CERT) were performed using 3 low strain rates, each differing by about one order of magnitude (2.5.10{sup -3}, 3.1.10{sup -4} and 2.3.10{sup -5} %/s). The low cycle fatigue (LCF) experiments were conducted applying alternating tensile-compression loading with strain amplitudes of 0.3, 0.5 and 0.9 % at strain rates of 0.1 and 0.01 %/s (tests in air primarily 0.1 %/s). The cyclic notched tensile tests were carried out with a nominal axial strain in the notch root of 0.5 % at a strain rate of 0.1 %/s. The experiments in each case were performed in air, high purity water and chloride containing water at a testing temperature of 240 C, the oxygen content of the liquid medium was set to 0.4 ppm (simulated boiling water reactor coolant). In the CERT experiments chloride contents of 30, 50 and 100 ppb were applied, in the LCF tests the chloride content was 50 ppb which can be regarded as an upper realistic limit for a postulated chloride contamination of the reactor coolant. All experiments in liquid environment were preceded by a pre-autoclaving phase of at least 100 h in order to allow the formation of a stable oxide layer (magnetite). The testing material 22NiMoCr3-7 was available in form of an original reactor pressure vessel shell primarily designated for the German nuclear

  5. Thermomechanical fatigue and damage mechanisms in Sanicro 25 steel

    Czech Academy of Sciences Publication Activity Database

    Petráš, Roman; Škorík, Viktor; Polák, Jaroslav

    2016-01-01

    Roč. 650, JAN (2016), s. 52-62 ISSN 0921-5093 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : thermomechanical fatigue * Sanicro 25 steel * damage mechanism * FIB cutting * localized oxidation-cracking Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 3.094, year: 2016

  6. Fatigue behaviour of X70 steel in crude oil

    Czech Academy of Sciences Publication Activity Database

    Gajdoš, Lubomír; Šperl, Martin; Bystrianský, J.

    2015-01-01

    Roč. 49, č. 2 (2015), s. 243-246 ISSN 1580-2949 R&D Projects: GA ČR(CZ) GAP105/10/2052; GA TA ČR(CZ) TE02000162 Institutional support: RVO:68378297 Keywords : corrosion fatigue * S-N curve * X70 steel * crude oil * separated water Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.439, year: 2015 http://mit.imt.si/Revija/izvodi/mit152/gajdos.pdf

  7. Threshold Corrosion Fatigue of Welded Shipbuilding Steels.

    Science.gov (United States)

    1992-01-01

    8. J. C. Walter, E. Olbjorn, 0. Allstad and G. Elde, "Safety Against Corrosion Fatigue Offshore," Publication No. 94, Det Norske Ventas , Horik...Offshore. Publication No;. 94;, Det Norske Ventas , Horik, Norway, April 1976. 18. C. E. Jaske, D. Broek, J. E. Slater, W. E. Anderson. Corrosion Fatigue

  8. Irradiation embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Bros, J.

    2000-01-01

    From the historical decision of closing the Yankee Rowe NPP because of the uncertainties on the level of reactor pressure vessel neutron embrittlement, this paper reviews the technical-scientist bases of the degradation phenomena, and refers to the evolution of reactor pressure vessel radiation surveillance programs. (Author)

  9. Fatigue crack nucleation of type 316LN stainless steel

    International Nuclear Information System (INIS)

    Kim, Dae Whan; Kim, Woo Gon; Hong, Jun Hwa; Ryu, Woo Seog

    2000-01-01

    Low Cycle Fatigue (LCF) life decreases drastically with increasing temperature but increases with the addition of nitrogen at room and high temperatures. The effect of nitrogen on LCF life may be related to crack nucleation at high temperatures in austenitic stainless steel because the fraction of crack nucleation in LCF life is about 40%. The influence of nitrogen on the crack nucleation of LCF in type 316LN stainless steel is investigated by observations of crack population and crack depth after testing at 40% of fatigue life. Nitrogen increases the number of cycles to nucleate microcracks of 100 μm but decreases the crack population

  10. Fatigue behaviour and crack growth of ferritic steel under environmental conditions

    International Nuclear Information System (INIS)

    Herter, K.H.; Schuler, X.; Weissenberg, T.

    2012-01-01

    The assessment of fatigue and cyclic crack growth behaviour of safety relevant components is of importance for the ageing management with regard to safety and reliability. For cyclic stress evaluation different codes and standards provide fatigue analysis procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. For the fatigue design curves used as a limiting criteria the influence of different factors like e.g. environment, surface finish and temperature must be taken into consideration in an appropriate way. Fatigue tests were performed in the low cycle fatigue (LCF) und high cycle fatigue (HCF) regime with low alloy steels as well as with Nb- and Ti-stabilized German austenitic stainless steels in air and high temperature (HT) boiling water reactor environment to extend the state of knowledge of environmentally assisted fatigue (EAF) as it can occur in boiling water reactor (BWR) plants. Using the reactor pressure vessel (RPV) steel 22NiMoCr3-7 experimental data were developed to verify the influence of BWR coolant environment (high purity water as well as sulphate containing water with 90 ppb SO 4 at a test temperature of 240 C and an oxygen content of 400 ppb) on the fatigue life and to extend the basis for a reliable estimation of the remaining service life of reactor components. Corresponding experiments in air were performed to establish reference data to determine the environmental correction factor F en accounting for the environment. The experimental results are compared with international available mean data curves, the new design curves and on the basis of the environmental factor F en . Furthermore the behaviour of steel 22NiMoCr3-7 in oxygenated high temperature water under transient loading conditions was investigated with respect to crack initiation and cyclic crack growth. In this process the stress state of the specimen and the chemical composition of the high

  11. Static and Fatigue Behavior Investigation of Artificial Notched Steel Reinforcement

    Directory of Open Access Journals (Sweden)

    Yafei Ma

    2017-05-01

    Full Text Available Pitting corrosion is one of the most common forms of localized corrosion. Corrosion pit results in a stress concentration and fatigue cracks usually initiate and propagate from these corrosion pits. Aging structures may fracture when the fatigue crack reaches a critical size. This paper experimentally simulates the effects of pitting morphologies on the static and fatigue behavior of steel bars. Four artificial notch shapes are considered: radial ellipse, axial ellipse, triangle and length-variable triangle. Each shape notch includes six sizes to simulate a variety of pitting corrosion morphologies. The stress-strain curves of steel bars with different notch shape and depth are obtained based on static tensile testing, and the stress concentration coefficients for various conditions are determined. It was determined that the triangular notch has the highest stress concentration coefficient, followed by length-variable triangle, radial ellipse and axial ellipse shaped notches. Subsequently, the effects of notch depth and notch aspect ratios on the fatigue life under three stress levels are investigated by fatigue testing, and the equations for stress range-fatigue life-notch depth are obtained. Several conclusions are drawn based on the proposed study. The established relationships provide an experimental reference for evaluating the fatigue life of concrete bridges.

  12. Fatigue Life of High-Strength Steel Offshore Tubular Joints

    DEFF Research Database (Denmark)

    Petersen, Rasmus Ingomar; Agerskov, Henning; Lopez Martinez, Luis

    1996-01-01

    In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high-strength......In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high......-strength steel with a yield stress of 820-830 MPa and with high weldability and toughness properties. The test specimens of both series had the same geometry. The present report concentrates on the results obtained in the investigation on the high-strength steel tubular joints.The test specimens were fabricated...... from Ø 324-610 mm tubes, and the joints were loaded in in-plane bending. Both fatigue tests under constant amplitude loading and tests with a stochastic loading that is realistic in relation to offshore structures, are included in the investigation.A comparison between constant amplitude and variable...

  13. Stress corrosion cracking studies on ferritic low alloy pressure vessel steel - water chemistry and modelling aspects

    International Nuclear Information System (INIS)

    Tipping, P.; Ineichen, U.; Cripps, R.

    1994-01-01

    The susceptibility of low alloy ferritic pressure vessel steels (A533-B type) to stress corrosion cracking (SCC) degradation has been examined using various BWR type coolant chemistries. Fatigue pre-cracked wedge-loaded double cantilever beams and also constantly loaded 25 mm thick compact tension specimens have shown classical SCC attack. The influence of parameters such as dissolved oxygen content, water impurity level and conductivity, material chemical composition (sulphur content) and stress intensity level are discussed. The relevance of SCC as a life-limiting degradation mechanism for low alloy ferritic nuclear power plant PV steel is examined. Some parameters, thought to be relevant for modelling SCC processes in low alloy steels in simulated BWR-type coolant, are discussed. 8 refs., 1 fig., 4 tabs

  14. ESTIMATION OF IRREVERSIBLE DAMAGEABILITY AT FATIGUE OF CARBON STEEL

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2014-04-01

    Full Text Available Purpose. Damageability estimation of carbon steel in the conditions of cyclic loading. Methodology. The steel fragments of railway wheel rim and rail head served as material for research with chemical composition 0.65 % С, 0.67 % Mn, 0.3 % Si, 0.027 % P, 0.028 % S и 0.7 % C, 0.82 % Mn, 0.56 % Si, 0.025 % P, 0.029 % S accordingly. The microstructure of tested steels corresponded to the state of metal after a hot plastic deformation. The fatigue research was conducted in the conditions of symmetric bend using the proof-of-concept machine of type «Saturn-10». Full Wohler diagrams and the lines corresponding to forming of sub-and micro cracks were constructed. The distribution analysis of internal stresses in the metal under cyclic loading was carried out using the microhardness tester of PMT-3 type.Findings. On the basis of fatigue curves for high-carbon steels analysis the positions of borders dividing the areas of convertible and irreversible damages were determined. The article shows that with the growth of carbon concentration in the steel at invariability of the structural state an increase of fatigue limit is observed. At the same time the acceleration of processes, which determine transition terms from the stage of forming of submicrocracks to the microcracks occurs. The research of microhardness distribution in the metal after destruction confirmed the nature of carbon amount influence on the carbon steel characteristics. Originality. Regardless on the stages of breakdown site forming the carbon steels behavior at a fatigue is determined by the ration between the processes of strengthening and softening. At a cyclic loading the heterogeneity of internal stresses distribution decreases with the increase of distance from the destruction surface. Analysis of metal internal restructuring processes at fatigue loading made it possible to determine that at the stages prior to incubation period in the metal microvolumes the cells are already

  15. Corrosion of vessel steel during its interaction with molten corium

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Granovsky, V.S.; Lopukh, D.B.; Gusarov, V.V.; Martinov, A.P.; Martinov, V.V.; Fieg, G.; Tromm, W.; Bottomley, D.; Tuomisto, H.

    2006-01-01

    An experimental examination of the cooled vessel steel corrosion during the interaction with molten corium is presented. The experiments have been conducted on 'Rasplav-2' test facility and followed up with physico-chemical and metallographic analyses of melt samples and corium-specimen ingots. The results discussed in the first part of the paper have revealed specific corrosion mechanisms for air and inert atmosphere above the melt. Models have been proposed based on this information and approximate curves constructed for the estimation of the corrosion rate or corrosion depth of vessel steel in conditions simulated by the experiments

  16. Corrosion of vessel steel during its interaction with molten corium

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation)]. E-mail: bechta@sbor.spb.su; Khabensky, V.B. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation); Vitol, S.A. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation); Krushinov, E.V. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation); Granovsky, V.S. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation); Lopukh, D.B. [SPb Electrotechnical University (SpbGETU), Professor Popov str., b.5/3, 197376 St. Petersburg (Russian Federation); Gusarov, V.V. [Institute of Silicate Chemistry of Russian Academy of Science (ISC of RAS), Odoevsky str., b. 24/2, 199155 St. Petersburg (Russian Federation); Martinov, A.P. [SPb Electrotechnical University (SpbGETU), Professor Popov str., b.5/3, 197376 St. Petersburg (Russian Federation); Martinov, V.V. [Scientific Research Technological Institute (NITI), Sosnovy Bor of Leningrad Oblast 188540 (Russian Federation); Fieg, G. [Forshungszentrum Karlsruhe (FZK), Institut fur Neutronenphysik and Reaktortechnik, Postfach 3640, D-78021 Karlsruhe (Germany); Tromm, W. [Forshungszentrum Karlsruhe (FZK), Institut fur Neutronenphysik and Reaktortechnik, Postfach 3640, D-78021 Karlsruhe (Germany); Bottomley, D. [Europaeische Kommission, General Direktion GFS, Institut fuer Transurane (ITU), Postfach 2340, 76125 Karlsruhe (Germany); Tuomisto, H. [Fortum Engineering Ltd. 00048 FORTUM, Rajatorpantie 8, Vantaa (Finland)

    2006-07-15

    An experimental examination of the cooled vessel steel corrosion during the interaction with molten corium is presented. The experiments have been conducted on 'Rasplav-2' test facility and followed up with physico-chemical and metallographic analyses of melt samples and corium-specimen ingots. The results discussed in the first part of the paper have revealed specific corrosion mechanisms for air and inert atmosphere above the melt. Models have been proposed based on this information and approximate curves constructed for the estimation of the corrosion rate or corrosion depth of vessel steel in conditions simulated by the experiments.

  17. The Vibration Based Fatigue Damage Assessment of Steel and Steel Fiber Reinforced Concrete (SFRC Composite Girder

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2015-01-01

    Full Text Available The steel-concrete composite girder has been usually applied in the bridge and building structures, mostly consisting of concrete slab, steel girder, and shear connector. The current fatigue damage assessment for the composite girder is largely based on the strain values and concrete crack features, which is time consuming and not stable. Hence the vibration-based fatigue damage assessment has been considered in this study. In detail, a steel-steel fiber reinforced concrete (SFRC composite girder was tested. The steel fiber reinforced concrete is usually considered for dealing with the concrete cracks in engineering practice. The composite girder was 3.3m long and 0.45m high. The fatigue load and impact excitation were applied on the specimen sequentially. According to the test results, the concrete crack development and global stiffness degradation during the fatigue test were relatively slow due to the favourable performance of SFRC in tension. But on the other hand, the vibration features varied significantly during the fatigue damage development. Generally, it confirmed the feasibility of executing fatigue damage assessment of composite bridge based on vibration method.

  18. Radiation embrittlement of Spanish nuclear reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Bros, J.; Ballesteros, A.; Lopez, A.

    1993-01-01

    Commercial pressurized water reactor (PWR) and boiling water reactor (BWR) nuclear power plants contain a series of pressure vessel steel surveillance capsules as the principal means of monitoring radiation effects on the pressure vessel. Changes in fracture toughness are more severe in surveillance capsules than in reactor vessel materials because of their proximity of the reactor core. Therefore, it is possible to predict changes in fracture toughness of the reactor vessel materials. This paper describes the status of the reactor vessel surveillance program relating to Spanish nuclear power plants. To date, twelve capsules have been removed and analyzed from seven of the nine Spanish reactors in operation. The results obtained from the analysis of these capsules are compared with the predictions of the Nuclear Regulatory Commission (NRC) Regulatory Guide 1.99, Rev. 2, by means of measured and expected increase of the nil-ductility transition reference temperature (RT NDT ). The comparison is made considering the different variables normally included in the studies of radiation response of reactor pressure vessel materials, such as copper content of steel, level of neutron fluence above 1 MeV, base metal or weld metal, and so forth. The surveillance data have been used for determining the adjusted reference temperatures and upper shelf energies at any time. The results have shown that the seven pressure vessels are in excellent condition to continue operating with safety against brittle fracture beyond the design life, without the need to recuperate the degraded properties of the materials by annealing of the vessel

  19. Variability of mechanical properties of nuclear pressure vessel steels

    International Nuclear Information System (INIS)

    Petrequin, P.; Soulat, P.

    1980-01-01

    Causes of variability of mechanical properties nuclear pressure vessel steels are reviewed and discussed. The effects of product shape and size, processing history and heat treatment are investigated. Some quantitative informations are given on the scatter of mechanical properties of typical pressure vessel components. The necessity of using recommended or standardized properties for comparing mechanical properties before and after irradiation in pin pointed. (orig.) [de

  20. Fatigue design of steel and composite structures Eurocode 3 : design of steel structures, part 1-9 fatigue ; Eurocode 4 : design of composite steel and concrete structures

    CERN Document Server

    Nussbaumer, Alain; Davaine, Laurence

    2012-01-01

    This volume addresses the specific subject of fatigue, a subject not familiar to many engineers, but still relevant for proper and good design of numerous steel structures. It explains all issues related to the subject: Basis of fatigue design, reliability and various verification formats, determination of stresses and stress ranges, fatigue strength, application range and limitations. It contains detailed examples of applications of the concepts, computation methods and verifications.

  1. Cyclic deformation and fatigue behaviors of Hadfield manganese steel

    Energy Technology Data Exchange (ETDEWEB)

    Kang, J. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, F.C., E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Long, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, B. [School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2014-01-03

    The cyclic deformation characteristics and fatigue behaviors of Hadfield manganese steel have been investigated by means of its ability to memorize strain and stress history. Detailed studies were performed on the strain-controlled low cycle fatigue (LCF) and stress-controlled high cycle fatigue (HCF). Initial cyclic hardening to saturation or peak stress followed by softening to fracture occurred in LCF. Internal stress made the dominant contribution to the fatigue crack propagation until failure. Effective stress evolution revealed the existence of C–Mn clusters with short-range ordering in Hadfield manganese steel and demonstrated that the interaction between C atoms in the C–Mn cluster and dislocation was essential for its cyclic hardening. The developing/developed dislocation cells and stacking faults were the main cyclic deformation microstructures on the fractured sample surface in LCF and HCF, which manifested that fatigue failure behavior of Hadfield manganese steel was induced by plastic deformation during strain-controlled or stress-controlled testing.

  2. Fatigue and creep-fatigue in sodium of 316 1 stainless steel

    International Nuclear Information System (INIS)

    Ardellier, A.

    1982-01-01

    Equipment and results obtained on type 316 L stainless stee1 at 450 0 C and 600 0 C with low-cycle fatique and creep fatigue tests are described. Comparison with runs in air on type 316 L stainless steel shows a better low-cycle fatigue behavior in a sodium environment. This beneficial effect can be attributed to the low oxygen content which limits the surface oxidazation

  3. Crude Oil Corrosion Fatigue of L485MB Pipeline Steel

    Czech Academy of Sciences Publication Activity Database

    Gajdoš, Lubomír; Šperl, Martin; Bystrianský, J.

    2015-01-01

    Roč. 137, č. 5 (2015), 051401 ISSN 0094-9930 R&D Projects: GA TA ČR(CZ) TE02000162 Institutional support: RVO:68378297 Keywords : corrosion fatigue * crude oil * pipeline steel * S–N curve * separated water Subject RIV: JI - Composite Materials Impact factor: 0.476, year: 2015 http://pressurevesseltech.asmedigitalcollection.asme.org/article.aspx?articleID=2107675

  4. Testing of a steel containment vessel model

    International Nuclear Information System (INIS)

    Luk, V.K.; Hessheimer, M.F.; Matsumoto, T.; Komine, K.; Costello, J.F.

    1997-01-01

    A mixed-scale containment vessel model, with 1:10 in containment geometry and 1:4 in shell thickness, was fabricated to represent an improved, boiling water reactor (BWR) Mark II containment vessel. A contact structure, installed over the model and separated at a nominally uniform distance from it, provided a simplified representation of a reactor shield building in the actual plant. This paper describes the pretest preparations and the conduct of the high pressure test of the model performed on December 11-12, 1996. 4 refs., 2 figs

  5. Fatigue Life Analysis and Prediction of 316L Stainless Steel Under Low Cycle Fatigue Loading

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Hyeong; Myung, NohJun; Choi, Nak-Sam [Hanyang Univ., Seoul (Korea, Republic of)

    2016-12-15

    In this study, a strain-controlled fatigue test of widely-used 316L stainless steel with excellent corrosion resistance and mechanical properties was conducted, in order to assess its fatigue life. Low cycle fatigue behaviors were analyzed at room temperature, as a function of the strain amplitude and strain ratio. The material was hardened during the initial few cycles, and then was softened during the long post period, until failure occurred. The fatigue life decreased with increasing strain amplitude. Masing behavior in the hysteresis loop was shown under the low strain amplitude, whereas the high strain amplitude caused non-Masing behavior and reduced the mean stress. Low cycle fatigue life prediction based on the cyclic plastic energy dissipation theory, considering Masing and non-Masing effects, showed a good correlation with the experimental results.

  6. Low Cycle Fatigue of Steel in Strain Controled Cyclic Bending

    Directory of Open Access Journals (Sweden)

    Kulesa Anna

    2016-03-01

    Full Text Available The paper presents a comparison of the fatigue life curves based on test of 15Mo3 steel under cyclic, pendulum bending and tension-compression. These studies were analyzed in terms of a large and small number of cycles where strain amplitude is dependent on the fatigue life. It has been shown that commonly used Manson-Coffin-Basquin model cannot be used for tests under cyclic bending due to the impossibility of separating elastic and plastic strains. For this purpose, some well-known models of Langer and Kandil and one new model of authors, where strain amplitude is dependent on the number of cycles, were proposed. Comparing the results of bending with tension-compression it was shown that for smaller strain amplitudes the fatigue life for both test methods were similar, for higher strain amplitudes fatigue life for bending tests was greater than for tension-compression.

  7. Creep-fatigue interactions in an austenitic stainless steel

    International Nuclear Information System (INIS)

    Majumdar, S.; Maiya, P.S.

    1978-01-01

    A phenomenological model of the interaction between creep and fatigue in Type 304 stainless steel at elevated temperatures is presented. The model is based on a crack-growth equation and an equation governing cavity growth, expressed in terms of current plastic strain and plastic strain rate. Failure is assumed to occur when a proposed interaction equation is satisfied. Various parameters of the equations can be obtained by correlation with continuously cycling fatigue and monotonic creep-rupture test data, without the use of any hold-time fatigue tests. Effects of various wave shapes such as tensile, compressive, and symmetrical hold on the low-cycle fatigue life can be computed by integrating the damage-rate equations along the appropriate loading path. Microstructural evidence in support of the proposed model is also discussed

  8. Studies on fatigue life enhancement of pre-fatigued spring steel specimens using laser shock peening

    International Nuclear Information System (INIS)

    Ganesh, P.; Sundar, R.; Kumar, H.; Kaul, R.; Ranganathan, K.; Hedaoo, P.; Raghavendra, G.; Anand Kumar, S.; Tiwari, P.; Nagpure, D.C.; Bindra, K.S.; Kukreja, L.M.; Oak, S.M.

    2014-01-01

    Highlights: • Laser peening significantly extended fatigue life of pre-fatigued spring steel. • Increase in fatigue life of laser peened specimens was more than 15 times. • Black PVC tape is an effective coating for laser peening of ground surfaces. • Repeat peening repaired local surface melted regions on laser peened surface. • Technique is effective for life extension of in-service automobile parts. - Abstract: SAE 9260 spring steel specimens after enduring 50% of their mean fatigue life were subjected to laser shock peening using an in-house developed 2.5 J/7 ns pulsed Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser for studying their fatigue life enhancement. In the investigated range of process parameters, laser shock peening resulted in the extension of fatigue life of these partly fatigue damaged specimens by more than 15 times. Contributing factors for the enhanced fatigue life of laser peened specimens are: about 400 μm thick compressed surface layer with magnitude of surface stress in the range of −600 to −700 MPa, about 20% increase in surface hardness and unaltered surface finish. For laser peening of ground steel surface, an adhesive-backed black polyvinyl chloride (PVC) tape has been found to be a superior sacrificial coating than conventionally used black paint. The effect of repeated laser peening treatment was studied to repair locally surface melted regions and the treatment has been found to be effective in re-establishing desired compressive stress pattern on the erstwhile tensile-stressed surface

  9. Corrosion fatigue in nitrocarburized quenched and tempered steels

    Science.gov (United States)

    Khani, M. Karim; Dengel, D.

    1996-05-01

    In order to investigate the fatigue strength and fracture mechanism of salt bath nitrocarburized steels, specimens of the steels SAE 4135 and SAE 4140, in a quenched and tempered state, and additionally in a salt bath nitrocarburized and oxidizing cooled state as well as in a polished (after the oxidizing cooling) and renewed oxidized state, were subjected to comparative rotating bending fatigue tests in inert oil and 5 pct NaCl solution. In addition, some of the quenched and tempered specimens of SAE 4135 material were provided with an approximately 50-μm-thick electroless Ni-P layer, in order to compare corrosion fatigue behavior between the Ni-P layer and the nitride layers. Long-life corrosion fatigue tests of SAE 4135 material were carried out under small stresses in the long-life range up to 108 cycles with a test frequency of 100 Hz. Fatigue tests of SAE 4140 material were carried out in the range of finite life (low-cycle range) with a test frequency of 13 Hz. The results show that the 5 pct NaCl environment drastically reduced fatigue life, but nitrocarburizing plus oxidation treatment was found to improve the corrosion fatigue life over that of untreated and Ni-P coated specimens. The beneficial effect of nitrocarburizing followed by oxidation treatment on cor-rosion fatigue life results from the protection rendered by the compound layer by means of a well-sealed oxide layer, whereby the pores present in the compound layer fill up with oxides. The role of inclusions in initiating fatigue cracks was investigated. It was found that under corrosion fatigue conditions, the fatigue cracks started at cavities along the interfaces of MnS inclusions and matrix in the case of quenched and tempered specimens. The nitrocarburized specimens, however, showed a superposition of pitting corrosion and corrosion fatigue in which pores and nonmetallic inclusions in the compound layer play a predominant role concerning the formation of pits in the substrate.

  10. Fracture toughness of irradiated and recovered vessel steels

    International Nuclear Information System (INIS)

    Perosanz, F.; Lapena, J.

    1998-01-01

    This paper presents the fracture toughness measurements carried out on three vessel steels in an irradiated condition and after a post-irradiation recovery treatment. A statistical approach and the fracture parameters corresponding to two theoretical models of the fracture tests are used for evaluating toughness. Test results show that the neutron fluence gradually transforms the fracture behaviour of the vessel steels from ductile to brittle and seriously reduces their fracture toughness. The effectiveness of the recovery treatment, as evaluated from the toughness measurements, is confirmed, although the efficiency is not the same for the steels and depends on the evaluation parameter except in the case of almost complete recovery. The recovery effect increases with the received neutron fluence if the toughness values after treatment are compared with those in the irradiated condition rather than those in the as received condition. (orig.)

  11. Microstructural evolution in reactor pressure vessel steel under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Katsumi; Fukuya, Koji [Institute of Nuclear Safety System Inc., Seika, Kyoto (Japan)

    2000-09-01

    Understanding microstructural changes in reactor pressure vessel steels is important in order to evaluate radiation-induced embrittlement, one of the major aging phenomena affecting the extension of plant life. In this study, actual surveillance test specimens and samples of rector vessel low-alloy steel (A533B steel) irradiated in a research reactor were examined using state-of-the-art techniques to clarify the neutron flux effect on the microstructural changes. These techniques included small angle neutron scattering and atom probes. Microstructural changes which are considered to be the main factors affecting embrittlement, including the production of copper-rich precipitates and the segregation of impurity elements, were confirmed by the results of the study. In addition, the mechanical properties were predicted based on the obtained quantitative data such as the diameters of precipitates. Consequently, the hardening due to irradiation was almost simulated. (author)

  12. Low cycle fatigue properties of CLAM steel at 823 K

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xue [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Huang, Lixin [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Yan, Wei; Wang, Wei [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sha, Wei [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, Belfast BT9 5AG (United Kingdom); Shan, Yiyin, E-mail: yyshan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2014-09-08

    China Low Activation Martensitic (CLAM) steel is considered to be the main candidate material for the first wall components of future fusion reactors in China. In this paper, the low cycle fatigue (LCF) behavior of CLAM steel is studied under fully reversed tension–compression loading at 823 K in air. Total strain amplitude was controlled from 0.14% to 1.8% with a constant strain rate of 2.4×10{sup −3} s{sup −1}. The corresponding plastic strain amplitude ranged from 0.023% to 1.613%. The CLAM steel displayed continuous softening to failure at 823 K. The relationship between strain, stress and fatigue life was obtained using the parameters obtained from fatigue tests. The LCF properties of CLAM steel at 823 K followed Coffin–Manson relationship. Furthermore, irregular serration was observed on the stress–strain hysteresis loops of CLAM steel tested with the total strain amplitude of 0.45–1.8%, which was attributed to the dynamic strain aging (DSA) effect. During continuous cyclic deformation, the microstructure and precipitate distribution of CLAM steel changed gradually. Many tempered martensitic laths were decomposed into subgrains, and the size and number of M{sub 23}C{sub 6} carbide and MX carbonitride precipitates decreased with the increase of total strain amplitude. The response cyclic stress promoted the recovery of martensitic lath, while the thermal activation mainly played an important role on the growth of precipitates in CLAM steel at 823 K. In order to have a better understanding of high-temperature LCF behavior, the potential mechanisms controlling stress–strain response, DSA phenomenon and microstructure changes have also been evaluated.

  13. Microstructure and embrittlement of VVER 440 reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Hennion, A.

    1999-03-01

    27 VVER 440 pressurised water reactors operate in former Soviet Union and in Eastern Europe. The pressure vessel, is made of Cr-Mo-V steel. It contains a circumferential arc weld in front of the nuclear core. This weld undergoes a high neutron flux and contains large amounts of copper and phosphorus, elements well known for their embrittlement potency under irradiation. The embrittlement kinetic of the steel is accelerated, reducing the lifetime of the reactor. In order to get informations on the microstructure and mechanical properties of these steels, base metals, HAZ, and weld metals have been characterized. The high amount of phosphorus in weld metals promotes the reverse temper embrittlement that occurs during post-weld heat treatment. The radiation damage structure has been identified by small angle neutron scattering, atomic probe, and transmission electron microscopy. Nanometer-sized clusters of solute atoms, rich in copper with almost the same characteristics as in western pressure vessels steels, and an evolution of the size distribution of vanadium carbides, which are present on dislocation structure, are observed. These defects disappear during post-irradiation tempering. As in western steels, the embrittlement is due to both hardening and reduction of interphase cohesion. The radiation damage specificity of VVER steels arises from their high amount of phosphorus and from their significant density of fine vanadium carbides. (author)

  14. Interfacial fatigue stress in PVD TiN coated tool steels under rolling contact fatigue conditions

    NARCIS (Netherlands)

    Carvalho, N.J.M.; Huis in 't Veld, A.J.; Hosson, J.T. de

    1998-01-01

    Titanium-nitrogen (TiN) films were Physical Vapour Deposited (PVD) on tool steel substrates with different hardness and surface roughness, in a Bai 640R unit using a triode ion plating (e-gun) with a high plasma density. The coated substrates were submitted to a rolling contact fatigue test

  15. Interfacial fatigue stress in PVD TiN coated tool steels under rolling contact fatigue conditions

    NARCIS (Netherlands)

    Carvalho, N.J.M.; Huis in ’t Veld, A.J.; Hosson, J.Th. De

    1998-01-01

    Titanium–nitrogen (TiN) films were Physical Vapour Deposited (PVD) on tool steel substrates with different hardness and surface roughness, in a Bai 640R unit using a triode ion plating (e-gun) with a high plasma density. The coated substrates were submitted to a rolling contact fatigue test

  16. Fatigue behavior of welded austenitic stainless steel in different environments

    Directory of Open Access Journals (Sweden)

    D.S. Yawas

    2014-01-01

    Full Text Available The fatigue behavior of welded austenitic stainless steel in 0.5 M hydrochloric acid and wet steam corrosive media has been investigated. The immersion time in the corrosive media was 30 days to simulate the effect on stainless steel structures/equipment in offshore and food processing applications and thereafter annealing heat treatment was carried out on the samples. The findings from the fatigue tests show that seawater specimens have a lower fatigue stress of 0.5 × 10−5 N/mm2 for the heat treated sample and 0.1 × 10−5 N/mm2 for the unheat-treated sample compared to the corresponding hydrochloric acid and steam samples. The post-welding heat treatment was found to increase the mechanical properties of the austenitic stainless steel especially tensile strength but it reduces the transformation and thermal stresses of the samples. These findings were further corroborated by the microstructural examination of the stainless steel specimen.

  17. Low cycle fatigue: high cycle fatigue damage accumulation in a 304L austenitic stainless steel

    International Nuclear Information System (INIS)

    Lehericy, Y.

    2007-05-01

    The aim of this study was to evaluate the consequences of a Low Cycle Fatigue pre-damage on the subsequent fatigue limit of a 304L stainless steel. The effects of hardening and severe roughness (grinding) have also been investigated. In a first set of tests, the evolution of the surface damage induced by the different LCF pre-cycling was characterized. This has permitted to identify mechanisms and kinetics of damage in the plastic domain for different surface conditions. Then, pre-damaged samples were tested in the High Cycle Fatigue domain in order to establish the fatigue limits associated with each level of pre-damage. Results evidence that, in the case of polished samples, an important number of cycles is required to initiate surface cracks ant then to affect the fatigue limit of the material but, in the case of ground samples, a few number of cycles is sufficient to initiate cracks and to critically decrease the fatigue limit. The fatigue limit of pre-damaged samples can be estimated using the stress intensity factor threshold. Moreover, this detrimental effect of severe surface conditions is enhanced when fatigue tests are performed under a positive mean stress (author)

  18. Low Temperature Irradiation Embrittlement of Reactor Pressure Vessel Steels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-01

    The embrittlement trend curve development project for HFIR reactor pressure vessel (RPV) steels was carried out with three major tasks. Which are (1) data collection to match that used in HFIR steel embrittlement trend published in 1994 Journal Nuclear Material by Remec et. al, (2) new embrittlement data of A212B steel that are not included in earlier HFIR RPV trend curve, and (3) the adjustment of nil-ductility-transition temperature (NDTT) shift data with the consideration of the irradiation temperature effect. An updated HFIR RPV steel embrittlement trend curve was developed, as described below. NDTT( C) = 23.85 log(x) + 203.3 log (x) + 434.7, with 2- uncertainty of 34.6 C, where parameter x is referred to total dpa. The developed update HFIR RPV embrittlement trend curve has higher embrittlement rate compared to that of the trend curve developed in 1994.

  19. Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints

    Science.gov (United States)

    Lakshminarayanan, A. K.; Shanmugam, K.; Balasubramanian, V.

    2009-10-01

    The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

  20. Progress in the Research of Fatigue of Weathering Steel after Corrosion

    Science.gov (United States)

    Jianyu, Liang; Jian, Yao; Youwu, Xu

    2017-12-01

    Weathering steel has a good corrosion resistance in the atmosphere, and the application of weathering steel in civil structure also reduces the cost of painting and maintenance. It is also possible for the bare weathering steel to bear the fatigue load with a rust layer. This paper summarizes the fatigue researches after corrosion of weathering steel, including the shape of specimens, failure modes of fatigue and the conclusions obtained through experimental investigations. It is also introduced the fatigue model of weathering steel after corrosion, which can be useful for the engineering application or further researches.

  1. Statistical analysis of elevated-temperature, strain-controlled fatigue data on Type 304 stainless steel

    International Nuclear Information System (INIS)

    Diercks, D.R.; Raske, D.T.

    1976-01-01

    The available elevated-temperature, strain-controlled, uniaxial fatigue data on Type 304 stainless steel (435 data points) are summarized, and variables that influence cyclic life are divided into first- and second-order categories. The first-order variables, which include strain range, strain rate, temperature, and tensile hold time, were used in a multivariable regression analysis to describe the observed variation in fatigue life. Goodness of fit with respect to these variables as well as the appropriateness of the transformations employed are discussed. Confidence intervals are estimated, and a comparison with the ASME Boiler and Pressure Vessel Code Case 1592 creep-fatigue design curve is made for a particular set of conditions. The second-order variables include the laboratories at which the data were generated, the different heats from which the test specimens were fabricated, and the heat treatments that preceded testing. These variables were statistically analyzed to determine their effect on fatigue life. The results are discussed, and the heats and heat treatments that are most resistant to fatigue damage under these loading and environmental conditions are identified

  2. Heavy Section Steel Technology Program. Part II. Intermediate vessel testing

    International Nuclear Information System (INIS)

    Whitman, G.D.

    1975-01-01

    The testing of the intermediate pressure vessels is a major activity under the Heavy Section Steel Technology Program. A primary objective of these tests is to develop or verify methods of fracture prediction, through the testing of selected structures and materials, in order that a valid basis can be established for evaluating the serviceability and safety of light-water reactor pressure vessels. These vessel tests were planned with sufficiently specific objectives that substantial quantitative weight could be given to the results. Each set of testing conditions was chosen so as to provide specific data by which analytical methods of predicting flaw growth, and in some cases crack arrest, could be evaluated. Every practical effort was made to assure that results would be relevant to some aspect of real reactor pressure vessel performance through careful control of material properties, selection of test temperatures, and design of prepared flaws. 5 references

  3. Fatigue and creep-fatigue strength of 304 steel under biaxial strain conditions

    International Nuclear Information System (INIS)

    Asayama, Tai; Aoto, Kazumi; Wada, Yusaku

    1990-01-01

    A series of fatigue and creep-fatigue tests were conducted with 304 stainless steel at 550degC under a variety of biaxial strain conditions. Fatigue life under nonproportional loading conditions showed a significant life reduction compared with that of proportional loading, and this life reduction was reasonably estimated by taking into account the strain paths along which the strain history is imposed. Furthermore, a marked life reduction was shown to occur under nonproportional loading by imposing a strain hold period at a peak tensile strain. This life reduction was evaluated by the linear damage rule. It was shown to be possible to estimate the fatigue damage and the creep damage under nonproportional loading by a linear damage rule by estimating a stress relaxation behavior by Mises-type equivalent stress or Huddleston-type equivalent stress. (author)

  4. Behavior of Steel Branch Connections during Fatigue Loading

    Directory of Open Access Journals (Sweden)

    Sládek A.

    2017-09-01

    Full Text Available Fatigue behavior of the branch connection made of low-alloyed steel with yield stress of 355 MPa during low-cycle bending test is investigated in the article. Numerical prediction of the stress and strain distribution are described and experimentally verified by fatigue test of the branch connection sample. Experimental verification is based on low-cycle bending testing of the steel pipes welded by manual metal arc process and loaded by external force in the appropriate distance. Stresses and displacement of the samples induced by bending moment were measured by unidirectional strain gauges and displacement transducers. Samples were loaded in different testing levels according to required stress for 2.106 cycles. Increase of the stress value was applied until the crack formation and growth was observed. Results showed a high agreement of numerical and experimental results of stress and displacement.

  5. Magnetic and electrical properties of ITER vacuum vessel steels

    International Nuclear Information System (INIS)

    Mergia, K.; Apostolopoulos, G.; Gjoka, M.; Niarchos, D.

    2007-01-01

    Full text of publication follows: Ferritic steel AISI 430 is a candidate material for the lTER vacuum vessel which will be used to limit the ripple in the toroidal magnetic field. The magnetic and electrical properties and their temperature dependence in the temperature range 300 - 900 K of AISI 430 ferritic stainless steels are presented. The temperature variation of the coercive field, remanence and saturation magnetization as well as electrical resistivity and the effect of annealing on these properties is discussed. (authors)

  6. Neutron irradiation effects in pressure vessel steels and weldments

    Energy Technology Data Exchange (ETDEWEB)

    Ianko, L [International Atomic Energy Agency, Vienna (Austria). Div. of Nuclear Power; Davies, L M

    1994-12-31

    This paper deals with the effects of neutron irradiation on the steel and welds used for the pressure vessels which house the reactor cores in light water reactors: irradiation effects on mechanical properties and the shift in ductile-brittle transition temperature, importance of the knowledge of the neutron fluence and of the monitoring and surveillance programmes; empirical and mechanistic modelling of irradiation effects and the necessity of data extension to new operational limits; consequences on the manufacturing and structural design of materials and structures; mitigation of irradiation effects by annealing; international activities and programmes in the field of neutron irradiation effects on PV steels and welds. 37 refs., 22 figs.

  7. Fatigue crack growth in austenitic stainless steel piping

    International Nuclear Information System (INIS)

    Bethmont, M.; Cheissoux, J.L.; Lebey, J.

    1981-04-01

    The study presented in this paper is being carried out with a view to substantiating the calculations of the fatigue crack growth in pipes made of 316 L stainless steel. The results obtained may be applied to P.W.R. primary piping. It is divided into two parts. First, fatigue tests (cyclic pressure) are carried out under hot and cold conditions with straight pipes machined with notches of various dimensions. The crack propagation and the fatigue crack growth rate are measured here. Second, calculations are made in order to interpret experimental results. From elastic calculations the stress intensity factor is assessed to predict the crack growth rate. The results obtained until now and presented in this paper relate to longitudinal notches

  8. Fatigue fracture of steel after mechanical and ultrasonic strengthening

    International Nuclear Information System (INIS)

    Stotskij, I.M.

    1978-01-01

    Fatigue fracture surfaces of samples after mechanical and ultrasonic strengthening have been studied metallographically and by electron fractography. Studied was the 40Kh steel hardened from 850 deg and then tempered at 180 deg or at 550 deg C. The ultrasound power was 25 kWt, the frequency was 20 kHz, the sample rotation velocity was 39.5 m/min. Mechanical and ultrasonic treatment was found to cause structural changes (formation of a white layer) and deformation of the material under the layer. The fatigue cracks were extending beyond the white layer; their propagation involved generation and coalescence of microcracks on account of segregation of carbides. It is concluded that mechanical and ultrasonic treatment should be used for increasing the fatigue strength of low and average strength materials rather than hardened or low-tempered ones

  9. Microstructural heterogeneities and fatigue anisotropy of forged steels

    Energy Technology Data Exchange (ETDEWEB)

    Pessard, Etienne, E-mail: etienne.pessard@angers.ensam.fr [LAMPA, Arts et Metiers ParisTech Angers, 2 Bd du Ronceray, 49035 Angers Cedex 01 (France); Morel, Franck [LAMPA, Arts et Metiers ParisTech Angers, 2 Bd du Ronceray, 49035 Angers Cedex 01 (France); Verdu, Catherine [MATEIS, INSA-Lyon, Universite de Lyon, 25 Av Jean Capelle, 69621 Villeurbanne Cedex (France); Flaceliere, Laurent; Baudry, Gilles [CREAS - ASCOMETAL, BP 70045, 57301 Hagondange (France)

    2011-11-25

    Highlights: {yields} Tomography result: fibering is composed of non-metallic inclusions bands. {yields} Elongated inclusions decreases the: ductility, fracture toughness and fatigue limit. {yields} Cracks initiate from both inclusion clusters and from the bainitic matrix. {yields} The classical self-heating method does not predict the effect of the inclusions. - Abstract: In this study, various experimental methods are employed to determine the anisotropic fatigue behavior of a 25MnCrSiVB6 forged steel (Metasco MC). This material has a bainitic microstructure and contains many elongated non-metallic inclusions in the rolled direction, which are grouped into clusters. Specimens with different orientations relative to the rolling direction have been extracted from a hot rolled bar and the ability of certain experimental techniques to capture the fatigue anisotropy has been tested. Results obtained from monotonic tensile tests and Charpy impact tests show that the material has isotropic fracture strength and anisotropic ductility. The influence of the 'inclusion clusters' is clearly demonstrated via observation of the fracture surfaces. Concerning the fatigue behavior, results from a classical staircase experimental procedure are compared to results from self-heating fatigue tests. For specimens orientated at 0{sup o} relative to the rolled direction, microcrack initiation is controlled by the material matrix and the prediction of the fatigue strength with the self-heating method has been observed to be correct. For specimens orientated at 45{sup o} and 90{sup o}, the elongated manganese sulfide inclusion clusters are the origin of crack initiation and the fatigue strength drops significantly. For this case, it appears that the self-heating method has difficulty predicting the fatigue behavior.

  10. Microstructural heterogeneities and fatigue anisotropy of forged steels

    International Nuclear Information System (INIS)

    Pessard, Etienne; Morel, Franck; Verdu, Catherine; Flaceliere, Laurent; Baudry, Gilles

    2011-01-01

    Highlights: → Tomography result: fibering is composed of non-metallic inclusions bands. → Elongated inclusions decreases the: ductility, fracture toughness and fatigue limit. → Cracks initiate from both inclusion clusters and from the bainitic matrix. → The classical self-heating method does not predict the effect of the inclusions. - Abstract: In this study, various experimental methods are employed to determine the anisotropic fatigue behavior of a 25MnCrSiVB6 forged steel (Metasco MC). This material has a bainitic microstructure and contains many elongated non-metallic inclusions in the rolled direction, which are grouped into clusters. Specimens with different orientations relative to the rolling direction have been extracted from a hot rolled bar and the ability of certain experimental techniques to capture the fatigue anisotropy has been tested. Results obtained from monotonic tensile tests and Charpy impact tests show that the material has isotropic fracture strength and anisotropic ductility. The influence of the 'inclusion clusters' is clearly demonstrated via observation of the fracture surfaces. Concerning the fatigue behavior, results from a classical staircase experimental procedure are compared to results from self-heating fatigue tests. For specimens orientated at 0 o relative to the rolled direction, microcrack initiation is controlled by the material matrix and the prediction of the fatigue strength with the self-heating method has been observed to be correct. For specimens orientated at 45 o and 90 o , the elongated manganese sulfide inclusion clusters are the origin of crack initiation and the fatigue strength drops significantly. For this case, it appears that the self-heating method has difficulty predicting the fatigue behavior.

  11. A Review on Strengthening Steel Beams Using FRP under Fatigue

    Directory of Open Access Journals (Sweden)

    Mohamed Kamruzzaman

    2014-01-01

    Full Text Available In recent decades, the application of fibre-reinforced polymer (FRP composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems.

  12. A review on strengthening steel beams using FRP under fatigue.

    Science.gov (United States)

    Kamruzzaman, Mohamed; Jumaat, Mohd Zamin; Sulong, N H Ramli; Islam, A B M Saiful

    2014-01-01

    In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE) simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP) is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems.

  13. A Review on Strengthening Steel Beams Using FRP under Fatigue

    Science.gov (United States)

    Jumaat, Mohd Zamin; Ramli Sulong, N. H.

    2014-01-01

    In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE) simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP) is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems. PMID:25243221

  14. Fatigue Life Estimation of Medium-Carbon Steel with Different Surface Roughness

    Directory of Open Access Journals (Sweden)

    Changyou Li

    2017-03-01

    Full Text Available Medium-carbon steel is commonly used for the rail, wire ropes, tire cord, cold heading, forging steels, cold finished steel bars, machinable steel and so on. Its fatigue behavior analysis and fatigue life estimation play an important role in the machinery industry. In this paper, the estimation of fatigue life of medium-carbon steel with different surface roughness using established S-N and P-S-N curves is presented. To estimate the fatigue life, the effect of the average surface roughness on the fatigue life of medium-carbon steel has been investigated using 75 fatigue tests in three groups with average surface roughness (Ra: 0.4 μm, 0.8 μm, and 1.6 μm, respectively. S-N curves and P-S-N curves have been established based on the fatigue tests. The fatigue life of medium-carbon steel is then estimated based on Tanaka-Mura crack initiation life model, the crack propagation life model using Paris law, and material constants of the S-N curves. Six more fatigue tests have been conducted to validate the presented fatigue life estimation formulation. The experimental results have shown that the presented model could estimate well the mean fatigue life of medium-carbon steel with different surface roughness.

  15. Radiation embrittlement of WWER 440 pressure vessel steel and of some improved steels by western producers

    International Nuclear Information System (INIS)

    Koutsky, J.; Vacek, M.; Stoces, B.; Pav, T.; Otruba, J.; Novosad, P.; Brumovsky, M.

    1982-01-01

    The resistance was studied of Cr-Mo-V type steel 15Kh2MFA to radiation embrittlement at an irradiation temperature of around 288 degC. Studied was the steel used for the manufacture of the pressure vessel of the Paks nuclear reactor in Hungary. The obtained results of radiation embrittlement and hardening of steel 15Kh2MFA were compared with similar values of Mn-Ni-Mo type steels A 533-B and A 508 manufactured by leading western manufacturers within the international research programme coordinated by the IAEA. It was found that the resistance of steel 15Kh2MFA to radiation embrittlement is comparable with steels A 533-B and A 508 by western manufacturers. (author)

  16. Pressure vessel steels: influence of chemical composition on irradiation sensitivity

    International Nuclear Information System (INIS)

    Ghoniem, M.M.; Hammad, F.H.

    1998-01-01

    Neutron irradiation of the steels used in the construction of the nuclear reactor pressure vessels can lead to the embrittlement of these materials, increasing the ductile-to-brittle transition temperature and decreasing the fracture energy, which can limit the plant life. The knowledge of irradiation embrittlement and the means for minimizing such degradation is therefore important in the field of assuring the safety of the nuclear power plants. Irradiation embrittlement is quite a complex process. It involves many variables. The most important of these are irradiation temperature, neutron fluence (neutron dose), neutron flux (neutron dose rate), and chemical composition of the irradiated material. This paper is concerned with the effect of chemical composition, the role of residual and alloying elements in the irradiation embrittlement of nuclear reactor pressure vessel steels in light water reactors. It presents a critical review for the published work in this field through the last 25 years

  17. Environmentally-Assisted Cracking of Low-Alloy Reactor Pressure Vessel Steels under Boiling Water Reactor Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P.; Ritter, S

    2002-02-01

    The present report summarizes the experimental work performed by PSI on the environmentally-assisted cracking (EAC) of low-alloy steels (LAS) in the frame of the RIKORR-project during the period from January 2000 to August 2001. Within this project, the EAC crack growth behaviour of different low-alloy reactor pressure vessel (RPV) steels, weld filler and weld heat-affected zone materials is investigated under simulated transient and steady-state BWR/NWC power operation conditions. The EAC crack growth behaviour of different low-alloy RPV steels was characterized by slow rising load (SRL) / low-frequency corrosion fatigue (LFCF) and constant load tests with pre-cracked fracture mechanics specimens in oxygenated high-temperature water at temperatures of either 288, 250, 200 or 150 C. These tests revealed the following important interim results: Under low-flow and highly oxidizing (ECP >= 100 mV SHE) conditions, the ASME XI 'wet' reference fatigue crack growth curve could be significantly exceeded by cyclic fatigue loading at low frequencies (<0.001 Hz), at high and low load-ratios R, and by ripple loading near to DKth fatigue thresholds. The BWR VIP 60 SCC disposition lines may be significantly or slightly exceeded (even in steels with a low sulphur content) in the case of small load fluctuations at high load ratios (ripple loading) or at intermediate temperatures (200 -250 C) in RPV materials, which show a distinct susceptibility to dynamic strain ageing (DSA). (author)

  18. Bayesian Model on Fatigue Crack Growth Rate of Type 304 Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sanhae; Yoon, Jae Young; Hwang, Il Soon [Nuclear Materials Laboratory, Seoul National University, Seoul (Korea, Republic of)

    2015-10-15

    The fatigue crack growth rate curve is typically estimated by deterministic methods in accordance with the ASME Boiler and Pressure Vessel Code Sec. XI. The reliability of nuclear materials must also consider the environmental effect. This can be overcome by probabilistic methods that estimate the degradation of materials. In this study, fatigue tests were carried out on Type 304 stainless steel (STS 304) to obtain a fatigue crack growth rate curve and Paris' law constants. Tests were conducted on a constant load and a constant delta K, respectively. The unknown constants of Paris' law were updated probabilistically by Bayesian inference and the method can be used for the probabilistic structural integrity assessment of other nuclear materials. In this paper, Paris' law constants including C and m for Type 304 stainless steel were determined by probabilistic approach with Bayesian Inference. The Bayesian update process is limited in accuracy, because this method should assume initial data distribution. If we select an appropriate distribution, this updating method is powerful enough to get data results considering the environment and materials. Until now, remaining lives of NPPs are estimated by deterministic methods using a priori model to finally assess structural integrity. Bayesian approach can utilize in-service inspection data derived from aged properties.

  19. Effects of neutron irradiation and fatigue on ductility of stainless steel DIN 1.4948

    International Nuclear Information System (INIS)

    Vries, M.I. de; Schaaf, B. van der; Staal, H.U.; Elen, J.D.

    1978-10-01

    Test specimens of stainless steel DIN 1.4948, which is similar to AISI type 304, have been irradiated at 723 K and 823 K up to fluences of 1.10 23 neutrons (n).m -2 and 5.10 24 n.m -2 (E > 0.1 MeV). These are representative conditions for the SNR-300 reactor vessel and inner components after 16 years of operation. High temperature (723 K to 1023 K) tensile tests at strain rates (depsilon/dt) from 10 -7 s -1 to 10 s -1 show a considerable decrease of tensile ductility. The extent depends on helium content, test temperature and strain rate. The atomic helium fractions of 3.10 -7 and 7.10 -6 result from the reactions of thermal neutrons with the 14 ppm boron, present in the steel. Helium embrittlement sets in at strain rates below 1 s -1 to 10 s -1 (the range of interest for Bethe-Tait accident analyses). A minimum total elongation value of 6% is shown at 923 K. The post-irradiation fatigue life is reduced by up to about 50% due to intergranular cracking. The combination of irradiation and fatigue causes a decrease of ductility after a smaller number of prior fatigue cycles than in the case of unirradiated material. (Auth.)

  20. Effects of neutron irradiation and fatigue on ductility of stainless steel DIN-1-4948

    International Nuclear Information System (INIS)

    de Vries, M.I.; van der Schaaf, B.; Staal, H.U.; Elen, J.D.

    1978-01-01

    Test specimens of stainless steel DIN 1.4948, which is similar to AISI Type 304, have been irradiated at 723 and 823 K up to fluences of 1*10$sup 23$ neutrons (n)*m$sup -2$ and 5*10$sup 24$ n*m$sup -2$ (E>0.1 MeV). These are representative conditions for the reactor vessel and inner components of the liquid metal fast breeder reactor SNR-300 after 16 years of operation. High-temperature (723 to 1023 K) tension tests at strain rates ($epsilon$) from 10$sup -7$ to 10 s$sup -1$ show a considerable decrease of tensile ductility. The extent depends on helium content, test temperature, and strain rate. The atomic helium fractions of 3*10$sup -7$ and 7*10$sup -6$ result from the reactions of thermal neutrons with the 14 ppm boron present in the steel. Helium embrittlement sets in at strain rates below 1 to 10 s$sup -1$ (the range of interest for Bethe-Tait accident analyses). A minimum total elongation value of 6 percent is shown at 923 K. The postirradiation fatigue life is reduced by up to about 50 percent due to intergranular cracking. The combination of irradiation and fatigue causes a decrease of ductility after a smaller number of prior fatigue cycles than in the case of unirradiated material. 8 refs

  1. Bayesian Model on Fatigue Crack Growth Rate of Type 304 Stainless Steel

    International Nuclear Information System (INIS)

    Choi, Sanhae; Yoon, Jae Young; Hwang, Il Soon

    2015-01-01

    The fatigue crack growth rate curve is typically estimated by deterministic methods in accordance with the ASME Boiler and Pressure Vessel Code Sec. XI. The reliability of nuclear materials must also consider the environmental effect. This can be overcome by probabilistic methods that estimate the degradation of materials. In this study, fatigue tests were carried out on Type 304 stainless steel (STS 304) to obtain a fatigue crack growth rate curve and Paris' law constants. Tests were conducted on a constant load and a constant delta K, respectively. The unknown constants of Paris' law were updated probabilistically by Bayesian inference and the method can be used for the probabilistic structural integrity assessment of other nuclear materials. In this paper, Paris' law constants including C and m for Type 304 stainless steel were determined by probabilistic approach with Bayesian Inference. The Bayesian update process is limited in accuracy, because this method should assume initial data distribution. If we select an appropriate distribution, this updating method is powerful enough to get data results considering the environment and materials. Until now, remaining lives of NPPs are estimated by deterministic methods using a priori model to finally assess structural integrity. Bayesian approach can utilize in-service inspection data derived from aged properties

  2. Studies of fragileness in steels of vessels of BWR reactors

    International Nuclear Information System (INIS)

    Robles, E.F.; Balcazar, M.; Alpizar, A.M.; Calderon, B.E.

    2003-01-01

    The structural materials with those that are manufactured the pressure vessels of the BWR reactors, suffer degradation in its mechanical properties mainly to the damage taken place by the fast neutrons (E > 1 MeV) coming from the reactor core. Its are experimentally studied those mechanisms of neutron damage in this material type, by means of the irradiation of steel vessel in experimental reactors to age them quickly. Alternatively it is simulated the neutron damage by means of irradiation of steel with heavy ions. In this work those are shown first results of the damage induced by irradiation from a similar steel to the vessel of a BWR reactor. The irradiation was carried out with fast neutrons (E > 1 MeV, fluence of 1.45 x 10 18 n/cm 2 ) in the TRIGA MARK lll reactor and separately with Ni +3 ions in a Tandetrom accelerator, E = 4.8 MeV and range of the ionic flow of 0.1 to 53 iones/A 2 . (Author)

  3. Low cycle fatigue studies on a type 304 stainless steel

    International Nuclear Information System (INIS)

    Bhanu Sankara Rao, K.; Valsan, M.; Sandhya, R.; Ray, S.K.; Rodriguez, P.

    The effects of temperature and strain rate on the low cycle fatigue behaviour were investigated for an AISI 304 stainless steel under total axial strain control mode at 823 and 923 K. The fatigue life was strongly dependent on cyclic deformation rate for this material at these temperatures, decreasing markedly with decreasing strain rate. The cyclic stress-strain response recorded in the form of hysterisis loops exhibited serrations at low strain rates at 823 and 923 K. Cyclic stress-strain response at 823 K has shown an increase in saturation stress and decrease in plastic strain range whereas there is an increase in plastic strain range without marked variation in saturation stress level at 923 K with decreasing strain rate. It has been observed that there are three simultaneous effects namely environment, creep and cyclic strain ageing which contribute to the observed degradation in fatigue life at low strain rates. At 823 K, where the creep damage as well as environmental damage is relatively small, the fatigue life is considered mainly to be affected by dynamic strain ageing effect which depends on strain rate. At 923 K, on the other hand, the strain rate dependence of fatigue life is considered to be determined by the combination of creep and environmental effects. Deformation and fracture studies have also confirmed that the wedge type crack propagation is accelerated by oxidation effect. (author)

  4. Creep-fatigue damage in austenitic stainless steels

    International Nuclear Information System (INIS)

    Rezgui, Brahim.

    1980-06-01

    This is a study of hold time effects on the low cycle fatigue (L.C.F.) properties of 316L austenitic stainless steel at 600 0 C in air. Results obtained for different plastic strain levels indicate that a tension hold time at peak strain lead to a reduction in fatigue life. The importance of this effect depend on the length of hold period, and also on the strain amplitude. No saturation had been observed. Metallographic and microstructural analysis of failed specimens indicates mechanisms by which failure is produced. For continuous cycling the fractures occurs by the initiation and the propagation of a trans-granular crack. Creep damage in the bulk of material is formed during periods of tensile stress relaxation; it causes a change in the failure mode which became intergranular. It is the interaction between this creep-damage and fatigue cracks which is partly responsable for the reduction in the fatigue life. Predictions based upon linear cumulative damage method indicate that virgin material properties may be irrelevant in creep-fatigue interactions [fr

  5. Corrosion of steel tendons used in prestressed concrete pressure vessels

    International Nuclear Information System (INIS)

    Griess, J.C.; Naus, D.J.

    The purpose of this investigation was to determine the corrosion behavior of a high strength steel (ASTM A416-74 grade 270), typical of those used as tensioning tendons in prestressed concrete pressure vessels, in several corrosive environments and to demonstrate the protection afforded by coating the steel with either of two commercial petroleum-base greases or Portland Cement grout. In addition, the few reported incidents of prestressing steel failures in concrete pressure vessels used for containment of nuclear reactors are reviewed. The susceptibility of the steel to stress corrosion cracking and hydrogen embrittlement and its general corrosion rate were determined in several salt solutions. Wires coated with the greases and grout were soaked for long periods in the same solutions and changes in their mechanical properties were subsequently determined. All three coatings appeared to give essentially complete protection but small flaws in the grease coatings were detrimental; flaws or cracks less than 1 mm wide in the grout were without effect

  6. Fatigue and fracture mechanics in pressure vessels and piping. PVP-Volume 304

    International Nuclear Information System (INIS)

    Mehta, H.S.; Wilkowski, G.; Takezono, S.; Bloom, J.; Yoon, K.; Aoki, S.; Rahman, S.; Nakamura, T.; Brust, F.; Yoshimura, S.

    1995-01-01

    Fracture mechanics and fatigue evaluations are an important part of the structural integrity analyses to assure safe operation of pressure vessels and piping components during their service life. The paper presented in this volume illustrate the application of fatigue and fracture mechanics techniques to assess the structural integrity of a wide variety of Pressure Vessels and Piping components. The papers are organized in six sections: (1) fatigue and fracture--vessels; (2) fatigue and fracture--piping; (3) fatigue and fracture--material property evaluations; (4) constraint effects in fracture mechanics; (5) probabilistic fracture mechanics analyses; and (6) user's experience with failure assessment diagrams. Separate abstracts were prepared for most of the papers in this book

  7. Interim fatigue design curves for carbon, low-alloy, and austenitic stainless steels in LWR environments

    International Nuclear Information System (INIS)

    Majumdar, S.; Chopra, O.K.; Shack, W.J.

    1993-01-01

    Both temperature and oxygen affect fatigue life; at the very low dissolved-oxygen levels in PWRs and BWRs with hydrogen water chemistry, environmental effects on fatigue life are modest at all temperatures (T) and strain rates. Between 0.1 and 0.2 ppM, the effect of dissolved-oxygen increases rapidly. In oxygenated environments, fatigue life depends strongly on strain rate and T. A fracture mechanics model is developed for predicting fatigue lives, and interim environmentally assisted cracking (EAC)-adjusted fatigue curves are proposed for carbon steels, low-alloy steels, and austenitic stainless steels

  8. Fatigue cracks in Eurofer 97 steel: Part II. Comparison of small and long fatigue crack growth

    Czech Academy of Sciences Publication Activity Database

    Kruml, Tomáš; Hutař, Pavel; Náhlík, Luboš; Seitl, Stanislav; Polák, Jaroslav

    2011-01-01

    Roč. 412, 1 (2011), s. 7-12 ISSN 0022-3115 R&D Projects: GA ČR GA106/09/1954; GA ČR GA101/09/0867 Institutional research plan: CEZ:AV0Z20410507 Keywords : ferritic-martensitic steel * long crack growth * small crack growth * crack closure Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.052, year: 2011

  9. Thermal fatigue strength estimation of 2.25Cr-1Mo steel under creep-fatigue interaction

    International Nuclear Information System (INIS)

    Kuwahara, Kazuo; Nitta, Akihito; Kitamura, Takayuki

    1980-01-01

    A 2-1/4Cr-1Mo steel is one of principal materials for high temperature equipments in nuclear and thermal power plants. The authors experimentally analyzed the high temperature fatigue strength and creep strength of a 2-1/4 Cr-1Mo steel main steam pipe which had been used in a thermal plant for operation up to 130,000 hours, and pointed out that the strain-range vs. life curves crossed each other due to the difference of temperature-strain phase in thermal fatigue. This suggests that it is difficult to estimate thermal fatigue life of steel materials having been subjected to different temperature-strain phase on the basis of isothermal low-cycle fatigue life at the upper limit temperature of thermal fatigue, and that it is urgently required to establish an appropriate method of evaluating thermal fatigue life. The authors attempted to prove that the strain range partitioning method used for the evaluation of thermal fatigue life in SUS 304 steels is applicable to this 2-1/4Cr-1Mo steel. Consequently, it was found that the thermal fatigue life could be estimated within a factor of 2.5 by the application of this method. (author)

  10. Properties of high temperature low cycle fatigue in austenitic stainless steel

    International Nuclear Information System (INIS)

    Kim, D. H.; Han, C. H.; Ryu, W. S.

    2002-01-01

    Tensile and fatigue tests were conducted at R. T. and 300 .deg. C for type 304 and 316 stainless steel. Tensile strength and elongation decreased and fatigue life increased with temperature for both type 304 and 316 stainless steel. Dislocation structures were mixed with cell and planar at R. T. and 300 .deg. C for both type 304 and 316 stainless steel. Strain induced martensite of type 316 stainless steel was less than that of type 304 stainless steel and decreased with temperature. It is considered that strain induced martensite is an important factor to increase fatigue life at 300 .deg. C

  11. Artificial neural networks and the effects of loading conditions on fatigue life of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Pleune, T.T.

    1996-11-01

    The ASME Boiler and Pressure Vessel Code contains rules for the construction of nuclear power plant components. Figure 1-90 of Appendix I to Section III of the 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. Recent test data indicate significant decreases in the fatigue lives of carbon and low-alloy steels in LWR environments when five conditions are satisfied simultaneously. When applied strain range, temperature, dissolved oxygen in the water, and sulfur content of the steel are above a minimum threshold level, and the loading strain rate is below a threshold value, environmentally assisted fatigue occurs. For this study, a data base of 1036 fatigue tests was used to train an artificial neural network (ANN). Once the optimal ANN was designed, ANN were trained and used to predict fatigue life for specified sets of loading and environmental conditions. By finding patterns and trends in the data, the ANN can find the fatigue lifetime for any set of conditions. Artificial neural networks show great potential for predicting environmentally assisted corrosion. Their main benefits are that the fit of the data is based purely on data and not on preconceptions and that the network can interpolate effects by learning trends and patterns when data are not available

  12. Fatigue in Welded High-Strength Steel Plate Elements under Stochastic Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1999-01-01

    The present project is a part of an investigation on fatigue in offshore structures in high-strength steel. The fatigue life of plate elements with welded attachments is studied. The material used has a yield stress of ~ 810-840 MPa, and high weldability and toughness properties. Fatigue test...... series with constant amplitude loading and with various types of stochastic loading have been carried through on test specimens in high-strength steel, and - for a comparison - on test specimens in conventional offshore structural steel with a yield stress of ~ 400-410 MPa.A comparison between constant...... amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those...

  13. Monitoring of Fatigue Degradation in Austenitic Stainless Steels

    International Nuclear Information System (INIS)

    Kalkhof, D.; Niffenegger, M.; Leber, H.J.

    2004-01-01

    During cyclic loading of austenitic stainless steel, it was observed that microstructural changes occurred; these affect both the mechanical and physical properties of the material. For certain steels, a strain-induced martensite phase transformation was seen. The investigations showed that, for the given material and loading conditions, the volume fraction of martensite depends on the cycle number, temperature and initial material state. It was also found that the martensite content continuously increased with the cycle number. Therefore, the volume fraction of martensite was used as an indication of fatigue usage. It was noted that the temperature dependence of the martensite formation could be described by a Boltzmann function, and that the martensite content decreased with increasing temperature. Two different heats of the austenitic stainless steel X6CrNiTi18-10 (AISI 321, DIN 1.4541) were investigated. It was found that the martensite formation rate was much higher for the cold-worked than for the solution-annealed material. All applied techniques - neutron diffraction and advanced magnetic methods - were successful in detecting the presence of martensite in the differently fatigued specimens. (author)

  14. Some aspects of thermal fatigue in stainless steel

    International Nuclear Information System (INIS)

    Iorio, A.F.; Crespi, J.C.

    1987-01-01

    This paper is concerned with the analysis of failures in a moderator circuit branch piping of the ATUCHA-I pressurized heavy water reactor (PHWR), made of austenitic steel to DIN 1.4550 specification (similar to AISI 347). These failures are considered to result from a thermal fatigue processes induced by fluctuations in a zone where stratified temperature layers occurred -the fluctuations being associated with variations in the heavy water flow. The first section evaluates the possibility of cracking due to thermal fatigue phenomena and concludes that under service conditions a crack may be initiated and growth through 7 mm of the wall thickness of the pipe. Laboratory thermal fatigue tests that simulated the thermomechanical conditions for such a component, showed that the number of cycles required to initiate a thermal fatigue crack in a notched modified standard fatigue specimen was about 10 3 . This value may be used to give a conservative prediction of the number of thermal cycles for crack initiation in actual station piping, including those who suffered a cold plug condition which is produced in some emergency shut-down and valve testing situations. It was also demonstrated that beyond a crack depth of 7 mm stress corrosion cracking has the main process in further crack propagation. The relevance of this prediction has been confirmed by microfractographic observations, since the brittle nature of the fracture surfaces under service conditions appears very different from the transgranular ductile striations found in both thermal and mechanical fatigue test specimens as a result of environmental effects. (Author)

  15. High Temperature Creep-Fatigue-Oxidation Interactions in 9% Cr Martensitic Steels

    International Nuclear Information System (INIS)

    Fournier, B.; Sauzay, M.; Pineau, A.

    2007-01-01

    Full text of publication follows: Martensitic steels of the 9-12%Cr family are widely used in the energy industry and were selected as candidate materials for structural components of future fusion reactors [1,2]. Typical in-service conditions require operating temperatures between 673 and 873 K, which means that the creep behaviour of these steels is of primary interest. In addition, some components are anticipated to operate in a pulsed mode, leading to complex time-dependencies of temperature, stress and strain in materials. Therefore, in design procedures, fatigue and creep-fatigue data are required. Furthermore, to meet the need for very long inservice lifetime of components (with very long hold times ∼ one month) reliable cyclic lifetime models are necessary, since complete tests with such long holding periods cannot, of course, be carried out in laboratory. To make these extrapolations safer and more reliable a precise understanding of the damage and interaction mechanisms is required. Fatigue, creep-fatigue and relaxation-fatigue tests were carried out at high temperature (823 K), under three different atmospheres (air, vacuum and He+impurities) and for a large panel of applied fatigue and creep strain. Holding periods are found to decrease the fatigue lifetime. Surprisingly enough compressive holding periods are more deleterious than tensile ones in air. Observations were carried out on fracture surfaces, specimen surfaces and cross sections. No creep cavity is visible, whatever the holding period duration, but a major influence of oxidation is highlighted. Oxidation is all the more predominant for low applied strains. Tests carried out under vacuum and helium show that the formation of a thick oxide layer can lead to a fatigue lifetime 4 times shorter. Crack propagation is mainly transgranular for all applied strains. Both damage observations and a theoretical study of oxide layers fracture mechanisms allow qualitative explanations for recorded fatigue

  16. 46 CFR 42.09-30 - Additional survey requirements for steel-hull vessels.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Additional survey requirements for steel-hull vessels...-30 Additional survey requirements for steel-hull vessels. (a) In addition to the requirements in § 42...) When the vessel is in drydock, the hull plating, etc., shall be examined. (c) The holds, 'tween decks...

  17. Creep of A508/533 Pressure Vessel Steel

    Energy Technology Data Exchange (ETDEWEB)

    Richard Wright

    2014-08-01

    ABSTRACT Evaluation of potential Reactor Pressure Vessel (RPV) steels has been carried out as part of the pre-conceptual Very High Temperature Reactor (VHTR) design studies. These design studies have generally focused on American Society of Mechanical Engineers (ASME) Code status of the steels, temperature limits, and allowable stresses. Initially, three candidate materials were identified by this process: conventional light water reactor (LWR) RPV steels A508 and A533, 2¼Cr-1Mo in the annealed condition, and Grade 91 steel. The low strength of 2¼Cr-1Mo at elevated temperature has eliminated this steel from serious consideration as the VHTR RPV candidate material. Discussions with the very few vendors that can potentially produce large forgings for nuclear pressure vessels indicate a strong preference for conventional LWR steels. This preference is based in part on extensive experience with forging these steels for nuclear components. It is also based on the inability to cast large ingots of the Grade 91 steel due to segregation during ingot solidification, thus restricting the possible mass of forging components and increasing the amount of welding required for completion of the RPV. Grade 91 steel is also prone to weld cracking and must be post-weld heat treated to ensure adequate high-temperature strength. There are also questions about the ability to produce, and very importantly, verify the through thickness properties of thick sections of Grade 91 material. The availability of large components, ease of fabrication, and nuclear service experience with the A508 and A533 steels strongly favor their use in the RPV for the VHTR. Lowering the gas outlet temperature for the VHTR to 750°C from 950 to 1000°C, proposed in early concept studies, further strengthens the justification for this material selection. This steel is allowed in the ASME Boiler and Pressure Vessel Code for nuclear service up to 371°C (700°F); certain excursions above that temperature are

  18. Strain-rate dependent fatigue behavior of 316LN stainless steel in high-temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jibo [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, Xinqiang, E-mail: xqwu@imr.ac.cn [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En-Hou; Ke, Wei; Wang, Xiang [CAS Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Sun, Haitao [Nuclear and Radiation Safety Center, SEPA, Beijing 100082 (China)

    2017-06-15

    Low cycle fatigue behavior of forged 316LN stainless steel was investigated in high-temperature water. It was found that the fatigue life of 316LN stainless steel decreased with decreasing strain rate from 0.4 to 0.004 %s{sup −1} in 300 °C water. The stress amplitude increased with decreasing strain rate during fatigue tests, which was a typical characteristic of dynamic strain aging. The fatigue cracks mainly initiated at pits and slip bands. The interactive effect between dynamic strain aging and electrochemical factors on fatigue crack initiation is discussed. - Highlights: •The fatigue lives of 316LN stainless steel decrease with decreasing strain rate. •Fatigue cracks mainly initiated at pits and persistent slip bands. •Dynamic strain aging promoted fatigue cracks initiation in high-temperature water.

  19. High cycle fatigue of austenitic stainless steels under random loading

    International Nuclear Information System (INIS)

    Gauthier, J.P.; Petrequin, P.

    1987-08-01

    To investigate reactor components, load control random fatigue tests were performed at 300 0 C and 550 0 C, on specimens from austenitic stainless steels plates in the transverse orientation. Random solicitations are produced on closed loop servo-hydraulic machines by a mini computer which generates random load sequence by the use of reduced Markovian matrix. The method has the advantage of taking into account the mean load for each cycle. The solicitations generated are those of a stationary gaussian process. Fatigue tests have been mainly performed in the endurance region of fatigue curve, with scattering determination using stair case method. Experimental results have been analysed aiming at determining design curves for components calculations, depending on irregularity factor and temperature. Analysis in term of mean square root fatigue limit calculation, shows that random loading gives more damage than constant amplitude loading. Damage calculations following Miner rule have been made using the probability density function for the case where the irregularity factor is nearest to 100 %. The Miner rule is too conservative for our results. A method using design curves including random loading effects with irregularity factor as an indexing parameter is proposed

  20. Mechanism of Fatigue Crack Growth of Bridge Steel Structures

    Directory of Open Access Journals (Sweden)

    Zhu H.

    2016-12-01

    Full Text Available This study was carried out on the background of Sutong Bridge project based on fracture mechanics, aiming at analyzing the growth mechanism of fatigue cracks of a bridge under the load of vehicles. Stress intensity factor (SIF can be calculated by various methods. Three steel plates with different kinds of cracks were taken as the samples in this study. With the combination of finite element analysis software ABAQUS and the J integral method, SIF values of the samples were calculated. After that, the extended finite element method in the simulation of fatigue crack growth was introduced, and the simulation of crack growth paths under different external loads was analyzed. At last, we took a partial model from the Sutong Bridge and supposed its two dangerous parts already had fine cracks; then simulative vehicle load was added onto the U-rib to predict crack growth paths using the extended finite element method.

  1. Thermal fatigue behaviour for a 316 L type steel

    Science.gov (United States)

    Fissolo, A.; Marini, B.; Nais, G.; Wident, P.

    1996-10-01

    This paper deals with initiation and growth of cracks produced by thermal fatigue loadings on 316 L steel, which is a reference material for the first wall of the next fusion reactor ITER. Two types of facilities have been built. As for true components, thermal cycles have been repeatedly applied on the surface of the specimen. The first is mainly concerned with initiation, which is detected with a light microscope. The second allows one to determine the propagation of a single crack. Crack initiation is analyzed using the French RCC-MR code procedure, and the strain-controlled isothermal fatigue curves. To predict crack growth, a model previously proposed by Haigh and Skelton is applied. This is based on determination of effective stress intensity factors, which takes into account both plastic strain and crack closure phenomena. It is shown that estimations obtained with such methodologies are in good agreement with experimental data.

  2. Thermal fatigue behaviour for a 316 L type steel

    International Nuclear Information System (INIS)

    Fissolo, A.; Marini, B.; Nais, G.; Wident, P.

    1996-01-01

    This paper deals with initiation and growth of cracks produced by thermal fatigue loadings on 316 L steel, which is a reference material for the first wall of the next fusion reactor ITER. Two types of facilities have been built. As for true components, thermal cycles have been repeatedly applied on the surface of the specimen. The first is mainly concerned with initiation, which is detected with a light microscope. The second allows one to determine the propagation of a single crack. Crack initiation is analyzed using the French RCC-MR code procedure, and the strain-controlled isothermal fatigue curves. To predict crack growth, a model previously proposed by Haigh and Skelton is applied. This is based on determination of effective stress intensity factors, which takes into account both plastic strain and crack closure phenomena. It is shown that estimations obtained with such methodologies are in good agreement with experimental data. (orig.)

  3. Some aspects of thermomechanical fatigue of AISI 304L stainless steel: Part I. creep- fatigue damage

    Science.gov (United States)

    Zauter, R.; Christ, H. J.; Mughrabi, H.

    1994-02-01

    Thermomechanical fatigue (TMF) tests on the austenitic stainless steel AISI 304L have been conducted under “true≓ plastic-strain control in vacuum. This report considers the damage oc-curring during TMF loading. It is shown how the temperature interval and the phasing (in-phase, out-of-phase) determine the mechanical response and the lifetime of the specimens. If creep-fatigue interaction takes place during in-phase cycling, the damage occurs inside the ma-terial, leading to intergranular cracks which reduce the lifetime considerably. Out-of-phase cy-cling inhibits creep-induced damage, and no lifetime reduction occurs, even if the material is exposed periodically to temperatures in the creep regime. A formula is proposed which allows prediction of the failure mode, depending on whether creep-fatigue damage occurs or not. At a given strain rate, the formula is able to estimate the temperature of transition between pure fatigue and creep-fatigue damage.

  4. Nuclear reactors sited deep underground in steel containment vessels

    Energy Technology Data Exchange (ETDEWEB)

    Bourque, Robert [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

    2006-07-01

    Although nuclear power plants are certainly very safe, they are not perceived as safe by the general populace. Also, there are concerns about overland transport of spent fuel rods and other irradiated components. It is hereby proposed that the nuclear components of nuclear power plants be placed in deep underground steel vessels with secondary coolant fed from them to turbines at or near the surface. All irradiated components, including spent fuel, would remain in the chamber indefinitely. This general concept was suggested by the late Edward Teller, generated some activity 20-25 years ago and appears to be recently reviving in interest. Previous work dealt with issues of geologic stability of underground, possibly reinforced, caverns. This paper presents another approach that makes siting independent of geology by placing the reactor components in a robust steel vessel capable of resisting full overburden pressure as well as pressures resulting from accident scenarios. Structural analysis of the two vessel concepts and approximate estimated costs are presented. This work clears the way for the extensive discussions required to evaluate the advantages of this concept. (author)

  5. High cycle fatigue of Type 422 stainless steel

    International Nuclear Information System (INIS)

    Soo, P.; Chow, J.G.Y.; Sabatini, R.L.

    1978-01-01

    High cycle fatigue testing has been carried out on Type 422 stainless steel to determine the performance of cyclically stressed disks and blades in the main and auxiliary HTGR helium circulators. Tests were performed at 316, 482, and 538 0 C (600, 900, and 1000 0 F) in air for the fully reversible and mean load conditions. Goodman's analysis is shown to be valid in predicting failure at 316 0 C (600 0 F), marginally valid at 482 0 C (900 0 F), and probably invalid at 538 0 C (1000 0 F). Metallographic analyses were conducted to characterize the nature of failure for the temperatures and loading conditions investigated

  6. Study of cumulative fatigue damage on an austenitic steel

    International Nuclear Information System (INIS)

    Baudry, G.; Amzallag, C.; Bernard, J.L.

    1984-01-01

    The validity of Palmgren-Miner rule is verified for working life between about 500 and 1,000,000 cycles for two damages: one corresponding to complete rupture of smooth test piece and the other corresponding to initiation of a fatigue crack in a high stress area. Material studied is a stainless steel Z3CND17-12 (AISI 316) used in nuclear industry. Validity of the rule is better verified in the case of small cracks than for a smooth sample. (15 references are given) [fr

  7. Modeling of the mechanical behavior of austenitic stainless steels under pure fatigue and fatigue relaxation loadings

    International Nuclear Information System (INIS)

    Hajjaji-Rachdi, Fatima

    2015-01-01

    Austenitic stainless steels are potential candidates for structural components of sodium-cooled fast neutron reactors. Many of these components will be subjected to cyclic loadings including long hold times (1 month) under creep or relaxation at high temperature. These hold times are unattainable experimentally. The aim of the present study is to propose mechanical models which take into account the involved mechanisms and their interactions during such complex loadings. First, an experimental study of the pure fatigue and fatigue-relaxation behavior of 316L(N) at 500 C has been carried out with very long hold times (10 h and 50 h) compared with the ones studied in literature. Tensile tests at 600 C with different applied strain rates have been undertaken in order to study the dynamic strain ageing phenomenon. Before focusing on more complex loadings, the mean field homogenization approach has been used to predict the mechanical behavior of different FCC metals and alloys under low cycle fatigue at room temperature. Both Hill-Hutchinson and Kroener models have been used. Next, a physically-based model based on dislocation densities has been developed and its parameters measured. The model allows predictions in a qualitative agreement with experimental data for tensile loadings. Finally, this model has been enriched to take into account visco-plasticity, dislocation climb and interaction between dislocations and solute atoms, which are influent during creep-fatigue or fatigue relaxation at high temperature. The proposed model uses three adjustable parameters only and allows rather accurate prediction of the behavior of 316L(N) steel under tensile loading and relaxation. (author) [fr

  8. Study on the effect of prior fatigue and creep-fatigue damage on the fatigue and creep characteristics of 316 FR stainless steel. 2nd report. The effect of prior creep-fatigue damage on the creep and fatigue characteristics

    International Nuclear Information System (INIS)

    Yamauchi, Masafumi; Chuman, Yasuharu; Otani, Tomomi; Takahashi, Yukio

    2001-01-01

    The effect of prior creep-fatigue damage on the creep and the fatigue characteristics was studied to investigate the creep-fatigue life evaluation procedure of 316FR stainless steel. Creep and fatigue tests were conducted at 550degC by using the specimen exposed to prior creep-fatigue cycles at the same temperature and interrupted at 1/4 Nf, 1/2 Nf and 3/4 Nf cycle. The creep and fatigue strength of the pre-damaged material showed monotonic reduction with the prior creep-fatigue damage compared with the virgin material. The creep ductility also showed monotonic reduction with the prior creep-fatigue damage. These results were evaluated by the stress-based Time Fraction Rule and the strain-based Ductility Exhaustion Method. The result showed that the application of the Ductility Exhaustion Method to the creep-fatigue damage evaluation is more promising than the Time Fraction Rule. (author)

  9. Creep-fatigue life prediction method using Diercks equation for Cr-Mo steel

    International Nuclear Information System (INIS)

    Sonoya, Keiji; Nonaka, Isamu; Kitagawa, Masaki

    1990-01-01

    For dealing with the situation that creep-fatigue life properties of materials do not exist, a development of the simple method to predict creep-fatigue life properties is necessary. A method to predict the creep-fatigue life properties of Cr-Mo steels is proposed on the basis of D. Diercks equation which correlates the creep-fatigue lifes of SUS 304 steels under various temperatures, strain ranges, strain rates and hold times. The accuracy of the proposed method was compared with that of the existing methods. The following results were obtained. (1) Fatigue strength and creep rupture strength of Cr-Mo steel are different from those of SUS 304 steel. Therefore in order to apply Diercks equation to creep-fatigue prediction for Cr-Mo steel, the difference of fatigue strength was found to be corrected by fatigue life ratio of both steels and the difference of creep rupture strength was found to be corrected by the equivalent temperature corresponding to equal strength of both steels. (2) Creep-fatigue life can be predicted by the modified Diercks equation within a factor of 2 which is nearly as precise as the accuracy of strain range partitioning method. Required test and analysis procedure of this method are not so complicated as strain range partitioning method. (author)

  10. Fatigue crack propagation behavior of stainless steel welds

    Science.gov (United States)

    Kusko, Chad S.

    The fatigue crack propagation behavior of austenitic and duplex stainless steel base and weld metals has been investigated using various fatigue crack growth test procedures, ferrite measurement techniques, light optical microscopy, stereomicroscopy, scanning electron microscopy, and optical profilometry. The compliance offset method has been incorporated to measure crack closure during testing in order to determine a stress ratio at which such closure is overcome. Based on this method, an empirically determined stress ratio of 0.60 has been shown to be very successful in overcoming crack closure for all da/dN for gas metal arc and laser welds. This empirically-determined stress ratio of 0.60 has been applied to testing of stainless steel base metal and weld metal to understand the influence of microstructure. Regarding the base metal investigation, for 316L and AL6XN base metals, grain size and grain plus twin size have been shown to influence resulting crack growth behavior. The cyclic plastic zone size model has been applied to accurately model crack growth behavior for austenitic stainless steels when the average grain plus twin size is considered. Additionally, the effect of the tortuous crack paths observed for the larger grain size base metals can be explained by a literature model for crack deflection. Constant Delta K testing has been used to characterize the crack growth behavior across various regions of the gas metal arc and laser welds at the empirically determined stress ratio of 0.60. Despite an extensive range of stainless steel weld metal FN and delta-ferrite morphologies, neither delta-ferrite morphology significantly influence the room temperature crack growth behavior. However, variations in weld metal da/dN can be explained by local surface roughness resulting from large columnar grains and tortuous crack paths in the weld metal.

  11. Structural health monitoring in end-of-life prediction for steel bridges subjected to fatigue cracking

    NARCIS (Netherlands)

    Attema, T.; Courage, W.M.G.; Maljaars, J.; Meerveld, H. van; Paulissen, J.H.; Pijpers, R.J.M.; Slobbe, A.T.

    2015-01-01

    This paper presents a monitoring and modelling methodology to assess the current and future conditions of steel bridges subjected to fatigue cracking. Steel bridges are subjected to fatigue cracking as a result of fluctuating stresses caused by the crossing of heavy vehicles. Specifically for

  12. Preliminary results of steel containment vessel model test

    International Nuclear Information System (INIS)

    Matsumoto, T.; Komine, K.; Arai, S.

    1997-01-01

    A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11-12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented

  13. Effect of residual stress on fatigue crack propagation at 200 C in a welded joint austenitic stainless steel - ferritic steel

    International Nuclear Information System (INIS)

    Zahouane, A.I.; Gauthier, J.P.; Petrequin, P.

    1988-01-01

    Fatigue resistance of heterogeneous welded joints between austenitic stainless steels and ferritic steels is evaluated for reactor components and more particularly effect of residual stress on fatigue crack propagation in a heterogeneous welded joint. Residual stress is measured by the hole method in which a hole is drilled through the center of a strain gage glued the surface of the materials. In the non uniform stress field a transmissibility function is used for residual stress calculation. High compression residual stress in the ferritic metal near the interface ferritic steel/weld slow down fatigue crack propagation. 5 tabs., 15 figs., 19 refs [fr

  14. Fatigue Assessment of High Strength Steel Welded Joints Under Bending Loading

    International Nuclear Information System (INIS)

    Lee, Myeong-Woo; Kim, Yun-Jae; Park, Jun-Hyub

    2014-01-01

    In this study, a fatigue assessment method for vehicle suspension systems having welded geometries was established under a bending loading condition. For the fatigue life estimation of the actual product s welded joints made of different steels, bending fatigue tests were performed on welded specimens with a simplified shape for obtaining the moment-fatigue-life plot. Further, geometry modeling of the simplified welded specimens was conducted. Results of finite element analysis were used to obtain the stress-fatigue-life plot. The analysis results were also used to calculate the stress concentration factors for notch-factor-based fatigue life estimation. The test results were compared with results of the general notch-factor-based fatigue life estimation for improving fatigue assessment. As a result, it was concluded that both the welded fatigue tests and the notch-factor-based fatigue life estimation are necessary for accurate fatigue assessment

  15. Fatigue of carbon and low-alloy steels in LWR environments

    International Nuclear Information System (INIS)

    Chopra, O.K.; Michaud, W.F.; Shack, W.J.

    1994-01-01

    Fatigue tests have been conducted on A106-Gr B carbon steel and A533-Gr B low-alloy steel to evaluate the effects of an oxygenated-water environment on the fatigue life of these steels. For both steels, environmental effects are modest in PWR water at all strain rates. Fatigue data in oxygenated water confirm the strong dependence of fatigue life on dissolved oxygen (DO) and strain rate. The effect of strain rate on fatigue life saturates at some low value, e.g., between 0.0004 and 0.001%/s in oxygenated water with ∼0.8 ppm DO. The data suggest that the saturation value of strain rate may vary with DO and sulfur content of the steel. Although the cyclic stress-strain and cyclic-hardening behavior of carbon and low-alloy steels is distinctly different, the degradation of fatigue life of these two steels with comparable sulfur levels is similar. The carbon steel exhibits pronounced dynamic strain aging, whereas strain-aging effects are modest in the low-alloy steel. Environmental effects on nucleation of fatigue crack have also been investigated. The results suggest that the high-temperature oxygenated water has little or not effect on crack nucleation

  16. On-line fatigue monitoring system for reactor pressure vessel

    International Nuclear Information System (INIS)

    Tokunaga, K.; Sakai, A.; Aoki, T.; Ranganath, S.; Stevens, G.L.

    1994-01-01

    A workstation-based, on-line fatigue monitoring system for tracking fatigue usage applied to an operating boiling water reactor (BWR), Tsuruga Unit-1, is described. The system uses the influence function approach and determines component stresses using temperature, pressure, and flow rate data that are made available via signal taps from previously existing plant sensors. Using plant unique influence functions developed specifically for the feedwater nozzle location, the system calculates stresses as a function of time and computed fatigue usage. The analysis method used to compute fatigue usage complies with MITI Code Notification No.501. Fatigue usage results for an entire fuel cycle are presented and compared to assumed design basis events to confirm that actual plant thermal duty is significantly less severe than originally estimated in the design basis stress report. As a result, the system provides the technical basis to more accurately evaluate actual reactor conditions as well as the justification for plant life extension. (author)

  17. Effect of HTGR helium on fatigue and creep properties of 2 1/4Cr-1Mo steel

    International Nuclear Information System (INIS)

    Kurumaji, T.; Yamazaki, H.; Kudo, A.

    1982-01-01

    Low cycle fatigue and creep tests have been carried out on 2 1/4Cr-1Mo steel (candidate steel for VHTR reactor pressure vessel) in helium environment containing 200 approx. 300 μatm of H 2 , 100 approx. 150 μatm CO, 7 approx. 10 μatm CH 4 , 7 approx. 10 μatm CO 2 and 1 μatm H 2 O (JAERI B Helium). Fatigue life in helium environment was longer than that in air at 450 0 C. This results can be explained by supposing that oxidation at the crack tip causes the wedge effect to promote crack propagation in air. On the otherhand, creep rupture strength showed no significant difference in both helium and air. Equivalent creep rupture strength in both helium and air may be due to the fact that detrimental internal oxidation and carburization or decarburization hardly occur at 400 approx. 450 0 C

  18. Residual stresses and fatigue in a duplex stainless steel

    International Nuclear Information System (INIS)

    Johansson, Johan

    1999-01-01

    Duplex stainless steels, consisting of approximately equal amounts of austenite and ferrite, often combine the best features of austenitic and ferritic stainless steels. They generally have good mechanical properties, including high strength and ductility, and the corrosion resistance is often better than conventional austenitic grades. This has lead to a growing use of duplex stainless steels as a material in mechanically loaded constructions. However, detailed knowledge regarding its mechanical properties and deformation mechanisms are still lacking. In this thesis special emphasis has been placed on the residual stresses and their influence on mechanical behaviour of duplex stainless steels. Due to the difference in coefficient of thermal expansion between the two phases, tensile microstresses are found in the austenitic phase and balancing compressive microstresses in the ferritic phase. The first part of this thesis is a literature survey, which will give an introduction to duplex stainless steels and review the fatigue properties of duplex stainless steels and the influence of residual stresses in two-phase material. The second part concerns the evolution of the residual stress state during uniaxial loading. Initial residual stresses were found to be almost two times higher in the transverse direction compared to the rolling direction. During loading the absolute value of the microstresses increased in the macroscopic elastic regime but started to decrease with increasing load in the macroscopic plastic regime. A significant increase of the microstresses was also found to occur during unloading. Finite element simulations also show stress variation within one phase and a strong influence of both the elastic and plastic anisotropy of the individual phases on the simulated stress state. In the third part, the load sharing between the phases during cyclic loading is studied. X-ray diffraction stress analysis and transmission electron microscopy show that even if

  19. Residual stresses and fatigue in a duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Johan

    1999-05-01

    Duplex stainless steels, consisting of approximately equal amounts of austenite and ferrite, often combine the best features of austenitic and ferritic stainless steels. They generally have good mechanical properties, including high strength and ductility, and the corrosion resistance is often better than conventional austenitic grades. This has lead to a growing use of duplex stainless steels as a material in mechanically loaded constructions. However, detailed knowledge regarding its mechanical properties and deformation mechanisms are still lacking. In this thesis special emphasis has been placed on the residual stresses and their influence on mechanical behaviour of duplex stainless steels. Due to the difference in coefficient of thermal expansion between the two phases, tensile microstresses are found in the austenitic phase and balancing compressive microstresses in the ferritic phase. The first part of this thesis is a literature survey, which will give an introduction to duplex stainless steels and review the fatigue properties of duplex stainless steels and the influence of residual stresses in two-phase material. The second part concerns the evolution of the residual stress state during uniaxial loading. Initial residual stresses were found to be almost two times higher in the transverse direction compared to the rolling direction. During loading the absolute value of the microstresses increased in the macroscopic elastic regime but started to decrease with increasing load in the macroscopic plastic regime. A significant increase of the microstresses was also found to occur during unloading. Finite element simulations also show stress variation within one phase and a strong influence of both the elastic and plastic anisotropy of the individual phases on the simulated stress state. In the third part, the load sharing between the phases during cyclic loading is studied. X-ray diffraction stress analysis and transmission electron microscopy show that even if

  20. Fatigue damage in coarse-grained lean duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Strubbia, R., E-mail: strubbia@ifir-conicet.gov.ar; Hereñú, S.; Marinelli, M.C.; Alvarez-Armas, I.

    2016-04-06

    The present investigation is focused on assessing the effect of a thermal treatment for grain coarsening on the low cycle fatigue damage evolution in two types of Lean Duplex Stainless Steels (LDSSs). The dislocation structure developed during cycling is observed by transmission electron microscopy (TEM). Additionally, a detailed analysis of short crack initiated and grown during low cycle fatigue (LCF) is performed by means of optical and scanning electron (SEM) microscopy in combination with automated electron back-scattered diffraction (EBSD) technique. Though in both coarse-grained LDSSs the short cracks nucleate in the ferrite phase, in each steels its origin is different. The embrittlement caused by the Cr{sub 2}N precipitation and the plastic activity sustained by each phase can explain this difference. The propagation behavior of the short cracks present two alternative growing mechanisms: the crack grows along a favorable slip plane with high Schmid Factor (SF) or the crack alternates between two slip systems. In both cases, the crack follows the path with the smallest tilt angle (β) at a grain boundary.

  1. Creep-fatigue-environment interaction of 9Cr-1Mo-V-Nb steel

    International Nuclear Information System (INIS)

    Shibata, Hiroyuki; Ishikawa, Akiyoshi; Asada, Yasuhide

    1996-01-01

    An extension of the creep-fatigue damage model has been conducted in the present study. The original damage model has been developed to the predict the creep-fatigue life of 9Cr-1Mo-V-Nb steel (Modified 9Cr-1Mo steel) in a very high vacuum environment. The present study is to extend an applicability of the model to the creep-fatigue damage accumulation in the air environment. (orig.)

  2. Effect of radiation damage on operating safety of steel pressure vessels of nuclear reactors

    International Nuclear Information System (INIS)

    Vacek, M.; Havel, S.; Stoces, B.; Brumovsky, M.

    1980-01-01

    The effects are assessed of the environment upon mechanical properties of steel used generally for pressure vessels of light water nuclear reactors. Changes caused by radiation affect the reliability of vessels. Deterioration of steel properties is mainly due to neutron radiation. The article deals with factors bearing upon damage and with methods allowing to evaluate the reliability of vessels and predict their service life. Operating reliability of vessels is very unfavourably affected by planned and accidental reactor transients. (author)

  3. Stable and unstable fatigue crack propagation during high temperature creep-fatigue in austenitic steels: the role of precipitation

    International Nuclear Information System (INIS)

    Lloyd, G.J.; Wareing, J.

    1979-01-01

    The distinction between stable and unstable fatigue crack propagation during high temperature creep-fatigue in austenitic stainless steels is introduced. The transition from one class of behavior to the other is related to the precipitate distribution and to the nature of the prevailing crack path. It is shown by reference to new studies and examples drawn from the literature that this behavior is common to both high strain and predominantly elastic fatigue in austenitic stainless steels. The relevance of this distinction to a mechanistic approach to high temperature plant design is discussed

  4. An experimental study on the effects of compressive stress on the fatigue crack growth of low-alloy steel

    International Nuclear Information System (INIS)

    Jones, D.P.; Hoppe, R.G.; James, B.A.

    1993-01-01

    A series of fatigue crack growth rate tests was conducted in order to study effects of negative stress ratio on fatigue crack growth rate of low-alloy steel in air. Four-point bend specimens were used to simulate linear stress distributions typical of pressure vessel applications. This type of testing adds to knowledge on negative stress ratio effects for low-alloy steels obtained in the past from uniform tension-compression tests. Applied bending stress range was varied over twice the yield strength. Load control was used for tests for which the stress range was less than twice the yield strength and deflection control was used for the higher stress range tests. Crack geometries were both short and long fatigue cracks started at notches and tight fatigue cracks for which crack closure could occur over the full crack face. Results are presented in terms of the stress intensity factor ratio R = K MIN /K MAX . The negative R-ratio test results were correlated to an equation of the form da/dN = C[ΔK/(A-R)] n , where A, C, and n are curve fitting parameters. It was found that effects of negative R-ratio on fatigue crack growth rates for even the high stress range tests could be bounded by correlating the above equation to only positive R-ratio test results and extending the resulting equation into the negative R-ratio regime

  5. Dynamic fracture characterization of a pressure vessel steel

    International Nuclear Information System (INIS)

    Schmitt, W.; Boehme, W.; Klemm, W.; Memhard, D.; Winkler, S.

    1991-01-01

    Dynamic events are characterized by time and space-dependent stress and strain fields caused by wave or inertia effect. The dynamic effect at cracks may be originated from the rapid loading rate or impact loading of a structure containing a stationary crack or the time-dependent stress and strain fields of a propagating or arresting crack itself. Dynamic effects complicate the analysis of crack tip stress and strain fields, and usually considerable experimental effort and numerical technique are required. High loading rate influences the deformation and yield behavior and also the fracture toughness of materials. In order to know the propagation and arrest behavior of cracks, a heat of a German reactor pressure vessel steel was investigated, and the dynamic J-resistance curves were evaluated with large three-point bending specimens by impact loading, moreover, the crack propagation energy at large crack extension was determined with wide tension plates. The material tested was a ferritic pressure vessel steel, ASTM A 508 Cl 2. The dynamic J-resistance curves and numerical simulation and fractographic examination, and crack propagation energy are reported. (K.I.)

  6. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels

    OpenAIRE

    Wang, Yanhui; Zhang, Fucheng; Yang, Zhinan; Lv, Bo; Zheng, Chunlei

    2016-01-01

    In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF) performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plat...

  7. Cyclic fatigue of a high-strength corrosion-resistant sheet TRIP steel

    Science.gov (United States)

    Terent'ev, V. F.; Alekseeva, L. E.; Korableva, S. A.; Prosvirnin, D. V.; Pankova, M. N.; Filippov, G. A.

    2014-04-01

    The mechanical properties of 0.3- and 0.8-mm-thick high-strength corrosion-resistant TRIP steel having various levels of strength properties are studied during static and cyclic loading in the high-cycle fatigue range. The fatigue fracture surface is analyzed by fractography, and the obtained results demonstrate ductile and quasi-brittle fracture mechanisms of this steel depending on the strength properties of the steel and the content of deformation martensite in it.

  8. Interfacial fatigue stress in PVD TiN coated tool steels under rolling contact fatigue conditions

    OpenAIRE

    Carvalho, N.J.M.; Huis in ’t Veld, A.J.; Hosson, J.Th. De

    1998-01-01

    Titanium–nitrogen (TiN) films were Physical Vapour Deposited (PVD) on tool steel substrates with different hardness and surface roughness, in a Bai 640R unit using a triode ion plating (e-gun) with a high plasma density. The coated substrates were submitted to a rolling contact fatigue test technique (modified pin-on-ring test) to obtain some clarifications of the mechanism of interfacial failure. Tests were run using PVD-coated rings finished by polishing or grinding to produce different sur...

  9. Residual stresses in weld-clad reactor pressure vessel steel

    International Nuclear Information System (INIS)

    Bertram, W.

    1975-01-01

    Cladding of low alloy nuclear reactor pressure vessel steel with austenitic stainless steel introduces in heavy section components high residual stresses which may cause microcrack formation in stress relief heat treatment. In this investigation an attempt is made to contribute to the solution of the stress relief cracking problem by determining quantitatively the magnitude and distribution of the residual stresses after cladding and after subsequent stress relief heat treatment. The distribution of residual stresses was determined on the basis of a combined experimental-mathematical procedure. Heavy section plate specimens of low alloy steel as base material were given an austenitic monolayer-cladding using the techniques of strip electrode and plasma hot wire cladding, respectively. A number of plates was stress relief heat treated. Starting from the cladded surface the thickness of the plates was reduced by subsequent removal of layers of material. The elastic strain reaction to the removal of each layer was measured by strain gauges. From the data obtained the biaxial residual stress distribution was computed as a function of thickness using relations which are derived for this particular case. In summary, lower residual stresses are caused by reduced thickness of the components. As the heat input, is decreased at identical base material thickness, the residual stresses are lowered also. The height of the tensile residual stress peak, however, remains approximataly constant. In stress relief annealed condition the residual stresses in the cladding are in tension; in the base material the residual stresses are negligibly small

  10. Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

    2015-01-01

    Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

  11. Investigation of LWR environmental effect on fatigue lifetime of austenitic stainless steel component

    International Nuclear Information System (INIS)

    Kim, J. S.; Youm, H. K.; Jin, T. E.

    1999-01-01

    The fatigue lifetime of principal components in nuclear power plant is evaluated by using the design fatigue curves in ASME B and PV code during design process. However, it is inadequate to evaluate fatigue lifetime considering the LWR environmental effect by these design fatigue curves because these are presented only under atmosphere environment. Therefore, many studies are recently performed for the design fatigue curves considering LWR environmental effect and are presented that the design fatigue curves in ASME B and PV code can be non-conservative. In present paper, the limits and differences of the design fatigue curves considering environmental effect are presented. To investigate the change of fatigue lifetime according to each design fatigue curve, the CUFs for the pressurizer spray nozzle partly composed of austenitic stainless steel are calculated according to each one. Finally, if the evaluation result can not be satisfied with fatigue design requirement, the alternatives to reduce design cumulative usage factor are discussed. (author)

  12. Mechanical properties and fatigue strength of high manganese non-magnetic steel/carbon steel welded joints

    International Nuclear Information System (INIS)

    Nakaji, Eiji; Ikeda, Soichi; Kim, You-Chul; Nakatsuji, Yoshihiro; Horikawa, Kosuke.

    1997-01-01

    The dissimilar materials welded joints of high manganese non-magnetic steel/carbon steel (hereafter referred to as DMW joints), in which weld defects such as hot crack or blowhole are not found, were the good quality. Tensile strength of DMW joints was 10% higher than that of the base metal of carbon steel. In the bend tests, the DMW joints showed the good ductility without crack. Charpy absorbed energy at 0(degC) of the DMW joints was over 120(J) in the bond where it seems to be the lowest. Large hardening or softening was not detected in the heat affected zone. Fatigue strength of the DMW joints is almost the same with that of the welded joints of carbon steel/carbon steel. As the fatigue strength of the DMW joints exceeds the fatigue design standard curve of JSSC for carbon steel welded joints, the DMW joints can be treated the same as the welded joints of carbon steel/carbon steel of which strength is lower than that of high manganese non-magnetic steel, from the viewpoint of the fatigue design. (author)

  13. Flexural fracture and fatigue behavior of steel-fiber-reinforced concrete structures

    International Nuclear Information System (INIS)

    Chang, D.I.

    1995-01-01

    Fracture and fatigue tests were performed in order to investigate the fracture and fatigue behavior of steel-fibre-reinforced concrete (SFRC) structures. 33 SFRC beams were used in the fracture and fatigue tests. The relationship between loading, strain and midspan deflection of the beams was observed under the three-point loading system.From the test results, the effects of the fiber content, fiber aspect ratio and notch-to-depth ratio on the concrete fracture and fatigue behavior were studied, and the fatigue strengths of SFRC beams were calculated. According to the regression technique, some empirical formulae for predicting the fatigue strength of SFRC beams were also suggested. (orig.)

  14. A Constitutive Relationship between Fatigue Limit and Microstructure in Nanostructured Bainitic Steels

    Science.gov (United States)

    Mueller, Inga; Rementeria, Rosalia; Caballero, Francisca G.; Kuntz, Matthias; Sourmail, Thomas; Kerscher, Eberhard

    2016-01-01

    The recently developed nanobainitic steels show high strength as well as high ductility. Although this combination seems to be promising for fatigue design, fatigue properties of nanostructured bainitic steels are often surprisingly low. To improve the fatigue behavior, an understanding of the correlation between the nanobainitic microstructure and the fatigue limit is fundamental. Therefore, our hypothesis to predict the fatigue limit was that the main function of the microstructure is not necessarily totally avoiding the initiation of a fatigue crack, but the microstructure has to increase the ability to decelerate or to stop a growing fatigue crack. Thus, the key to understanding the fatigue behavior of nanostructured bainite is to understand the role of the microstructural features that could act as barriers for growing fatigue cracks. To prove this hypothesis, we carried out fatigue tests, crack growth experiments, and correlated these results to the size of microstructural features gained from microstructural analysis by light optical microscope and EBSD-measurements. Finally, we were able to identify microstructural features that influence the fatigue crack growth and the fatigue limit of nanostructured bainitic steels. PMID:28773953

  15. A Constitutive Relationship between Fatigue Limit and Microstructure in Nanostructured Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Inga Mueller

    2016-10-01

    Full Text Available The recently developed nanobainitic steels show high strength as well as high ductility. Although this combination seems to be promising for fatigue design, fatigue properties of nanostructured bainitic steels are often surprisingly low. To improve the fatigue behavior, an understanding of the correlation between the nanobainitic microstructure and the fatigue limit is fundamental. Therefore, our hypothesis to predict the fatigue limit was that the main function of the microstructure is not necessarily totally avoiding the initiation of a fatigue crack, but the microstructure has to increase the ability to decelerate or to stop a growing fatigue crack. Thus, the key to understanding the fatigue behavior of nanostructured bainite is to understand the role of the microstructural features that could act as barriers for growing fatigue cracks. To prove this hypothesis, we carried out fatigue tests, crack growth experiments, and correlated these results to the size of microstructural features gained from microstructural analysis by light optical microscope and EBSD-measurements. Finally, we were able to identify microstructural features that influence the fatigue crack growth and the fatigue limit of nanostructured bainitic steels.

  16. An investigation on fatigue in high-strength steel offshore structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1998-01-01

    of the investigation, fatigue test series were carried out on both full scale tubular joints and smaller welded plate test specimens in high-strength steel as well as in conventional offshore structural steel. This paper gives a summary of the main results presented in two recent research reports [15, 16], from...... these investigations. A comparison between constant amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula.Furthermore, in general longer fatigue lives were obtained for the test...... specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  17. An Investigation on Fatigue in High-Strength Steel Offshore Structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Lopez Martinez, L.

    1997-01-01

    . In the experimental part of the investigation, fatigue test series have been carried through on both full-scale tubular joints and smaller welded plate test specimens, in high-strength steel as well as in conventional offshore structural steel. The present document gives a summary of the main results presented in two...... recent research reports, Refs. 15 and 16, from these investigations.A comparison between constant amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore......, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  18. Effect of pre-strain history on small crack growth under low cycle fatigue for JIS SFVQ1A steel

    International Nuclear Information System (INIS)

    Hasunuma, Shota; Miyata, Yohei; Sakaue, Kenichi; Ogawa, Takeshi

    2011-01-01

    Low cycle fatigue tests were performed for a low alloy steel, JIS SFVQ1A, used for pressure vessels of nuclear power plants. The effect of pre-strain history on the small crack initiation and growth was investigated in detail using cellulose acetate replicas. Under the tests in which the total strain range, Δε, is constant, surface crack length, 2c, was smaller for the tests with larger Δε due to the different numbers of small crack initiation and coalescence. The pre-strain histories were applied at Δε of 8 or 16% with its fatigue usage factor, UF, of less than 0.2, followed by fatigue loading at Δε=2% until fracture. In these tests, the relationships between 2c and UF agreed with each other unless crack coalescence occurred. The scatter in fatigue life was attributed to the coalescences of small cracks. Fracture mechanics approach was applied to predict the fatigue lives and to characterize the growth behavior of small fatigue cracks. (author)

  19. Estimating the Contact Endurance of the AISI 321 Stainless Steel Under Contact Gigacycle Fatigue Tests

    Science.gov (United States)

    Savrai, R. A.; Makarov, A. V.; Osintseva, A. L.; Malygina, I. Yu.

    2018-02-01

    Mechanical testing of the AISI 321 corrosion resistant austenitic steel for contact gigacycle fatigue has been conducted with the application of a new method of contact fatigue testing with ultrasonic frequency of loading according to a pulsing impact "plane-to-plane" contact scheme. It has been found that the contact endurance (the ability to resist the fatigue spalling) of the AISI 321 steel under contact gigacycle fatigue loading is determined by its plasticity margin and the possibility of additional hardening under contact loading. It is demonstrated that the appearance of localized deep and long areas of spalling on a material surface can serve as a qualitative characteristic for the loss of the fatigue strength of the AISI 321 steel under impact contact fatigue loading. The value of surface microhardness measured within contact spots and the maximum depth of contact damages in the peripheral zone of contact spots can serve as quantitative criteria for that purpose.

  20. Influence of Prior Fatigue Cycling on Creep Behavior of Reduced Activation Ferritic-Martensitic Steel

    Science.gov (United States)

    Sarkar, Aritra; Vijayanand, V. D.; Parameswaran, P.; Shankar, Vani; Sandhya, R.; Laha, K.; Mathew, M. D.; Jayakumar, T.; Rajendra Kumar, E.

    2014-06-01

    Creep tests were carried out at 823 K (550 °C) and 210 MPa on Reduced Activation Ferritic-Martensitic (RAFM) steel which was subjected to different extents of prior fatigue exposure at 823 K at a strain amplitude of ±0.6 pct to assess the effect of prior fatigue exposure on creep behavior. Extensive cyclic softening that characterized the fatigue damage was found to be immensely deleterious for creep strength of the tempered martensitic steel. Creep rupture life was reduced to 60 pct of that of the virgin steel when the steel was exposed to as low as 1 pct of fatigue life. However, creep life saturated after fatigue exposure of 40 pct. Increase in minimum creep rate and decrease in creep rupture ductility with a saturating trend were observed with prior fatigue exposures. To substantiate these findings, detailed transmission electron microscopy studies were carried out on the steel. With fatigue exposures, extensive recovery of martensitic-lath structure was distinctly observed which supported the cyclic softening behavior that was introduced due to prior fatigue. Consequently, prior fatigue exposures were considered responsible for decrease in creep ductility and associated reduction in the creep rupture strength.

  1. Assessment of environmentally assisted cracking in PWR pressure vessel steels

    International Nuclear Information System (INIS)

    Tice, D.R.

    1991-01-01

    There is a possibility that extension of pre-existing flaws in the reactor pressure vessel of a pressurised water reactor (PWR) may occur by environmentally assisted cracking, in particular by corrosion fatigue under cyclic transient loading. Crack growth predictions have usually been carried out using cyclic crack growth rate (da/dN) versus stress intensity range (δK) curves, such as those given in Section XI, Appendix A of the ASME Boiler and Pressure Vessel Code. However, the inherent time dependent nature of environmental cracking processes renders such an approach unrealistic. The present paper describes the development of an alternative time based assessment methodology. Illustrative calculations of expected crack growth of assumed defects made using the cyclic (ASME XIA) and time-based approaches are compared. The results illustrate that crack growth predicted by the time-based approach can be greater or less than that calculated by the traditional method. For a PWR operated with good control of water chemistry, actual crack growth rates are expected to be well below those predicted by the ASME code. (Author)

  2. Hull Girder Fatigue Damage Estimations of a Large Container Vessel by Spectral Analysis

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

    2013-01-01

    This paper deals with fatigue damage estimation from the analysis of full-scale stress measurements in the hull of a large container vessel (9,400 TEU) covering several months of operation. For onboard decision support and hull monitoring sys-tems, there is a need for a fast reliable method...... for esti-mation of fatigue damage in the ship hull. The objective of the study is to investigate whether the higher frequency contributions from the hydroelastic responses (springing and whipping) can satisfactory be included in the fatigue damage estimation by only a few parameters derived from the stress...

  3. Environmental Assisted Fatigue Evaluation of Direct Vessel Injection Piping Considering Thermal Stratification

    International Nuclear Information System (INIS)

    Kim, Taesoon; Lee, Dohwan

    2016-01-01

    As the environmentally assisted fatigue (EAF) due to the primary water conditions is to be a critical issue, the fatigue evaluation for the components and pipes exposed to light water reactor coolant conditions has become increasingly important. Therefore, many studies to evaluate the fatigue life of the components and pipes in LWR coolant environments on fatigue life of materials have been conducted. Among many components and pipes of nuclear power plants, the direct vessel injection piping is known to one of the most vulnerable pipe systems because of thermal stratification occurred in that systems. Thermal stratification occurs because the density of water changes significantly with temperature. In this study, fatigue analysis for DVI piping using finite element analysis has been conducted and those results showed that the results met design conditions related with the environmental fatigue evaluation of safety class 1 pipes in nuclear power plants. Structural and fatigue integrity for the DVI piping system that thermal stratification occurred during the plant operation has conducted. First of all, thermal distribution of the piping system is calculated by computational fluid dynamic analysis to analyze the structural integrity of that piping system. And the fatigue life evaluation considering environmental effects was carried out. Our results showed that the DVI piping system had enough structural integrity and fatigue life during the design lifetime of 60 years

  4. Effect of aging on properties of pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Druce, S.G.; Gage, G.; Jordan, G.

    1986-04-01

    Manganese-molybdenum-nickel steels are used in nuclear pressure vessels operating at temperatures up to 350/sup 0/C. The effects of thermal ageing in the temperature range 300-550/sup 0/C for durations up to 2 x 10/sup 4/ h have been studied in conventionally quenched and tempered and simulated heat-affected-zone (HAZ) microstructural conditions. Quantitative fractography and Auger spectroscopy have been used to relate changes in mechanical properties with changes in fracture mode and grain boundary chemistry. Aging increases the ductile-brittle transition temperature by an amount dependent on material, prior heat treatment, aging temperature and time. Embrittlement is associated with segregation of phosphorus to grain boundaries and is modelled using McLean's approach to equilibrium segregation.

  5. Influence of Pavement on Fatigue Performance of Urban Steel Box Girder Deck

    Directory of Open Access Journals (Sweden)

    Zheng Zhongyue

    2016-01-01

    Full Text Available Based on spatial finite element analysis method, the Influence of pavement on fatigue performance of orthotropic steel deck was analyzed in terms of pavement system, asphalt pavement stiffness. The result shows that compared with asphalt pavement system, RPC pavement system can not only obviously improve the stress condition of steel bridge deck, but also significantly extend the fatigue life of steel bridge panel; Increasing the stiffness of pavement layer can obviously reduce the stress amplitude of fatigue details, especially for direct contact with the pavement.

  6. Fatigue of DIN 1.4914 martensitic stainless steel in a hydrogen environment

    Science.gov (United States)

    Shakib, J. I.; Ullmaier, H.; Little, E. A.; Faulkner, R. G.; Schmilz, W.; Chung, T. E.

    1994-09-01

    Fatigue tests at room temperature in vacuum, air and hydrogen have been carried out on specimens of DIN 1.4914 martensitic stainless steel in load-controlled, push-pull type experiments. Fatigue lifetimes in hydrogen are significantly lower than in both vacuum and air and the degradation is enhanced by lowering the test frequency or introducing hold times into the tension half-cycle. Fractographic examinations reveal hydrogen embrittlement effects in the form of internal cracking between fatigue striations together with surface modifications, particularly at low stress amplitudes. It is suggested that gaseous hydrogen can influence both fatigue crack initiation and propagation events in martensitic steels.

  7. The creep-fatigue crack growth behaviour of a 1CrMoV rotor steel

    International Nuclear Information System (INIS)

    Priest, R.H.; Miller, D.A.; Gladwin, D.N.; Maguire, J.

    1989-01-01

    Crack growth rates under simultaneous creep-fatigue conditions have been quantified for a 1CrMoV rotor steel. Measured growth rates were partitioned into cyclic and hold period contributions and these characterized by the relevant fracture mechanics parameters K and C. Cyclic growth rates measured in the creep-fatigue tests were enhanced compared with pure fatigue rates. This observation is compared with the behaviour of other steels and explained by quantitative metallography. The resulting crack growth equation can be used during integrity assessments for plant components containing cracks which are subject to thermal fatigue

  8. Study on creep-fatigue life improvement and life evaluation of 316FR stainless steels

    International Nuclear Information System (INIS)

    Kobayashi, Kazuo; Yamaguchi, Koji; Yamazaki, Masayoshi; Hongo, Hiromichi; Nakazawa, Takanori; Date, Shingo; Tendo, Masayuki

    2000-01-01

    Creep rupture and creep-fatigue interaction tests were conducted at 550deg C for modified 316FR austenitic stainless steels in order to improve the creep-fatigue lives. Reducing the carbon contents from 0.01% to 0.002 or 0.003% and finning the grain size were effective for increasing the creep-fatigue lives and the creep rupture ductilities. From these results, an estimation method of the creep-fatigue lives by using the creep rupture ductilities in the modified 316FR steels was proposed. (author)

  9. Neutron irradiation embrittlement of reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Steele, L.E.

    1975-01-01

    The reliability of nuclear power plants depends on the proper functioning of complex components over the whole life on the plant. Particular concern for reliability is directed to the primary pressure boundary. This report focuses on the portion of the primary system exposed to and significantly affected by neutron radiation. Experimental evidence from research programmes and from reactor surveillance programmes has indicated radiation embrittlement of a magnitude sufficient to raise doubts about reactor pressure vessel integrity. The crucial nature of the primary vessel function heightens the need to be alert to this problem, to which, fortunately, there are positive aspects: for example, steels have been developed which are relatively immune to radiation embrittlement. Further, awareness of such embrittlement has led to designs which can accomodate this factor. The nature of nuclear reactors, of the steels used in their construction, and of the procedures for interpreting embrittlement and minimizing the effects are reviewed with reference to the reactors that are expected to play a major role in electric power production from now to about the turn of the century. The report is intended as a manual or guidebook; the aim has been to make each chapter or major sub-division sufficiently comprehensive and self-contained for it to be understood and read independently of the rest of the book. At the same time, it is hoped that the whole is unified enough to make a complete reading useful and interesting to the several classes of reader that are involved with only specific aspects of the topic

  10. Effect of a new specimen size on fatigue crack growth behavior in thick-walled pressure vessels

    International Nuclear Information System (INIS)

    Shariati, Mahmoud; Mohammadi, Ehsan; Masoudi Nejad, Reza

    2017-01-01

    Fatigue crack growth in thick-walled pressure vessels is an important factor affecting their fracture. Predicting the path of fatigue crack growth in a pressure vessel is the main issue discussed in fracture mechanics. The objective of this paper is to design a new geometrical specimen in fatigue to define the behavior of semi-elliptical crack growth in thick-walled pressure vessels. In the present work, the importance of the behavior of fatigue crack in test specimen and real conditions in thick-walled pressure vessels is investigated. The results of fatigue loading on the new specimen are compared with the results of fatigue loading in a cylindrical pressure vessel and a standard specimen. Numerical and experimental methods are used to investigate the behavior of fatigue crack growth in the new specimen. For this purpose, a three-dimensional boundary element method is used for fatigue crack growth under stress field. The modified Paris model is used to estimate fatigue crack growth rates. In order to verify the numerical results, fatigue test is carried out on a couple of specimens with a new geometry made of ck45. A comparison between experimental and numerical results has shown good agreement. - Highlights: • This paper provides a new specimen to define the behavior of fatigue crack growth. • We estimate the behavior of fatigue crack growth in specimen and pressure vessel. • A 3D finite element model has been applied to estimate the fatigue life. • We compare the results of fatigue loading for cylindrical vessel and specimens. • Comparison between experimental and numerical results has shown a good agreement.

  11. Research to sustain cases for Magnox-reactor steel pressure vessels

    International Nuclear Information System (INIS)

    Graham, W.J.

    1997-01-01

    Britain's Magnox Electric plc owns and operates six power stations, each of which has twin gas-cooled reactors of the Magnox-fuel type. The older group of four power stations has steel pressure-circuits. The reactor cores are housed within spherical, steel vessels. This article describes some of the research which is undertaken to sustain the safety cases for these steel vessels which have now been in operation for just over 30 years. (author) 2 figs., 4 refs

  12. Shallow-crack toughness results for reactor pressure vessel steel

    International Nuclear Information System (INIS)

    Theiss, T.J.; Shum, D.K.M.; Rolfe, S.T.

    1992-01-01

    The Heavy Section Steel Technology Program (HSST) is investigating the influence of flaw depth on the fracture toughness of reactor pressure vessel (RPV) steel. To complete this investigation, techniques were developed to determine the fracture toughness from shallow-crack specimens. A total of 38 deep and shallow-crack tests have been performed on beam specimens about 100 mm deep loaded in 3-point bending. Two crack depths (a ∼ 50 and 9 mm) and three beam thicknesses (B ∼ 50, 100, and 150 mm) have been tested. Techniques were developed to estimate the toughness in terms of both the J-integral and crack-tip opening displacement (CTOD). Analytical J-integral results were consistent with experimental J-integral results, confirming the validity of the J-estimation schemes used and the effect of flaw depth on fracture toughness. Test results indicate a significant increase in the fracture toughness associated with the shallow flaw specimens in the lower transition region compared to the deep-crack fracture toughness. There is, however, little or no difference in toughness on the lower shelf where linear-elastic conditions exist for specimens with either deep or shallow flaws. The increase in shallow-flaw toughness compared with deep-flaw results appears to be well characterized by a temperature shift of 35 degree C

  13. The measured contribution of whipping and springing on the fatigue and extreme loading of container vessels

    Science.gov (United States)

    Storhaug, Gaute

    2014-12-01

    Whipping/springing research started in the 50'ies. In the 60'ies inland water vessels design rules became stricter due to whipping/springing. The research during the 70-90'ies may be regarded as academic. In 2000 a large ore carrier was strengthened due to severe cracking from North Atlantic operation, and whipping/springing contributed to half of the fatigue damage. Measurement campaigns on blunt and slender vessels were initiated. A few blunt ships were designed to account for whipping/springing. Based on the measurements, the focus shifted from fatigue to extreme loading. In 2005 model tests of a 4,400 TEU container vessel included extreme whipping scenarios. In 2007 the 4400 TEU vessel MSC Napoli broke in two under similar conditions. In 2009 model tests of an 8,600 TEU container vessel container vessel included extreme whipping scenarios. In 2013 the 8,100 TEU vessel MOL COMFORT broke in two under similar conditions. Several classification societies have published voluntary guidelines, which have been used to include whipping/springing in the design of several container vessels. This paper covers results from model tests and full scale measurements used as background for the DNV Legacy guideline. Uncertainties are discussed and recommendations are given in order to obtain useful data. Whipping/springing is no longer academic.

  14. High-cycle fatigue behavior of ultrafine-grained austenitic stainless and TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, A.S. [Materials Engineering Laboratory (4KOMT), Box 4200, University of Oulu, 90014 Oulu (Finland); Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez Canal University, Box 43721, Suez (Egypt); Karjalainen, L.P., E-mail: pentti.karjalainen@oulu.fi [Materials Engineering Laboratory (4KOMT), Box 4200, University of Oulu, 90014 Oulu (Finland)

    2010-08-20

    High-cycle fatigue behavior of ultrafine-grained (UFG) 17Cr-7Ni Type 301LN austenitic stainless and high-Mn Fe-22Mn-0.6C TWIP steels were investigated in a reversed plane bending fatigue and compared to the behavior of steels with conventional coarse grain (CG) size. Optical, scanning and transmission electron microscopy were used to examine fatigue damage mechanisms. Testing showed that the fatigue limits leading to fatigue life beyond 4 x 10{sup 6} cycles were about 630 MPa for 301LN while being 560 MPa for TWIP steel, and being 0.59 and 0.5 of the tensile strength respectively. The CG counterparts were measured to have the fatigue limits of 350 and 400 MPa. The primary damage caused by fatigue took place by grain boundary cracking in UFG 301LN, while slip band cracking occurred in CG 301LN. However, in the case of TWIP steel, the fatigue damage mechanism is similar in spite of the grain size. In the course of cycling neither the formation of a martensite structure nor mechanical twinning occurs, but intense slip bands are created with extrusions and intrusions. Fatigue crack initiates preferentially on grain and twin boundaries, and especially in the intersection sites of slip bands and boundaries.

  15. Low cycle fatigue behaviors of low alloy steels in 310 .deg. C deoxygenated water

    International Nuclear Information System (INIS)

    Jang, Hun

    2008-02-01

    After low cycle fatigue tests of SA508 Gr.1a low alloy steel in 310 .deg. C deoxygenated water, the fatigue surface and the sectioned area of specimens were observed to understand the effect of the cyclic strain rate on the environmentally assisted cracking behaviors. From the fatigue crack morphologies of the specimen tested at a strain rate of 0.008 %/s, unclear ductile striations and blunt crack tip were observed. So, metal dissolution could be the main cracking mechanism of the material at the strain rate. On the other hand, on the fatigue surface of the specimen tested at strain rates of 0.04 and 0.4 %/s, the brittle cracks and the flat facets, which are the evidence of the hydrogen induced cracking, were observed. Also, the tendency of linkage between the main crack and micro-cracks was observed on the sectioned area. Therefore, the main cracking mechanism at the strain rates of 0.04 and 0.4 %/s could be the hydrogen induced cracking. Additionally, the evidence of the dissolved MnS inclusions was observed on the fatigue surface from energy dispersive x-ray spectrometer analyses. So, despite of the low sulfur content of the test material, the sulfides seem to contribute to environmentally assisted cracking of SA508 Gr.1a low alloy steel in 310 .deg. C deoxygenated water. Additionally, our experimental fatigue life data of SA508 Gr.1a low alloy steel (heat A) showed a consistent difference with statistical model produced in argon national laboratory. So, additional low cycle fatigue tests of other heat SA508 Gr.1a (heat B) and SA508 Gr.3 low alloy steels were performed to investigate the effect of material variability on fatigue behaviors of low alloy steels in 310 .deg. C deoxygenated water. In results, the fatigue lives of three low alloy steels were increased following order: SA508 Gr.1a low alloy steel - heat A, SA508 Gr.3 low alloy steel, and SA508 Gr.1a low alloy steel - heat B. From microstructure observation, the fatigue surface of SA508 Gr.1a low alloy

  16. Low-cycle fatigue behaviors of pre-hardening Hadfield steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, Bo [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Fei [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Fucheng, E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China)

    2017-05-17

    Low-cycle fatigue behaviors of the pre-hardening (PH) and the water-quenching (WQ) Hadfield steel were studied using optical microscopy, transmission electron microscopy, and electron backscatter diffraction technique. The effect of the PH treatment on low-cycle fatigue behavior of the Hadfield steel was analyzed through comparing the cyclic hardening/softening behaviors and the changing regulations of stress amplitude, internal stress, and effective stress at different total strain amplitudes. Results showed obvious differences in fatigue behaviors between the PH (with a cold rolling deformation degree of 40%) and the WQ Hadfield steels. Transient hardening followed by cyclic stability behavior occurred in the PH Hadfield steel under cyclic loading, whereas cyclic softening behavior was barely observed. The fatigue life of the PH Hadfield steel was higher than that of the WQ Hadfield steel at relatively low strain amplitudes, while a contrary result was obtained at relatively high strain amplitudes. At low strain amplitudes, the deformation twins induced in the PH Hadfield steel could enhance the multiplication and slip process of dislocations, which actually improved the deformation uniformity. The long-range motion of dislocations was intensified at high strain amplitudes. However, the dislocation motion was also blocked by twin boundaries. As a result, the interactions between dislocations and deformation twins enhanced, finally causing severe dislocation accumulation. These two effects of deformation twins on dislocation motion eventually resulted in different low-cycle fatigue behaviors of the PH Hadfield steel.

  17. Surveillance of evolution of defects in stainless steel piping subject to fatigue cycles in temperature

    International Nuclear Information System (INIS)

    Marini, J.

    1976-01-01

    The surveillance of internal crack growth in austenitic ICL 167 CN steel is possible by using ultrasonic techniques. The fracture mechanics allows to predict the evolution of these cracks under fatigue loading [fr

  18. Mechanical Suppression of SCC and Corrosion Fatigue Failures in 300M Steel Landing Gear

    National Research Council Canada - National Science Library

    Prevey, Paul; Jayaraman, N; Ontko, Neal; Shepard, Mike; Ware, Robert; Coate, Jack

    2004-01-01

    300M steel is widely used in landing gear because of its ultra high strength with high fracture toughness, but is vulnerable to both corrosion fatigue and stress corrosion cracking, with potentially...

  19. Development of elevated temperature fatigue design information for type 316 stainless steel

    International Nuclear Information System (INIS)

    Jaske, C.E.; Mindlin, H.; Perrin, J.S.

    1975-01-01

    To develop material properties information for use in elevated-temperature fatigue design, an extensive study of the fatigue and stress-strain behaviour of Type 316 stainless steel was conducted at temperatures from 21 to 649 0 C. Fatigue life and cyclic stress-strain curves were developed. Creep-fatigue interaction was evaluated by conducting strain hold-time tests at 566 and 649 0 C. Hold periods at peak tensile strain produced a large reduction in cyclic life. It was found that both a linear damage rule and the strain-partitioning method could be used to assess cumulative creep and fatigue damage. Aging for 1000 h at test temperature before testing caused only small or no changes in continuous cycling fatigue resistance at 566 and 649 0 C and in tension hold-time fatigue resistance at 566 0 C. This aging produced a significant increase in tension hold-time fatigue resistance at 649 0 C. (author)

  20. X-ray diffraction study of microstructural changes during fatigue damage initiation in steel pipes

    Energy Technology Data Exchange (ETDEWEB)

    Pinheiro, B., E-mail: bianca@lts.coppe.ufrj.br [Laboratory of Mechanics of Lille (LML), UMR CNRS 8107, University of Lille 1, Boulevard Paul Langevin, Cite Scientifique, 59655 Villeneuve d' Ascq (France); Lesage, J. [Laboratory of Mechanics of Lille (LML), UMR CNRS 8107, University of Lille 1, Boulevard Paul Langevin, Cite Scientifique, 59655 Villeneuve d' Ascq (France); Pasqualino, I. [Subsea Technology Laboratory (LTS), Ocean Engineering Department, COPPE/Federal University of Rio de Janeiro, PO Box 68508, Cidade Universitaria, CEP 21945-970, Rio de Janeiro/RJ (Brazil); Benseddiq, N. [Laboratory of Mechanics of Lille (LML), UMR CNRS 8107, University of Lille 1, Boulevard Paul Langevin, Cite Scientifique, 59655 Villeneuve d' Ascq (France); Bemporad, E. [Interdepartmental Laboratory of Electron Microscopy (LIME), University of Rome TRE, Via Della Vasca Navale 79, 00146 Rome (Italy)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer In this work we study the fatigue damage evolution in an API 5L X60 steel. Black-Right-Pointing-Pointer Microstructural changes and residual stresses are evaluated during fatigue tests. Black-Right-Pointing-Pointer Microdeformations and macro residual stresses are estimated by X-ray diffraction. Black-Right-Pointing-Pointer Results are discussed in view of an indicator of fatigue damage initiation. Black-Right-Pointing-Pointer This indicator could allow the prediction of residual life before macrocracking. - Abstract: Steel pipes used in the oil and gas industry undergo the action of cyclic loads that can cause their failure by fatigue. A consistent evaluation of the fatigue damage during the initiation phase should fundamentally be based on a nanoscale approach, i.e., at the scale of the dislocation network, in order to take into account the micromechanisms of fatigue damage that precede macrocrack initiation and propagation until the final fracture. In this work, microstructural changes related to fatigue damage initiation are investigated in the API 5L X60 grade steel, used in pipe manufacturing. Microdeformations and macro residual stress are evaluated using X-ray diffraction in real time during alternating bending fatigue tests performed on samples cut off from an X60 steel pipe. The aim of this ongoing work is to provide ground for further development of an indicator of fatigue damage initiation in X60 steel. This damage indicator could allow a good residual life prediction of steel pipes previously submitted to fatigue loading, before macroscopic cracking, and help to increase the reliability of these structures.

  1. Investigation of magnetic properties of steel in the process of fatigue

    International Nuclear Information System (INIS)

    Kasimov, G.A.; Pokrovskij, A.D.

    1976-01-01

    Non-destructive method was developed for the recognition of structural demages of mashine components, which is based on studying the effect of the cyclical loading of constructional steel (brands 10, 20, etc.) upon their magnetic characteristics. Using the experimental installation, we have determined the effect of the degree of fatigue destruction of steel specimens upon the main magnetization curve and the symmetrical cycles of magnetic hysteresis. The obtained results make it possible to choose the conditions of control over the fatigue process

  2. An Intelligent Sensor System for Monitoring Fatigue Damage in Welded Steel Components

    Science.gov (United States)

    Fernandes, B.; Gaydecki, P.; Burdekin, F. Michael

    2005-04-01

    A system for monitoring fatigue damage in steel components is described. The sensor, a thin steel sheet with a pre-crack in it, is attached to the component. Its crack length increases by fatigue in service and is recorded using a microcontroller. Measurement is accomplished using conductive tracks in a circuit whose output voltage changes when the crack propagates past a track. Data stored in memory can be remotely downloaded using Bluetooth™ technology to a PC.

  3. An Intelligent Sensor System for Monitoring Fatigue Damage in Welded Steel Components

    International Nuclear Information System (INIS)

    Fernandes, B.; Gaydecki, P.; Burdekin, F. Michael

    2005-01-01

    A system for monitoring fatigue damage in steel components is described. The sensor, a thin steel sheet with a pre-crack in it, is attached to the component. Its crack length increases by fatigue in service and is recorded using a microcontroller. Measurement is accomplished using conductive tracks in a circuit whose output voltage changes when the crack propagates past a track. Data stored in memory can be remotely downloaded using Bluetooth TM technology to a PC

  4. Mechanism of fatigue crack initiation in austenitic stainless steels in light water reactor environments

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.; Muscara, J.

    2003-01-01

    This paper examines the mechanism of fatigue crack initiation in austenitic stainless steels (SSs) in light water reactor (LWR) coolant environments. The effects of key material and loading variables on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The influence of reactor coolant environments on the formation and growth of fatigue cracks in polished smooth SS specimens is discussed. The results indicate that the fatigue lives of these steels are decreased primarily by the effects of the environment on the growth of cracks <200 μm and, to a lesser extent, on enhanced growth rates of longer cracks. The fracture morphology in the specimens has been characterized. Exploratory fatigue tests were conducted to study the effects of surface micropits or minor differences in the surface oxide on fatigue crack initiation. (author)

  5. Fatigue assessment by energy approach during tensile tests on AISI 304 steel

    Directory of Open Access Journals (Sweden)

    A. Risitano

    2017-01-01

    Full Text Available Estimation of the fatigue limit for steel ductile materials using non-destructive methods is a topic of great interest to researchers today. In recent years, the method adopted has implemented infrared sensors to detect the surface temperature and correlate it with the fatigue limit. In previous paper, a new energy approach was proposed to investigate the fatigue limit during tensile test. The numerical procedure proposed by Chrysochoos is adopted to clean infrared images and applied to analyse the surface heat sources during tensile test. AISI 304 specimens with rectangular cross-sections are tested. Moreover fatigue tests at increasing loads were carried out on steel by a stepwise succession, applied to the same specimen, for applying the thermographic method. The predictions of the fatigue limit, obtained by the analysis of the energy evolution during the static tests, were compared with the predictions obtained applying the thermographic method during fatigue tests.

  6. The Study on Environmental Fatigue Behavior of Low Alloy Steel and Stainless Steel Pipes Using the Simplified Plant Transients

    International Nuclear Information System (INIS)

    Yoo, One; Song, M. S.; Kim, I. Y.; Park, S. H.; Lee, B. S.

    2010-01-01

    Nuclear components categorized as ASME Code Class 1 shall be evaluated for the fatigue and satisfy the fatigue acceptance criteria, CUF(cumulative usage factor) < 1 in accordance with ASME Code. However, recent studies have shown the fatigue evaluation procedure may not give conservative results when the components operate in the water environment. NRC issued Regulatory Guide 1.207 which enforces the new fatigue evaluation method or Fen(environmental fatigue correction factor) method to nuclear plants to be newly constructed. This paper describes the characteristics of the behavior of low alloy and austenitic stainless steel straight pipe related to environmental fatigue, which are obtained by using the method suggested by Regulatory Guide 1.207 and simplified plant transients

  7. Low cycle fatigue behavior of Sanicro25 steel at room and at elevated temperature

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Petráš, Roman; Heczko, Milan; Kuběna, Ivo; Kruml, Tomáš; Chai, G.

    2014-01-01

    Roč. 615, OKT (2014), s. 175-182 ISSN 0921-5093 R&D Projects: GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : Sanicro 25 steel * Cyclic plasticity * Dislocation structure * Fatigue life * Effect of temperature Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.567, year: 2014

  8. Fatigue strength of repaired cracks in welded connections made of very high strength steels

    NARCIS (Netherlands)

    Akyel, A.

    2017-01-01

    For cyclically loaded structures, fatigue design becomes one of the important design criteria. The state of art shows that with modification of the conventional structural design methodology, the use of very high strength steels may have a positive effect on fatigue strength of welded connections.

  9. The effect of low temperatures on the fatigue of high-strength structural grade steels

    NARCIS (Netherlands)

    Walters, C.L.

    2014-01-01

    It is well-known that for fracture, ferritic steels undergo a sudden transition from ductile behavior at higher temperatures to brittle cleavage failure at lower temperatures. However, this phenomenon has not received much attention in the literature on fatigue. The so-called Fatigue Ductile-Brittle

  10. Investigation of thermal fatigue of chromium-molybdenum steels, used for calcining and agglomeration constructions

    International Nuclear Information System (INIS)

    Sinyavskij, D.P.; Gorkalo, A.P.

    1979-01-01

    The technique for investigating thermal fatigue of materials is described. The data on sample stress deformed state and current temperature values are taken from the local volume of the material studied. Results of investigating thermal fatigue of the 15KhMl and 20KhMl steels are presented

  11. Effect of ratchet strain on fatigue and creep–fatigue strength of Mod.9Cr–1Mo steel

    International Nuclear Information System (INIS)

    Ando, Masanori; Isobe, Nobuhiro; Kikuchi, Koichi; Enuma, Yasuhiro

    2012-01-01

    Highlights: ► Uniaxial fatigue and creep–fatigue tests with superimposed strain were performed. ► Variety of superimposed strain were applied as ratchet strain in the tests. ► Effect of superimposed strain on fatigue and creep–fatigue life is negligible. ► A cyclic softening character reducing the effect of superimposed strain. - Abstract: The effect of ratcheting deformation on fatigue and creep–fatigue life in Mod.9Cr–1Mo steel was investigated. Uniaxial fatigue and creep–fatigue testing with superimposed strain were performed to evaluate the effect of ratcheting deformation on the failure cycle. In a series of tests, a specific amount of superimposed strain was accumulated in each cycle. The accumulated strain as ratcheting deformation, cycles to reach the accumulated strain, and test temperatures were varied in the tests. In the fatigue tests with superimposed strain at 550 °C, slight reductions of failure lives were observed. All of the numbers of cycles to failure in the fatigue tests with superimposed strain were within a factor of 1.5 of that of the fatigue test without superimposed strain at 550 °C. The apparent relationship between failure cycles and testing parameters was not observed. In fatigue tests with superimposed strain at 550 °C, maximum mean stress was insignificant and generated in early cycles because Mod.9Cr–1Mo steel exhibits cyclic softening characteristics. It was assumed that suppression of mean stress generation by cyclic softening reduces the effect of ratcheting strain. Conversely, failure lives were increased by accumulated strain in the test conducted at 450 °C because of stress–strain hysteresis loop shrinkage caused by cyclic softening induced by the accumulated strain. In the creep–fatigue tests with superimposed strain, test results indicated that the accumulated stain was negligible. It was concluded that the effect of ratcheting deformation on fatigue and creep–fatigue life is negligible as long

  12. Effect of metallurgical variables on the austenite stability in fatigued AISI 304 type steels

    Czech Academy of Sciences Publication Activity Database

    Man, Jiří; Smaga, M.; Kuběna, Ivo; Eifler, D.; Polák, Jaroslav

    2017-01-01

    Roč. 185, NOV (2017), s. 139-159 ISSN 0013-7944. [XVIII International Colloquium Mechanical Fatigue of Metals. Gijón, 05.11.2016-07.11.2016] R&D Projects: GA ČR GA13-32665S Institutional support: RVO:68081723 Keywords : Austenitic stainless steel * Deformation induced martensite * Color metallography * Chemical banding * Low cycle fatigue Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering , reliability analysis Impact factor: 2.151, year: 2016

  13. Fatigue cracks in Eurofer 97 steel: Part I. Nucleation and small crack growth kinetics

    Czech Academy of Sciences Publication Activity Database

    Kruml, Tomáš; Polák, Jaroslav

    2011-01-01

    Roč. 412, 1 (2011), s. 2-6 ISSN 0022-3115 R&D Projects: GA ČR GA106/09/1954; GA ČR GA101/09/0867 Institutional research plan: CEZ:AV0Z20410507 Keywords : ferritic-martensitic steel * low cycle fatigue * small crack growth * fatigue life prediction Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.052, year: 2011

  14. Fatigue behavior of Type 316 stainless steel following neutron irradiation inducing helium

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Liu, K.C.

    1980-01-01

    Since a tokamak reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially in the first wall and blanket. There has been limited work on fatigue in irradiated alloys but none on irradiated materials containing significant amounts of irradiation-induced helium. To provide scoping data and to study the effects of irradiation on fatigue behavior, 20%-cold-worked type 316 stainless steel from the MFE reference heat was studied

  15. Influence of shear cutting parameters on the fatigue behavior of a dual-phase steel

    Science.gov (United States)

    Paetzold, I.; Dittmann, F.; Feistle, M.; Golle, R.; Haefele, P.; Hoffmann, H.; Volk, W.

    2017-09-01

    The influence of the edge condition of car body and chassis components made of steel sheet on fatigue behavior under dynamic loading presents a major challenge for automotive manufacturers and suppliers. The calculated lifetime is based on material data determined by the fatigue testing of specimens with polished edges. Prototype components are often manufactured by milling or laser cutting, whereby in practice, the series components are produced by shear cutting due to its cost-efficiency. Since the fatigue crack in such components usually starts from a shear cut edge, the calculated and experimental determined lifetime will vary due to the different conditions at the shear cut edges. Therefore, the material data determined with polished edges can result in a non-conservative component design. The aim of this study is to understand the relationship between the shear cutting process and the fatigue behavior of a dual-phase steel sheet. The geometry of the shear cut edge as well as the depth and degree of work hardening in the shear affected zone can be adjusted by using specific shear cutting parameters, such as die clearance and cutting edge radius. Stress-controlled fatigue tests of unnotched specimens were carried out to compare the fatigue behavior of different edge conditions. By evaluating the results of the fatigue experiments, influential shear cutting parameters on fatigue behavior were identified. It was possible to assess investigated shear cutting strategies regarding the fatigue behavior of a high-strength steel DP800.

  16. The temperature dependence and environmental enhancement mechanism of fatigue crack growth rates of A 351-CF8A cast stainless steel in LWR environment

    International Nuclear Information System (INIS)

    Cullen, W.H.; Haenninen, H.; Toerroenen, K.; Kemppainen, M.

    1984-01-01

    The fatigue crack growth rates for A 351-CF8A cast stainless steel were determined over a range of temperatures from 93 degC to 338 degC (200 degF to 640 degF). The waveform was 17 mHz sinusoidal and the load ratio was 0.2. The environment was borated and lithiated water with a dissolved oxygen content of approximately 1 ppb. The results show an easily measurable (factors of 2 to 8) increase in crack growth rates due to the environment. However, these rates are well within the known band of results for low-alloy pressure vessel and low-carbon piping steels in LWR environments. An extensive fractographic investigation shows fatigue fracture surfaces consisting of brittle morphology. This fracture morphology is similar to that of stress corrosion cracking of stainless steels, suggesting that there is a distinctive environmental assistance mechanism resulting in the increased crack growth rates. (author)

  17. Tensile and high cycle fatigue behaviors of high-Mn steels at 298 and 110 K

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Wongyu; Jeong, Daeho; Sung, Hyokyung; Kim, Sangshik, E-mail: sang@gnu.ac.kr

    2017-02-15

    Tensile and high cycle fatigue behaviors of high-Mn austenitic steels, including 25Mn, 25Mn0.2Al, 25Mn0.5Cu, 24Mn4Cr, 22Mn3Cr and 16Mn2Al specimens, were investigated at 298 and 110 K. Depending on the alloying elements, tensile ductility of high-Mn steels either increased or decreased with decreasing temperature from 298 to 110 K. Reasonable correlation between the tendency for martensitic tranformation, the critical twinning stress and the percent change in tensile elongation suggested that tensile deformation of high-Mn steels was strongly influenced by SFE determining TRIP and TWIP effects. Tensile strength was the most important parameter in determining the resistance to high cycle fatigue of high-Mn steels with an exceptional work hardening capability at room and cryogenic temperatures. The fatigue crack nucleation mechanism in high-Mn steels did not vary with decreasing tempertature, except Cr-added specimens with grain boundary cracking at 298 K and slip band cracking at 110 K. The EBSD (electron backscatter diffraction) analyses suggested that the deformation mechanism under fatigue loading was significantly different from tensile deformation which could be affected by TRIP and TWIP effects. - Highlights: •The resistances to HCF of various high-Mn steels were measured. •The variables affecting tensile and HCF behaviors of high-Mn steels were assessed. •The relationship between tensile and the HCF behaviors of high-Mn steels was established.

  18. Experimental verification of the statistical theories of scaling factor effect in fatigue fracture of steel

    International Nuclear Information System (INIS)

    Svistun, R.P.; Babej, Yu.I.; Tkachenko, N.N.

    1976-01-01

    Statistical theories of the scale effect in the fatigue failure of 40KH18N9T, 10 and 20 steels have been verified. The theories are shown to be not invariably suitable for a satisfactory exlanation of the fatigue strength of the samples with respect to their dimensions. One of the main reasons for displaying the scale effect in the process of steel fatigue is the sample self-heating, i.e. a temperature factor which in many cases overlaps a statistical one

  19. Experimental verification of the statistical theories of scaling factor effect in fatigue fracture of steel

    Energy Technology Data Exchange (ETDEWEB)

    Svistun, R P; Babei, Yu I; Tkachenko, N N [AN Ukrainskoj SSR, Lvov. Fiziko-Mekhanicheskij Inst.; L' vovskij Lesotekhnicheskij Inst. (Ukrainian SSR))

    1976-01-01

    Statistical theories of the scale effect in the fatigue failure of 40KH18N9T, 10 and 20 steels have been verified. The theories are shown to be not invariably suitable for a satisfactory exlanation of the fatigue strength of the samples with respect to their dimensions. One of the main reasons for displaying the scale effect in the process of steel fatigue is the sample self-heating, i.e. a temperature factor which in many cases overlaps a statistical one.

  20. EVALUATION OF METHODS FOR ESTIMATING FATIGUE PROPERTIES APPLIED TO STAINLESS STEELS AND ALUMINUM ALLOYS

    Directory of Open Access Journals (Sweden)

    Taylor Mac Intyer Fonseca Junior

    2013-12-01

    Full Text Available This work evaluate seven estimation methods of fatigue properties applied to stainless steels and aluminum alloys. Experimental strain-life curves are compared to the estimations obtained by each method. After applying seven different estimation methods at 14 material conditions, it was found that fatigue life can be estimated with good accuracy only by the Bäumel-Seeger method for the martensitic stainless steel tempered between 300°C and 500°C. The differences between mechanical behavior during monotonic and cyclic loading are probably the reason for the absence of a reliable method for estimation of fatigue behavior from monotonic properties for a group of materials.

  1. The research of axial corrosion fatigue on 10Ni3CrMoV steel

    Science.gov (United States)

    Xie, Xing; Yi, Hong; Xu, Jian; Xie, Kun

    2017-09-01

    Fatigue life had been studied with 10CrNi3MoV steel at different load ratios and in different environmental medias. The microstructure and micro-topography had been observed and analyzed by means of SEM, EDS and TEM. Our findings indicated that, the fatigue life of 10Ni3CrMoV steel in seawater was shorter than in air, the difference in longevity was larger with the decreasing of axis stress. Corrosion pits had a great influence on corrosion fatigue life.

  2. Influence of coatings on the corrosion fatigue behaviour on 13% chromium steel

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt-Thomas, K G; Meisel, H; Sessler, W

    1986-01-01

    The influence of coatings on the corrosion fatigue behaviour of 13% chromium steel has been studied. There have been selected different coating systems: Barrier coating (enamel), diffusion coatings, (aluminizing, chromizing) and anodic coating, (aluminium, zinc, tin, cadmium). The corrosion fatigue limits of coated with uncoated specimens in neutral NaCl-solution are compared. Salt-concentrations were 0,01 and 22% (=0,38 M) NaCl at 80/sup 0/C and 150/sup 0/C. The tests were carried out with alternating tensions and a constant frequency of 50 Hz. Only the use of anodic coatings improved the corrosion fatigue behaviour of the chromium steel.

  3. Microscopic examination of crack growth in a pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Isacsson, M.; Narstroem, T. [Royal Inst. of Tech., Stockholm (Sweden)

    1997-01-01

    A fairly systematic microscopic study concerning ductile and ductile-brittle crack growth in the A508B pressure vessel steel has been performed. The main method of investigation was to subject fracture mechanics specimens (sub-sized three point bend specimens) to predetermined load levels corresponding to different amounts of ductile crack extension. The specimens were then cut perpendicularly to the plane of the crack and the area in front of the crack was examined in a SEM. The object of these examinations was to determine if newly encountered computational results could be correlated to crack extension characteristics and to study whether the mechanism of ductile growth was of the void growth type or of the fast shear mechanism. This is important for further numerical modelling of the process. Both the original material and a specially heat treated piece were investigated. The heat treatment was performed in order to raise the transition temperature to about 60 deg C with the object to provide a more convenient testing situation. Charpy V tests were performed for the specially heat treated material to obtain the temperature dependence of the toughness. This was also studied by performing fracture toughness determination on the same type of specimens as were used for the microscopic study. The heat treatment used fulfilled the above purpose and the microscopic studies provide a good understanding of the micro mechanisms operating in the ductile fracture process for this material. 19 refs, 8 figs, 3 tabs.

  4. Microscopic examination of crack growth in a pressure vessel steel

    International Nuclear Information System (INIS)

    Isacsson, M.; Narstroem, T.

    1997-01-01

    A fairly systematic microscopic study concerning ductile and ductile-brittle crack growth in the A508B pressure vessel steel has been performed. The main method of investigation was to subject fracture mechanics specimens (sub-sized three point bend specimens) to predetermined load levels corresponding to different amounts of ductile crack extension. The specimens were then cut perpendicularly to the plane of the crack and the area in front of the crack was examined in a SEM. The object of these examinations was to determine if newly encountered computational results could be correlated to crack extension characteristics and to study whether the mechanism of ductile growth was of the void growth type or of the fast shear mechanism. This is important for further numerical modelling of the process. Both the original material and a specially heat treated piece were investigated. The heat treatment was performed in order to raise the transition temperature to about 60 deg C with the object to provide a more convenient testing situation. Charpy V tests were performed for the specially heat treated material to obtain the temperature dependence of the toughness. This was also studied by performing fracture toughness determination on the same type of specimens as were used for the microscopic study. The heat treatment used fulfilled the above purpose and the microscopic studies provide a good understanding of the micro mechanisms operating in the ductile fracture process for this material

  5. Kinetics of annealing of irradiated surveillance pressure vessel steel

    International Nuclear Information System (INIS)

    Harvey, D.J.; Wechsler, M.S.

    1982-01-01

    Indentation hardness measurements as a function of annealing were made on broken halves of Charpy impact surveillance samples. The samples had been irradiated in commercial power reactors to a neutron fluence of approximately 1 x 10 18 neutrons per cm 2 , E > 1 MeV, at a temperature of about 300 0 C (570 0 F). Results are reported for the weld metal, which showed greater radiation hardening than the base plate or heat-affected zone material. Isochronal and isothermal anneals were conducted on the irradiated surveillance samples and on unirradiated control samples. No hardness changes upon annealing occurred for the control samples. The recovery in hardness for the irradiated samples took place mostly between 400 and 500 0 C. Based on the Meechan-Brinkman method of analysis, the activation energy for annealing was found to be 0.60 +- 0.06 eV. According to computer simulation calculations of Beeler, the activation energy for migration of vacancies in alpha iron is about 0.67 eV. Therefore, the results of this preliminary study appear to be consistent with a mechanism of annealing of radiation damage in pressure vessel steels based on the migration of radiation-produced lattice vacancies

  6. Fatigue life evaluation method of austenitic stainless steel in PWR water

    International Nuclear Information System (INIS)

    Sakaguchi, Katsumi; Nomura, Yuichiro; Suzuki, Shigeki; Kanasaki, Hiroshi; Higuchi, Makoto

    2006-09-01

    It is known that the fatigue life in elevated temperature water is substantially reduced compared with that in the air. The fatigue life reduction has been investigated experimentally in EFT project of Japan Nuclear Energy Safety Organization (JNES) to evaluate the environmental effect on fatigue life. Many tests have been done for carbon, low alloy, stainless steels and nickel-based alloy under the various conditions. In this paper, the results of the stainless steel in simulated PWR water environments were reported. Fatigue life tests in simulated PWR environments were carried out and the effect of key parameters on fatigue life reduction was examined. The materials used in this study were base and weld metal of austenitic stainless steel SS316, weld metal of SS304 and the base and aged metal of the duplex stainless steel SCS14A. In order to evaluate the effects of stain amplitude, strain rate, strain ratio, temperature, aging, water flow rate and strain holding time, many fatigue tests were examined. In transient condition in an actual plant, however, such parameters as temperature and strain rate are not constant. In order to evaluate fatigue damage in actual plant on the basis of experimental results under constant temperature and strain rate condition, the modified rate approach method was developed. Various kinds of transient have to be taken into account of in actual plant fatigue evaluation, and stress cycle of several ranges of amplitude has to be considered in assessing damage from fatigue. Generally, cumulative usage factor is applied in this type of evaluation. In this study, in order to confirm the applicability of modified rate approach method together with cumulative usage factor, fatigue tests were carried out by combining stress cycle blocks of different strain amplitude levels, in which strain rate changes in response to temperature in a simulated PWR water environment. Consequently, fatigue life could be evaluated with an accuracy of factor of 3

  7. Current Status of Development of High Nickel Low Alloy Steels for Commercial Reactor Pressure Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Chul; Lee, B. S.; Park, S. G.; Lee, K. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-12-15

    SA508 Gr.3 Mn-Mo-Ni low alloy steels have been used for nuclear reactor pressure vessel steels up to now. Currently, the design goal of nuclear power plant is focusing at larger capacity and longer lifetime. Requirements of much bigger pressure vessels may cause critical problems in the manufacturing stage as well as for the welding stage. Application of higher strength steel may be required to overcome the technical problems. It is known that a higher strength and fracture toughness of low alloy steels such as SA508 Gr.4N low alloy steel could be achieved by increasing the Ni and Cr contents. Therefore, SA508 Gr.4N low alloy steel is very attractive as eligible RPV steel for the next generation PWR systems. In this report, we propose the possibility of SA508 Gr.4N low alloy steel for an application of next generation commercial RPV, based on the literature research result about development history of the RPV steels and SA508 specification. In addition, we have surveyed the research result of HSLA(High Strength Low Alloy steel), which has similar chemical compositions with SA508 Gr.4N, to understand the problems and the way of improvement of SA508 Gr.4N low alloy steel. And also, we have investigated eastern RPV steel(WWER-1000), which has higher Ni contents compared to western RPV steel.

  8. Historical summary of the heavy-section steel technology program and some related activities in light-water reactor pressure vessel safety research

    International Nuclear Information System (INIS)

    Whitman, G.D.

    1986-03-01

    The accomplishments of the Heavy-Section Steel Technology Program and other programs having a close relationship to the development of information used in the assessment of light-water reactor pressure vessel integrity are reviewed. The early Pressure Vessel Research Committee planning, the principals contributing to program formulation, the role of the US Atomic Energy Commission, and the developments under the US Nuclear Regulatory Commission sponsorship are identified. The need for major research and development accomplishments in fracture mechanics, heavy-section steel procurement, materials properties, irradiation effects, fatigue crack growth, and structural testing are summarized. The impact of program results on regulatory issues and the development of data used in the preparation of codes, standards, and guides are discussed. Continuing activities and recommendations for future research and development in support of pressure vessel integrity assessments are presented

  9. Fatigue crack retardation of high strength steel in saltwater

    International Nuclear Information System (INIS)

    Tokaji, K.; Ando, Z.; Imai, T.; Kojima, T.

    1983-01-01

    A high strength steel was studied in 3 percent saltwater to investigate the effects of a corrosive environment and sheer thickness on fatigue crack propagation behavior following the application of a single tensile overload. Experiments were carried out under sinusoidally varying loads at a load ratio of 0 and frequency of 10 H /SUB z/ . A single tensile overload was found to cause delayed retardation, and the crack propagation rate at first increased, followed by fairly rapid decrease to a minimum value and then increased gradually to its steady-state value, just as it did in air. The overload affected zone size and the retardation cycles increased with decreasing sheet thickness, just as they did in air. However, the zone size and the cycles were larger in 3 percent saltwater than in air. Since the crack propagation rates through the overload affected zone were not affected by the test environment, the longer retardation cycles in 3 percent saltwater were attributed to an enlargement of the overload affected zone size. The crack propagation behavior following the application of a single tensile overload in 3 percent saltwater was well explained by the crack closure concept

  10. Fatigue properties of X80 pipeline steels with ferrite/bainite dual-phase microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zuo-peng [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Qiao, Gui-ying [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Key Lab of Applied Chemistry of Hebei Province and School of Environment and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Tang, Lei [Key Lab of Applied Chemistry of Hebei Province and School of Environment and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Zhu, Hong-wei; Liao, Bo [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China); Xiao, Fu-ren, E-mail: frxiao@ysu.edu.cn [Key Lab of Metastable Materials Science & Technology and College of Materials Science & Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-03-07

    Fatigue properties are important parameters for the safety design and security evaluation of gas transmission pipelines. In this work, the fatigue life at different stresses of full-thickness X80 pipeline steel plates with a ferrite/bainite dual-phase microstructure was investigated using a MTS servo-hydraulic universal testing machine; the fatigue crack propagation rate was examined with CT specimens by using an INSTRON 8874 testing machine. Results indicate that fatigue life increases as maximum stress decreases; as the maximum stress decreases to the maximum operating stress (440 MPa), the fatigue life is approximately 4.2×10{sup 5} cycles. The fatigue crack of the full-thickness fatigue life specimens is generated at the surface of rolled steel plates and then the crack propagates and grows inward until a fracture is formed. During fatigue crack growth, a transitional turning point appears in the curve of da/dN with ΔK in the Paris region. The transitional turning point that divides the Paris region to two stages is approximately ΔK≅30 MPa m{sup 1/2}. The change in the growth rate (da/dN) is related to the variation of the crack path and in the fracture mode because of the possible microstructural sensitivity of fatigue crack propagation behavior. This study also discussed the effect of duple phase ferrite/bainite microstructure on fatigue crack initiation and propagation.

  11. Fatigue properties of X80 pipeline steels with ferrite/bainite dual-phase microstructure

    International Nuclear Information System (INIS)

    Zhao, Zuo-peng; Qiao, Gui-ying; Tang, Lei; Zhu, Hong-wei; Liao, Bo; Xiao, Fu-ren

    2016-01-01

    Fatigue properties are important parameters for the safety design and security evaluation of gas transmission pipelines. In this work, the fatigue life at different stresses of full-thickness X80 pipeline steel plates with a ferrite/bainite dual-phase microstructure was investigated using a MTS servo-hydraulic universal testing machine; the fatigue crack propagation rate was examined with CT specimens by using an INSTRON 8874 testing machine. Results indicate that fatigue life increases as maximum stress decreases; as the maximum stress decreases to the maximum operating stress (440 MPa), the fatigue life is approximately 4.2×10"5 cycles. The fatigue crack of the full-thickness fatigue life specimens is generated at the surface of rolled steel plates and then the crack propagates and grows inward until a fracture is formed. During fatigue crack growth, a transitional turning point appears in the curve of da/dN with ΔK in the Paris region. The transitional turning point that divides the Paris region to two stages is approximately ΔK≅30 MPa m"1"/"2. The change in the growth rate (da/dN) is related to the variation of the crack path and in the fracture mode because of the possible microstructural sensitivity of fatigue crack propagation behavior. This study also discussed the effect of duple phase ferrite/bainite microstructure on fatigue crack initiation and propagation.

  12. Influence of laser cutting on the fatigue limit of two high strength steels

    International Nuclear Information System (INIS)

    Mateo, Antonio; Fargas, Gemma; Calvo, Jessica; Roa, Joan Josep

    2015-01-01

    Laser cutting is widely used in the metal industry, particularly when components of high strength steel sheets are produced. However, the roughness of cut edges produced by laser differs from that obtained by other methods, such as mechanical blanking, and this fact influences the fatigue performance. In the present investigation, specimens of two grades of high strength austenitic steels, i.e. AISI 301LN and TWIP17Mn, were cut by laser and tested in the high cycle fatigue regime to determine their corresponding fatigue limits. A series of fatigue specimens were tested without polishing and other series after a careful polishing of the cut edges, in order to assess the influence of the cut edges condition. Results indicate a significant influence of the edge roughness, more distinctive for AISI 301LN than for TWIP steel.

  13. Influence of laser cutting on the fatigue limit of two high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Mateo, Antonio; Fargas, Gemma; Calvo, Jessica; Roa, Joan Josep [Univ. Politecnica de Catalunya, Barcelona (Spain). Dept. of Materials Science and Metallurgical Engineering

    2015-02-01

    Laser cutting is widely used in the metal industry, particularly when components of high strength steel sheets are produced. However, the roughness of cut edges produced by laser differs from that obtained by other methods, such as mechanical blanking, and this fact influences the fatigue performance. In the present investigation, specimens of two grades of high strength austenitic steels, i.e. AISI 301LN and TWIP17Mn, were cut by laser and tested in the high cycle fatigue regime to determine their corresponding fatigue limits. A series of fatigue specimens were tested without polishing and other series after a careful polishing of the cut edges, in order to assess the influence of the cut edges condition. Results indicate a significant influence of the edge roughness, more distinctive for AISI 301LN than for TWIP steel.

  14. Sensitivity Analysis of Fatigue Crack Growth Model for API Steels in Gaseous Hydrogen.

    Science.gov (United States)

    Amaro, Robert L; Rustagi, Neha; Drexler, Elizabeth S; Slifka, Andrew J

    2014-01-01

    A model to predict fatigue crack growth of API pipeline steels in high pressure gaseous hydrogen has been developed and is presented elsewhere. The model currently has several parameters that must be calibrated for each pipeline steel of interest. This work provides a sensitivity analysis of the model parameters in order to provide (a) insight to the underlying mathematical and mechanistic aspects of the model, and (b) guidance for model calibration of other API steels.

  15. Effect of microstructure on low cycle fatigue properties of ODS steels

    Energy Technology Data Exchange (ETDEWEB)

    Kubena, Ivo, E-mail: kubena@ipm.cz [IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, Brno (Czech Republic); Fournier, Benjamin [CEA/DEN/DANS/DMN/SRMA, Bat. 453, 91191 Gif-sur-Yvette Cedex (France); Kruml, Tomas [CEITEC IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, Brno (Czech Republic)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Three various ODS steels are studied and compared. Black-Right-Pointing-Pointer Low cycle fatigue data at RT, 650 Degree-Sign C and 750 Degree-Sign C are given. Black-Right-Pointing-Pointer Microstructural characterization. Black-Right-Pointing-Pointer Detailed discussion of strengthening mechanisms. - Abstract: Low cycle fatigue properties at room temperature, 650 Degree-Sign C and 750 Degree-Sign C of three high chromium steels (9%Cr ferritic-martensitic and two 14%Cr ferritic steels) strengthened by oxide dispersion were studied and compared. Cyclic softening/hardening curves, cyclic deformation curves, S-N curves and Coffin-Manson curves are presented together with microstructural observations. Differences in cyclic response, stress level and fatigue life are attributed to differences in the matrix microstructure. The oxide particles stabilize the cyclic response, even if cyclic softening is detected for some experimental conditions. The strength of these steels is discussed in terms of strengthening mechanisms such as grain size effect, particle-dislocations interaction and dislocation density. Comparing three different ODS steels offers an opportunity to tests the contribution of individual mechanisms to the cyclic strength. The reduction of fatigue life in one of the ferritic steels is explained by the presence of large grains, facilitating the fatigue crack nucleation and the early growth.

  16. Study on creep-fatigue evaluation of chrome-molybdenum steel

    International Nuclear Information System (INIS)

    Aoto, Kazumi; Wada, Yusaku

    1993-01-01

    Though chrome-molybdenum steel has quite different basic material properties from austenitic stainless steel, the life fraction rule based on an advanced ductility exhaustion theory proposed for SUS304 is able to give proper prediction for creep-fatigue life of chrome-molybdenum steel. The applicability of the present evaluation method to chrome-molybdenum steel is validated by both mechanical study and micro-structural observation. The mechanism of creep-fatigue failure of Mod.9Cr-1Mo(NT) is one of the most controversial subjects among researchers. However, it is clarified in this report that creep-fatigue damage of this material under actual loading conditions is dominated by creep-cavitation of grain boundaries as same way as that of austenitic stainless steel. Furthermore, for the life reduction of low cycle fatigue of chrome-molybdenum steel with compression-side strain hold, both effects of mean stress and oxide-wedge are denied and it is insisted that the acceleration of fatigue-crack propagation is occurred by oxide-progress location and its thickness. (author)

  17. Evaluation of long term creep-fatigue life for type 304 stainless steel

    International Nuclear Information System (INIS)

    Kawasaki, Hirotsugu; Ueno, Fumiyoshi; Aoto, Kazumi; Ichimiya, Masakazu; Wada, Yusaku

    1992-01-01

    The long term creep-fatigue life of type 304 stainless steel was evaluated by the creep-fatigue life prediction method based on a linear damage fraction rule. The displacement controlled creep-fatigue tests were carried out, and the time to failure of longer than 10000 hours was obtained. The creep damage of long term creep-fatigue was evaluated by taking into account the stress relaxation behavior with elastic follow-up during the hold period. The relationship between life reduction of creep-fatigue and fracture mode was provided by the creep cavity growth. The results of this study are summarized as follows; (1) The long term creep-fatigue data can be reasonably evaluated by the present method. The predicted lives were within a factor of 3 of the observed ones. (2) The present method provides the capability to predict the long term creep-fatigue life at lower temperatures as well as that at the creep dominant temperature. (3) The value of creep damage for the long term creep-fatigue data increased by elastic follow-up. The creep-fatigue damage diagram intercepted between 0.3 and 1 can represent the observed creep-fatigue damages. (4) The cavity growth depends on the hold time. The fracture of long term creep-fatigue is caused by the intergranular cavity growth. The intergranular fracture of creep-fatigue is initiated by the cavity growth and followed by the microcrack propagation along grain boundaries starting from creep cavities. (author)

  18. Influence of non-metallic second phases on fatigue behaviour of high strength steel components

    International Nuclear Information System (INIS)

    Gonzalez, L.; Elvira, R.; Garcia de Andoin, A.; Pizarro, R.; Bertrand, C.

    2005-01-01

    To assess the real effect of the inclusion type on fatigue life of ultra clean high strength steels mechanical components made of 100Cr6 steel were fatigue tested and fracture surfaces analysed to determine the origin of fatigue cracks.Two heats proceedings from different steelmaking routes were taken for the tests. The material were forged into ring shape components which were fatigue tested under compression-compression loads. Failures were analysed by SFEM (Scanning field Emission Microscopy), proving that most of failures at high loads were originated by manganese sulphides of small size (10-70 micros), while less than 40% of all fatigue cracks due to inclusions were caused by titanium carbonitrides and hard oxides. It has been demonstrated that once number and size of hard inclusions have been reduced, the hazardous effect of oxides and carbonitrides on the fatigue life decreases also. However, softer inclusions as manganese sulphides, currently considered as less hazardous, play a more relevant role as direct cause of fatigue failure and they should be taken into account in a deeper way in order to balance both machinability and fatigue life requirements in high strength steel components. (Author) 11 refs

  19. Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

    Directory of Open Access Journals (Sweden)

    Oh M.C.

    2015-06-01

    Full Text Available The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

  20. Environmental fatigue behaviors of wrought and cast stainless steels in 310degC deoxygenated water

    International Nuclear Information System (INIS)

    Cho, Pyung-Yeon; Jang, Hun; Jang, Changheui; Jeong, Ill-Seok; Lee, Jae-Gon

    2009-01-01

    Environmental fatigue behaviors of wrought type 316LN stainless steel and cast CF8M stainless steel were investigated. Low cycle fatigue tests were performed in a 310degC deoxygenated water environment at a strain rate of 0.04%/s with various strain amplitudes. It was shown that the low cycle fatigue life of CF8M was slightly longer than that of 316LN. To understand the causes of the difference, fracture surface was observed and material factors like microstructure, mechanical properties, and chemical compositions of both materials were analyzed. In a duplex microstructure of CF8M, the fatigue crack growth was affected by barrier role of ferrite phase and acceleration role of microvoids in ferrite phase. Test results indicate that the former is greater than the latter, resulting in slower fatigue crack growth rate, or longer LCF lives in CF8M than in 316LN. (author)

  1. A proposal of parameter to predict biaxial fatigue life for CF8M cast stainless steels

    International Nuclear Information System (INIS)

    Park, Joong Cheul; Kwon, Jae Do

    2005-01-01

    Biaxial low cycle fatigue test was carried out to predict fatigue life under combined axial-torsional loading condition which is that of in-phase and out-of-phase for CF8M cast stainless steels. Fatemi Socie(FS) parameter which is based on critical plane approach is not only one of methods but also the best method that can predict fatigue life under biaxial loading condition. But the result showed that, biaxial fatigue life prediction by using FS parameter with several different parameters for the CF8M cast stainless steels is not conservative but best results. So in this present research, we proposed new fatigue life prediction parameter considering effective shear stress instead of FS parameter which considers the maximum normal stress acting on maximum shear strain and its effectiveness was verified

  2. Overview of research trends and problems on Cr-Mo low alloy steels for pressure vessel

    International Nuclear Information System (INIS)

    Chi, Byung Ha; Kim, Jeong Tae

    2000-01-01

    Cr-Mo low alloy steels have been used for a long time for pressure vessel due to its excellent corrosion resistance, high temperature strength and toughness. The paper reviewed the latest trends on material development and some problems on Cr-Mo low alloy steel for pressure vessel, such as elevated temperature strength, hardenability, synergetic effect between temper and hydrogen embrittlement, hydrogen attack and hydrogen induced disbonding of overlay weld-cladding

  3. Estimation of residual stresses in reactor pressure vessel steel specimens clad by stainless steel strip electrodes

    International Nuclear Information System (INIS)

    Schimmoeller, H.A.; Ruge, J.L.

    1978-01-01

    The equations to determine a two-dimensional state of residual stress in flat laminated plates are well known from an earlier work by one of the authors. The derivation of these equations leads to a linear, inhomogeneous system of Volterra's integral equations of the second kind. To ascertain the unknown residual stresses from these equations it is necessary to cut down the thickness of the test plate layer by layer. This results in two-dimensional deformation reactions in the rest of the test plate, which can be measured, e.g. by a strain gauge rosette applied to the opposite side of the plate. The above-mentioned stress analysis has been transferred to 86mm thick reactor pressure vessel steel specimens (Type 22NiMoCr 37, DIN-No. 1.6751, similar to ASTM A508, Class 2) double-run clad by austenitic stainless steel strip electrodes (first layer 24/13 Cr-Ni steel, second layer 21/10 Cr-Ni steel). The overall dimensions of the clad specimens investigated amounted to 200 x 200 x (86+4.5+4.5)mm. At the surface of the austenitic cladding there is a two-dimensional tensile normal stress state of about 200N/mm 2 parallel, and about 300N/mm 2 transverse, to the welding direction. The maximum tensile stress was 8mm below the interface (fusion line, material transition) in the parent material. The stress distributions of the specimens investigated, determined on the basis of the above-mentioned combined experimental mathematical procedure, are presented graphically for the as-welded (as-delivered) and annealed (600 0 C/12hr) conditions. (author)

  4. Heat affected zone and fatigue crack propagation behavior of high performance steel

    International Nuclear Information System (INIS)

    Choi, Sung Won; Kang, Dong Hwan; Kim, Tae Won; Lee, Jong Kwan

    2009-01-01

    The effect of heat affected zone in high performance steel on fatigue crack propagation behavior, which is related to the subsequent microstructure, was investigated. A modified Paris-Erdogan equation was presented for the analysis of fatigue crack propagation behavior corresponding to the heat affected zone conditions. Fatigue crack propagation tests under 0.3 stress ratio and 0.1 load frequency were conducted for both finegrained and coarse-grained heat affected zones, respectively. As shown in the results, much higher crack growth rate occurred in a relatively larger mean grain size material under the same stress intensity range of fatigue crack propagation process for the material.

  5. A study on the fatigue behavior of Steel Fiber Reinforced Concrete structures with initial cracks

    International Nuclear Information System (INIS)

    Chang, Dong-Il; Chai, Won-Kyu; Son, Young-Hyun; Park, Cheol-Woo

    1992-01-01

    Fatigue tests are performed in order to investigate the fatigue behavior of SFRC (Steel Fiber Reinforced Concrete) structures. Thirty SFRC beams are used in this test. The relationships between repeated loading cycle and mid-span deflection of the beams are observed under the three-point loading system. From the test results, the effects of the fiber content and the fiber aspect ratio on the concrete fatigue behavior were studied. According to the regression technique, some empirical formulae for predicting the fatigue strength of SFRC beams are also suggested. (author)

  6. Fatigue of welded joint in a stainless steel AISI 304 L

    International Nuclear Information System (INIS)

    Kuromoto, N.K.; Guimaraes, A.S.; Miranda, P.E.V. de

    1986-01-01

    The flexion fatigue behavior for the base metal and welded joint of an AISI 304 L stainless steel type, used in the Angra-1 reactor, was determined. An automatic welding process was used with improved procedures in order to assure better welding metallurgy. Fatigue tests samples reinforcements were done to allow the evaluation of metallurgical variables, specially the role played by delta ferrite. The resulting welded joint showed better fatigue life than the base metal. Delta ferrite was found to play an important role on the initiation and propagation processes of the fatigue cracks. (Author) [pt

  7. Fatigue hardening and softening studies on strain hardened 18-8 austenitic stainless steel

    International Nuclear Information System (INIS)

    Ramakrishna Prasad, C.; Vasudevan, R.

    1976-01-01

    Metals when subjected to fatigue harden or soften depending on their previous mechanical history. Annealed or mildly cold worked metals are known to harden while severely cold worked metals soften when subjected to fatigue loading. In the present work samples of austenitic 18-8 steel cold worked to 11% and 22% reduction in area were mounted in a vertical pulsator and fatigued in axial tension-compression. Clear cut effects were produced and it was noticed that these depended on the extent of cold work, the amplitude as well as the number of cycles of fatigue and mean stress if any. (orig.) [de

  8. Fatigue-crack propagation behavior of steels in vacuum, and implications for ASME Section 11 crack growth analyses

    International Nuclear Information System (INIS)

    James, L.A.

    1985-08-01

    Section XI of the ASME Boiler and Pressure Vessel Code provides rules for the analysis of structures for which cracks or crack-like flaws have been discovered during inservice inspection. The Code provides rules for the analysis of both surface flaws as well as flaws that are embedded within the wall of the pressure vessel. In the case of surface flaws, the Code provides fatigue crack growth rate relationships for typical nuclear pressure vessel steels (e.g., ASTM A508-2 and A533-B) cycled in water environments typical of those in light-water reactors (LWR). However, for the case of embedded cracks, the Code provides crack growth relationships based on results from specimens that were cycled in an elevated temperature air environment. Although these latter relationships are often referred to as applying to ''inert'' environments, the results of this paper will show that an elevated temperature air environment is anything but inert, and that use of such relationships can result in overly pessimistic estimates of fatigue-crack growth lifetimes of embedded cracks. The reason, of course, is that embedded cracks grow in an environment that is probably much closer to a vacuum than an air environment

  9. Fracture probability properties of pure and cantilever bending fatigue of STS304 steel

    International Nuclear Information System (INIS)

    Roh, Sung Kuk; Park, Dae Hyun; Jeong, Soon Uk

    2001-01-01

    Big accidents of flyings, vessel, subways, gas equipments, buildings and bridge happens frequently. Therefore many people are suffering harm of property. The destruction cause of marcaine components is almost accused by fatigue. This study is test for STS304 specimen using pure and cantilever bending state. Rounded and notched specimen including fracture surface investigation was comparatively experimented, fatigue life according to degree of surface finishing was examined. Fatigue fracture probability of notched canilever specimens were predicted by P-S-N curve, median rank and Weibull distribution. And at the relation with the rotational speed and stress, the fatigue life of the test specimen was higher at high speed than low speed

  10. The electrogas and electroslag multipass high speed welding of nuclear pressure vessel steels

    International Nuclear Information System (INIS)

    Eichhorn, F.; Hirsch, P.; Langenbahn, H.W.; Wubbels, B.

    1978-01-01

    High-speed electroslag and electrogas welding of 15 Mn Ni63 steel plates to achieve high strength and toughness joints for reactor pressure vessels are described. Mechanical testing of overheating-resistant, brittle fracture resistant low alloy steels is discussed. (UK)

  11. Thermal fatigue cracking of austenitic stainless steels; Fissuration en fatigue thermique des aciers inoxydables austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Fissolo, A

    2001-07-01

    This report deals with the thermal fatigue cracking of austenitic stainless steels as AISI 316 LN and 304 L. Such damage has been clearly observed for some components used in Fast Breeder reactors (FBR) and Pressure Water Reactor (PWR). In order to investigate thermal fatigue, quasi-structural specimen have been used. In this frame, facilities enforcing temperature variations similar to those found under the operation conditions have been progressively developed. As for components, loading results from impeded dilatation. In the SPLASH facility, the purpose was to establish accurate crack initiation conditions in order to check the relevance of the usual component design methodology. The tested specimen is continuously heated by the passage of an electrical DC current, and submitted to cyclic thermal down shock (up to 1000 deg C/s) by means of periodical spraying of water on two opposite specimen faces. The number of cycles to crack initiation N{sub i} is deduced from periodic examinations of the quenched surfaces, by means of optical microscopy. It is considered that initiation occurs when at least one 50{mu}m to 150{open_square}m long crack is observed. Additional SPLASH tests were performed for N >> N{sub i}, with a view to investigate the evolution of a surface multiple cracking network with the number of cycles N. The CYTHIA test was mainly developed for the purpose of assessing crack growth dynamics of one isolated crack in thermal fatigue conditions. Specimens consist of thick walled tubes with a 1 mm circular groove is spark-machined at the specimen centre. During the test, the external wall of the tube is periodically heated by using a HF induction coil (1 MHz), while its internal wall is permanently cooled by flowing water. Total crack growth is derived from post-mortem examinations, whereby the thermal fatigue final rupture surface is oxidized at the end of the test. The specimen is broken afterwards under mechanical fatigue at room temperature. All the

  12. Residual stresses in a weldment of pressure vessel steel

    International Nuclear Information System (INIS)

    Gott, K.E.

    1978-01-01

    A study was made of the distribution of residual stresses around a typical weld from a light water reactor pressure vessel by an X-ray double-exposure camera technique. So that the magnitude, sign, and distribution of the residual stresses were as similar as possible to those found in practice, a wide, full-thickness specimen of A533B Cl 1 steel containing a submerged-arc weld was stress-relief annealed. To obtain a three-dimensional distribution of the stresses the specimen was examined at different levels through the thickness. Following the removal of material by milling, the specimen surface was electropolished to free it from cold work. Corrections have been made to take into account specimen relaxation. To completely define the original stress system it is desirable also to measure the change in curvature on removing a layer of material. Unless this is done assumptions must be made which complicate the calculations unnecessarily. This became apparent after the experimental work was completed. In the centre of the plate the methods of correction which can be used are sensitive to errors in the measurements. The corrected results show that the dominant residual stress is perpendicular to the weld. It is positive at the surfaces and negative in the centre of the plate. The maximum value can reach the yield stress. The residual stresses in the weld metal can locally vary considerably: from 100 to 350N/mm 2 over a distance of 5mm. Such large variations have been found to coincide with the heat-affected zones of the individual weld runs. (author)

  13. Irradiation effects in low-alloy reactor pressure vessel steels (Heavy-Section Steel Technology program series 4 and 5)

    International Nuclear Information System (INIS)

    McGowan, J.J.; Nanstad, R.K.; Thoms, K.R.; Menke, B.H.

    1985-01-01

    This report presents studies on the irradiation effects in low-alloy reactor pressure vessel steels. The Fourth Heavy-Section Steel Technology (HSST) Irradiation Series, almost completed, was aimed at elastic-plastic and fully plastic fracture toughness of low-copper weldments (''current practice welds''). A typical nuclear pressure vessel plate steel was included for statistical purposes. The Fifth HSST Irradiation Series, now in progress, is aimed at determining the shape of the K/sub IR/ curve after significant radiation-induced shift of the transition temperatures. This series includes irradiated test specimens of thicknesses up to 100 mm and weldment compositions typical of early nuclear power reactor pressure vessel welds. 27 refs., 22 figs

  14. Frost fatigue and spring recovery of xylem vessels in three diffuse-porous trees in situ.

    Science.gov (United States)

    Christensen-Dalsgaard, Karen K; Tyree, Melvin T

    2014-05-01

    Frost has been shown to cause frost fatigue (reduced cavitation resistance) in branch segments in the lab. Here, we studied the change in cavitation resistance and percent loss of conductivity (PLC) from fall to spring over 2 consecutive years in three diffuse-porous species in situ. We used the cavitron technique to measure P25 , P50 and P90 (the xylem pressure causing a 25, 50 and 90% conductivity loss) and PLC and stained functioning vessels. Cavitation resistance was reduced by 64-87% (in terms of P50 ), depending on the species and year. P25 was impacted the most and P90 the least, changing the vulnerability curves from s- to r-shaped over the winter in all three species. The branches suffered an almost complete loss of conductivity, but frost fatigue did not necessarily occur concurrently with increases in PLC. In two species, there was a trade-off between conduit size and vulnerability. Spring recovery occurred by growth of new vessels, and in two species by partial refilling of embolized conduits. Although newly grown and functioning conduits appeared more vulnerable to cavitation than year-old vessels, cavitation resistance generally improved in spring, suggesting other mechanisms for partial frost fatigue repair. © 2013 John Wiley & Sons Ltd.

  15. Analyses of a steel containment vessel with an outer contact structure under severe internal overpressurization conditions

    International Nuclear Information System (INIS)

    Porter, V.L.

    1994-01-01

    Many Mark-I and Mark-II BWR plants are designed with a steel vessel as the primary containment. Typically, the steel containment vessel (SCV) is enclosed within a reinforced concrete shield building with only a small gap (74-90 mm) separating the two structures. This paper describes finite element analyses performed to evaluate the effects of contact and friction between a steel containment vessel and an outer contact structure when the containment vessel is subjected to large internal pressures. These computations were motivated by a joint program on containment integrity involving the Nuclear Power Engineering Corporation (NUPEC) of Japan, the US Nuclear Regulatory Commission (NRC), and Sandia National Laboratories for testing model containments. Under severe accident loading conditions, the steel containment vessel in a typical Mark-I or Mark-II plant may deform under internal pressurization such that it contacts the inner surface of a shield building wall. (Thermal expansion from increasing accident temperatures would also close the gap between the SCV and the shield building, but temperature effects are not considered in these analyses.) The amount and location of contact and the pressure at which it occurs all affect how the combined structure behaves. A preliminary finite element model has been developed to analyze a model of a typical steel containment vessel con-ling into contact with an outer structure. Both the steel containment vessel and the outer contact structure were modelled with axisymmetric shell finite elements. Of particular interest are the influence that the contact structure has on deformation and potential failure modes of the containment vessel. Furthermore, the coefficient of friction between the two structures was varied to study its effects on the behavior of the containment vessel and on the uplift loads transmitted to the contact structure. These analyses show that the material properties of an outer contact structure and the amount

  16. Research on Fatigue Damage of Compressor Blade Steel KMN-I Using Nonlinear Ultrasonic Testing

    Directory of Open Access Journals (Sweden)

    Pengfei Wang

    2017-01-01

    Full Text Available The fatigue damage of compressor blade steel KMN-I was investigated using nonlinear ultrasonic testing and the relation curve between the material nonlinearity parameter β and the fatigue life was obtained. The results showed that the nonlinearity parameter increased first and then decreased with the increase of the fatigue cycles. The microstructures were observed by scanning electron microscopy (SEM. It was found that some small defects like holes and pits appeared in the material matrix with the increase of the fatigue cycles, and the nonlinearity parameter increased correspondingly. The nonlinearity parameter reached the peak value when the microcracks initiated, and the nonlinearity parameter began to decrease when the microcracks further propagated to macrocracks. Therefore, it is proved that the nonlinearity parameter can be used to characterize the initiation of microcracks at the early stage of fatigue, and a method of evaluating the fatigue life of materials by nonlinear ultrasonic testing is proposed.

  17. Improvement of the fatigue strength of AISI 4140 steel by an ion nitriding process

    Energy Technology Data Exchange (ETDEWEB)

    Celik, A. [Atatuerk Univ., Erzurum (Turkey). Dept. of Mech. Eng.; Karadeniz, S. [Dokuz Eyluel Univ., Izmir (Turkey). Dept. of Mech. Eng.

    1995-06-01

    The influence of plasma nitriding on the fatigue behaviour of AISI 4140 low-alloy steel was investigated under varying process conditions of temperature (500-600 C), time (1-12 h), heat treatment before ion nitriding (quenched and tempered, normalized) and gas mixture (50% H{sub 2}-50% N{sub 2}). A rotating bending fatigue machine was used to determine the fatigue strength. It was found that the plasma nitriding improves the fatigue strength and increases the fatigue limit depending on the surface hardness of the case depth. The microstructure of surface and diffusion layers was examined by optical microscopy. The fracture surface of specimens and the origin of fatigue cracks were observed by scanning electron microscopy.

  18. Fatigue Behavior of Steel Fiber Reinforced High-Strength Concrete under Different Stress Levels

    Science.gov (United States)

    Zhang, Chong; Gao, Danying; Gu, Zhiqiang

    2017-12-01

    The investigation was conducted to study the fatigue behavior of steel fiber reinforced high-strength concrete (SFRHSC) beams. A series of 5 SFRHSC beams was conducted flexural fatigue tests at different stress level S of 0.5, 0.55, 0.6, 0.7 and 0.8 respectively. Static test was conducted to determine the ultimate static capacity prior to fatigue tests. Fatigue modes and S-N curves were analyzed. Besides, two fatige life prediction model were analyzed and compared. It was found that stress level S significantly influenced the fatigue life of SFRHSC beams and the fatigue behavior of SFRHSC beams was mainly determined by the tensile reinforcement.

  19. Fatigue crack growth and endurance data on 9% Cr 1% Mo steels for AGR applications

    International Nuclear Information System (INIS)

    Priddle, E.K.

    1987-01-01

    Experimental investigations have been carried out on 9%Cr 1%Mo steels to examine: (1) The significance of carburisation on the fatigue endurance of plain and welded boiler tubes, and tube spacer strip; (2) the high cycle fatigue endurance of spacer strip and spacer weld metal; (3) fatigue crack growth rates in spacer strip and spacer weld metal. This report summarises the results of these investigations and where necessary compares the data to that in current data sheets. The effects of carburisation are variable depending on the structure and type of carburisation. The fatigue endurance properties of spacer strip and spacer weld metal are also similar and need not be considered separately for assessment or design purposes. Fatigue crack growth rates in spacer strip and space weld metal are similar and are influenced by both stress ratio and temperature. A design curve from a fast reactor data sheet may be used as an upper bound to these fatigue crack growth results. (author)

  20. Low cycle fatigue strength of some austenitic stainless steels at room temperature and elevated temperatures

    International Nuclear Information System (INIS)

    Type 304, 316, and 316L stainless steels were tested from room temperature to 650 0 C using two kinds of bending test specimens. Particularly, Type 304 was tested at several cyclic rates and 550 0 and 650 0 C, and the effect of cyclic rate on its fatigue strength was investigated. Test results are summarized as follows: (1) The bending fatigue strength at room temperature test shows good agreement with the axial fatigue one, (2) Manson--Coffin's fatigue equation can be applied to the results, (3) the ratio of crack initiation to failure life becomes larger at higher stress level, and (4) the relation between crack propagation life and total strain range or elastic strain range are linear in log-log scale. This relation also agrees with the equations which were derived from some crack propagation laws. It was also observed at the elevated temperature test: (1) The reduction of fatigue strength is not noticeable below 500 0 C, but it is noted at higher temperature. (2) The cycle rate does not affect on fatigue strength in faster cyclic rate than 20 cpm and below 100,000 cycles life range. (3) Type 316 stainless steel shows better fatigue property than type 304 and 316L stainless steels. 30 figures

  1. Mechanical properties of reactor pressure vessel steels studied by static and dynamic torsion tests

    International Nuclear Information System (INIS)

    Munier, A.; Maamouri, M.; Schaller, R.; Mercier, O.

    1993-01-01

    Internal friction measurements and torsional plastic deformation tests have been performed in reactor pressure vessel steels (unirradiated, irradiated and irradiated/annealed specimens). The results of these experiments have been interpreted with help of transmission electron microscopy observations (conventional and in situ). It is shown how the interactions between screw dislocations and obstacles (Peierls valleys, impurities and precipitates) could explain the low temperature hardening and the irradiation embrittlement of ferritic steels. In addition, it appears that the nondestructive internal friction technique could be used advantageously to follow the evolution of the material properties under irradiation, as for instance the irradiation embrittlement of the reactor pressure vessel steels. (orig.)

  2. Microstructure and fatigue properties of Mg-to-steel dissimilar resistance spot welds

    International Nuclear Information System (INIS)

    Liu, L.; Xiao, L.; Chen, D.L.; Feng, J.C.; Kim, S.; Zhou, Y.

    2013-01-01

    Highlights: ► Mg/steel dissimilar spot weld had the same fatigue strength as Mg/Mg similar weld. ► Crack propagation path of Mg/Mg and Mg/steel welds was the same. ► Penetration of Zn into the Mg base metal led to crack initiation of Mg/steel weld. ► HAZ weakening and stress concentration led to crack initiation of Mg/Mg weld. -- Abstract: The structural application of lightweight magnesium alloys in the automotive industry inevitably involves dissimilar welding with steels and the related durability issues. This study was aimed at evaluating the microstructural change and fatigue resistance of Mg/steel resistance spot welds, in comparison with Mg/Mg welds. The microstructure of Mg/Mg spot welds can be divided into: base metal, heat affected zone and fusion zone (nugget). However, the microstructure of Mg/steel dissimilar spot welds had three different regions along the joined interface: weld brazing, solid-state joining and soldering. The horizontal and vertical Mg hardness profiles of Mg/steel and Mg/Mg welds were similar. Both Mg/steel and Mg/Mg welds were observed to have an equivalent fatigue resistance due to similar crack propagation characteristics and failure mode. Both Mg/steel and Mg/Mg welds failed through thickness in the magnesium sheet under stress-controlled cyclic loading, but fatigue crack initiation of the two types of welds was different. The crack initiation of Mg/Mg welds was occurred due to a combined effect of stress concentration, grain growth in the heat affected zone (HAZ), and the presence of Al-rich phases at HAZ grain boundaries, while the penetration of small amounts of Zn coating into the Mg base metal stemming from the liquid metal induced embrittlement led to crack initiation in the Mg/steel welds.

  3. VVER vessel steel corrosion at interaction with molten corium in oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation)], E-mail: bechta@sbor.spb.su; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V.; Almiashev, V.I. [Institute of Silicate Chemistry, Russian Academy of Sciences (ISCh RAS), St. Petersburg (Russian Federation); Lopukh, D.B. [SPb State Electrotechnical University (SPbGETU), St. Petersburg (Russian Federation); Bottomley, D. [EUROPAISCHE KOMMISSION, Joint Research Centre Institut fuer Transurane (ITU), Karlsruhe (Germany); Fischer, M. [AREVA NP GmbH, Erlangen (Germany); Piluso, P. [CEA/DEN/DSNI, Saclay (France); Miassoedov, A.; Tromm, W. [Forschungszentrum Karlsruhe, Karlsruhe (Germany); Altstadt, E. [Forschungszentrum Rossendorf (FZR), Dresden (Germany); Fichot, F. [IRSN/DPAM/SEMCA, St. Paul lez Durance (France); Kymalainen, O. [FORTUM Nuclear Services Ltd., Espoo (Finland)

    2009-06-15

    The long-term in-vessel corium retention (IVR) in the lower head bears a risk of the vessel wall deterioration caused by steel corrosion. The ISTC METCOR Project has studied physicochemical impact of prototypic coria having different compositions in air and steam and has generated valuable experimental data on vessel steel corrosion. It is found that the corrosion rate is sensitive to corium composition, but the composition of oxidizing above-melt atmosphere (air, steam) has practically no influence on it. A model of the corrosion process that integrates the experimental data, is proposed and used for development of correlations.

  4. VVER vessel steel corrosion at interaction with molten corium in oxidizing atmosphere

    International Nuclear Information System (INIS)

    Bechta, S.V.; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A.; Gusarov, V.V.; Almiashev, V.I.; Lopukh, D.B.; Bottomley, D.; Fischer, M.; Piluso, P.; Miassoedov, A.; Tromm, W.; Altstadt, E.; Fichot, F.; Kymalainen, O.

    2009-01-01

    The long-term in-vessel corium retention (IVR) in the lower head bears a risk of the vessel wall deterioration caused by steel corrosion. The ISTC METCOR Project has studied physicochemical impact of prototypic coria having different compositions in air and steam and has generated valuable experimental data on vessel steel corrosion. It is found that the corrosion rate is sensitive to corium composition, but the composition of oxidizing above-melt atmosphere (air, steam) has practically no influence on it. A model of the corrosion process that integrates the experimental data, is proposed and used for development of correlations.

  5. Microstructural evolution of aged heat-resistant cast steel following strain controlled fatigue

    International Nuclear Information System (INIS)

    Golański, Grzegorz; Zielińska-Lipiec, Anna; Mroziński, Stanisław; Kolan, Cezary

    2015-01-01

    The paper presents the results of research on the microstructure of high-chromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel after the isothermal ageing process and fatigue process. The fatigue process was performed at room temperature and elevated temperature (600 °C), with the value of total strain amplitude ε ac amounting to 0.25% and 0.60%. Microstructural tests of GP91 cast steel were carried out by means of high-resolution transmission electron microscope. Quantitative study performed by means of TEM included the characteristics of changes in the dislocation substructure and morphology of M 23 C 6 carbides. Performed research has shown that the microstructure of the examined cast steel after ageing is characterized by partly remaining lath microstructure with numerous precipitations of the MX and M 23 C 6 type, as well as the Laves phase. It has been shown that the fatigue test at room temperature contributes to the process of dislocation strengthening of the examined cast steel. The increase of fatigue test temperature influences the degree of increase in the matrix softening. The degree of softening of the cast steel microstructure at elevated temperature depends also on the value of strain amplitude ε ac . The softening process of the examined cast steel was connected with the decrease of dislocation density and increase of subgrains

  6. Applicability of newly developed 610MPa class heavy thickness high strength steel to boiler pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Norihiko; Kaihara, Shoichiro; Ishii, Jun [Ishikawajima-Harima Heavy Industries Corp., Yokohama (Japan); Kajigaya, Ichiro [Ishikawajima-Harima Heavy Industries Corp., Tokyo (Japan); Totsuka, Takehiro; Miyazaki, Takashi [Ishikawajima-Harima Heavy Industries Corp., Aioi (Japan)

    1995-11-01

    Construction of a 350 MW Class PFBC (Pressurized Fluidized Bed Combustion) boiler plant is under planning in Japan. Design temperature and pressure of the vessel are maximum 350 C and 1.69 MPa, respectively. As the plate thickness of the vessel exceeds over 100 mm, high strength steel plate of good weldability and less susceptible to reheat cracking was required and developed. The steel was aimed to satisfy the tensile strength over 610 MPa at 350 C after postweld heat treatment (PWHT), with good notch toughness. The authors investigated the welding performances of the newly developed steel by using 150 mm-thick plate welded by pulsed-MAG and SAW methods. It was confirmed that the newly developed steel and its welds possess sufficient strength and toughness after PWHT, and applicable to the actual pressure vessel.

  7. Development of improved SGV480 steel plate for containment vessel in PWR plants

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Norioki [Advanced Nuclear Equipment Research Inst., Tokyo (Japan); Morikage, Yasushi; Okayama, Yutaka; Higashikubo, Tomohiro

    2001-01-01

    When a nuclear containment vessel made of steel plate at PWR plants in Japan is produced, SGV480 steel plate made by annealing method according to JIS G3118 is usually used in main. And, when thickness of welding portion of the vessel is larger than 38 mm, as heat treatment after welding is regulated to carry out according to the ministerial ordinance, it is difficult in actual to carry out the heat treatment of the actual welded portions. In a leading plant, approval of welding using a special method without heat treatment less than 47.25 mm of SGV480 carbon steel plate for JIS G3118 middle and ordinary pressure vessel was carried out to supply it for actual use. And, it is required for protection of welding fracture to carry out pre-heat treatment before welding. Because of increasing plate thickness requiring for lower temperature and more seismic resistance in construction condition, in order to produce a containment vessel without heat treatment after welding, more toughness is required for using material and welded portion. Therefore, a new SGV480 steel plate was developed by using TMCP method of modern steel manufacturing technology, to establish lower carbon equivalence and finer texture with upgrading of both toughness and weldability, without heat treatment after welding and pre-heat treatment before welding, at the Shin-Nippon Steel Co, Ltd. and Kawasaki Steel, Co. Ltd., respectively. (G.K.)

  8. Analyses of a steel containment vessel with an outer contact structure under severe internal overpressurization conditions

    International Nuclear Information System (INIS)

    Porter, V.L.

    1993-01-01

    Many Mark-I and Mark-II BWR plants are designed with a steel vessel as the primary containment. Typically, the steel containment vessel (SCV) is enclosed within a reinforced concrete shield building with only a small gap (50--90mm) separating the two structures. This paper describes finite element analyses performed to evaluate the effects of contact and friction between a steel containment vessel and an outer contact structure when the containment vessel is subjected to large internal pressures. These computations were motivated by a joint program on containment integrity involving the Nuclear Power Engineering Corporation (NUPEC) of Japan, the US Nuclear Regulatory Commission (NRC), and Sandia National Laboratories for testing model containments

  9. Equi-biaxial loading effect on austenitic stainless steel fatigue life

    Directory of Open Access Journals (Sweden)

    C. Gourdin

    2016-10-01

    Full Text Available Fatigue lifetime assessment is essential in the design of structures. Under-estimated predictions may result in unnecessary in service inspections. Conversely, over-estimated predictions may have serious consequences on the integrity of structures. In some nuclear power plant components, the fatigue loading may be equibiaxial because of thermal fatigue. So the potential impact of multiaxial loading on the fatigue life of components is a major concern. Meanwhile, few experimental data are available on austenitic stainless steels. It is essential to improve the fatigue assessment methodologies to take into account the potential equi-biaxial fatigue damage. Hence this requires obtaining experimental data on the considered material with a strain tensor in equibiaxial tension. Two calibration tests (with strain gauges and image correlation were used to obtain the relationship between the imposed deflection and the radial strain on the FABIME2 specimen. A numerical study has confirmed this relationship. Biaxial fatigue tests are carried out on two austenitic stainless steels for different values of the maximum deflection, and with a load ratio equal to -1. The interpretation of the experimental results requires the use of an appropriate definition of strain equivalent. In nuclear industry, two kinds of definition are used: von Mises and TRESCA strain equivalent. These results have permitted to estimate the impact of the equibiaxiality on the fatigue life of components

  10. Sequential creep-fatigue interaction in austenitic stainless steel type 316L-SPH

    International Nuclear Information System (INIS)

    Tavassoli, A.A.; Mottot, M.; Petrequin, P.

    1986-01-01

    Influence of a prior creep or fatigue exposure on subsequent fatigue or creep properties of stainless steel type 316 L SPH has been investigated. The results obtained are used to verify the validity of time and cycle fraction rule and to obtain information on the effect of very long intermittent hold times on low cycle fatigue properties, as well as on transitory loads occurring during normal service of some structural components of LMFBR reactors. Creep and fatigue tests have been carried out at 600 0 C and under conditions yielding equal or different fatigue saturation and creep stresses. Prior creep damage levels introduced range from primary to tertiary creep, whilst those of fatigue span from 20 to 70 percent of fatigue life. In both creep-fatigue and fatigue-creep sequences in the absence of a permanent prior damage (cavitation or cracking) the subsequent resistance of 316 L-SPH to fatigue or creep is unchanged, if not improved. Thin foils prepared from the specimens confirmed these observations and showed that the dislocation substructure developed during the first mode of testing is quickly replaced by that of the second mode. Grain boundary cavitation does not occur in 316 L-SPH during creep exposures to well beyond the apparent end of secondary stage and as a result prior creep exposures up to approximately 80% of rupture life do not affect fatigue properties. Conversely, significant surface cracks were found in the prior fatigue tested specimens after above about 50% life. In the presence of such cracks the subsequent creep damage was localized at the tip of the main crack and the remaining creep life was found to be usually proportional to the effective specimen cross section. Creep and fatigue sequential damage are not necessarily additive and this type of loadings are in general less severe than the repeated creep-fatigue cycling. 17 refs.

  11. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel...... the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing...... in mass production and some inherent initial problems are discussed. The treatment of a few critical welds leads to a significant increase in fatigue performance of the entire structure and the possibility for better utilization of very high-strength steel....

  12. Influence of defects on axial fatigue strength of maraging steel specimens produced by additive manufacturing

    Directory of Open Access Journals (Sweden)

    Rigon Daniele

    2018-01-01

    Full Text Available Nowadays many materials such as steels, aluminium and titanium alloys can be realised by powder bed solutions melting subsequently powder layers by means of a laser or electron beam (Laser Beam Melting – LBM and Electron Beam Melting – EBM. The microstructure realised by layer-by-layer solidification having high cooling rate cannot be considered isotropic. Therefore, the mechanical properties could be influenced by the building direction. Regarding maraging steel, the study of the influence of the building direction and the heat treatment on the static and axial fatigue strength has been investigated in a previous contribution. A large scatter of the fatigue test results was found because of the presence of detrimental surface and subsurface defects. The aim of this contribution is to present additional axial fatigue test results of maraging steel characterized by different build orientation and providing an analysis of the defects observed at the crack initiation area of the fracture surface.

  13. Hydrogen Embrittlement Mechanism in Fatigue Behaviour of Austenitic and Martensitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Brück Sven

    2018-01-01

    Full Text Available In the present study, the influence of hydrogen on the fatigue behaviour of the high strength martensitic stainless steel X3CrNiMo13-4 and the metastable austenitic stainless steels X2Crni19-11 with various nickel contents was examined in the low and high cycle fatigue regime. The focus of the investigations was the changes in the mechanisms of short crack propagation. The aim of the ongoing investigation is to determine and quantitatively describe the predominant processes of hydrogen embrittlement and their influence on the short fatigue crack morphology and crack growth rate. In addition, simulations were carried out on the short fatigue crack growth, in order to develop a detailed insight into the hydrogen embrittlement mechanisms relevant for cyclic loading conditions.

  14. Comparison of various 9-12%Cr steels under fatigue and creep-fatigue loadings at high temperature

    International Nuclear Information System (INIS)

    Fournier, B.; Dalle, F.; Sauzay, M.; Longour, J.; Salvi, M.; Caes, C.; Tournie, I.; Giroux, P.F.; Kim, S.H.

    2011-01-01

    The present article compares the cyclic behaviour of various 9-12%Cr steels, both commercial grades and optimized materials (in terms of creep strength). These materials were subjected to high temperature fatigue and creep-fatigue loadings. TEM examinations of the microstructure after cyclic loadings were also carried out. It appears that all the tempered ferritic-martensitic steels suffer from a cyclic softening effect linked to the coarsening of the sub-grains and laths and to the decrease of the dislocation density. These changes of the microstructure lead to a drastic loss in creep strength for all the materials under study. However, due to a better precipitation state, several materials optimized for their creep strength still present a good creep resistance after cyclic softening. These results are discussed and compared to the literature in terms of the physical mechanisms responsible for cyclic and creep deformation at the microstructural scale. (authors)

  15. Effect of microstructure on low cycle fatigue properties of ODS steels

    Czech Academy of Sciences Publication Activity Database

    Kuběna, Ivo; Fournier, B.; Kruml, Tomáš

    2012-01-01

    Roč. 424, 1-3 (2012), s. 101-108 ISSN 0022-3115 R&D Projects: GA ČR GA106/09/1954; GA MŠk(CZ) ED1.1.00/02.0068 Institutional research plan: CEZ:AV0Z20410507 Keywords : ODS steels * low cycle fatigue * fusion energy Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.211, year: 2012

  16. Influence of laser hardening with weld penetration onto mechanical and fatigue properties of 40H steel

    International Nuclear Information System (INIS)

    Napadlek, W.; Przetakiewicz, W.

    2003-01-01

    In the article were described investigations results of mechanical properties (hardness, R 0.2 , R m , A 5 , Z) and fatigue properties (rotary bending) of the 40H steel samples, being quenched and tempered, induction and laser hardened. In the laser hardened samples with weld penetration of top layer cracking process in fatigue strength is started mainly in weld penetration area as structural notch. (author)

  17. Surface profile evolution and fatigue crack initiation in Sanicro 25 steel at room temperature

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Petráš, Roman; Chai, G.; Škorík, Viktor

    2016-01-01

    Roč. 658, MAR (2016), s. 221-228 ISSN 0921-5093 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA MŠk(CZ) EE2.3.30.0063; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : Sanicro 25 steel * Fatigue crack initiation * Persistent slip markings * Extrusions * Intrusions Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 3.094, year: 2016

  18. A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint)

    Science.gov (United States)

    2011-03-01

    34Application of a Weakest-Link Concept to the Fatigue Limit of the Bearing Steel Sae 52100 in a Bainitic Condition," Fatigue and Fracture of...AFRL-RX-WP-TP-2011-4206 A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) S. Ekwaro-Osire and H.V. Kulkarni Texas...2011 4. TITLE AND SUBTITLE A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

  19. Optimization of fatigue damage indication in ferromagnetic low carbon steel

    Czech Academy of Sciences Publication Activity Database

    Tomáš, Ivan; Kovářík, O.; Kadlecová, Jana; Vértesy, G.

    2015-01-01

    Roč. 26, č. 9 (2015), 095603 ISSN 0957-0233 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:68378271 Keywords : fatigue * residual lifetime * magnetic non-destructive evaluation * ferromagnetic construction materials Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.492, year: 2015

  20. Analysis of bearing steel exposed to rolling contact fatigue

    DEFF Research Database (Denmark)

    Hansen, K. T.; Fæster, Søren; Natarajan, Anand

    2017-01-01

    The objective of this work is to characterize fatigue damage in roller bearings under conditions of high load and slippage. A test rig constructed for rolling contact fatigue tests of rings is described, and test results are presented for rings taken from two spherical roller bearings. The prepar...

  1. Effect of temperature on the rate of fatigue crack propagation in some steels during low cycle fatigue

    International Nuclear Information System (INIS)

    Taira, S.; Fujino, M.; Maruyama, S.

    Temperature dependence of the rate of fatigue crack propagation in steels was examined, and compared with the temperature dependence of tensile ductility. Microcracks initiate and affect the propagation behavior of the main crack at elevated temperatures. Factors found to be elucidated include initiation rate of microcracks, reduction of ductility of the material in the vicinity of the main crack tip, and relaxation of concentrated strain by multi-cracks. It was found that during a strain controlled low cycle fatigue test at 1 cpm, the rate of crack propagation is largest at the blue-brittleness temperature range (200 to 300 0 C) in a low carbon steel. On the other hand, it is largest at above 700 0 C in austenite stainless steels. The temperature dependence of the rate of fatigue crack propagation is opposite to that of tensile ductility. Microcracks formed in the vicinity of the main crack tip were calculated, by considering the strain concentration and strain cycles imposed. Then, the local fracture strain was evaluated. Good correlation was found between the rate of crack propagation and the local fracture strain. (U.S.)

  2. Effects of a laser surface processing induced heat-affected zone on the fatigue behavior of AISI 4340 steel

    International Nuclear Information System (INIS)

    McDaniels, R.L.; White, S.A.; Liaw, K.; Chen, L.; McCay, M.H.; Liaw, P.K.

    2008-01-01

    The effects of the heat-affected zone (HAZ) in AISI 4340 steel created by laser-surface alloying (LSA) on high-cycle fatigue behavior have been investigated. This research was performed by producing several lots of laser-processed AISI 4340 steel using different laser processing parameters, and then subjecting the samples to high-cycle fatigue and Knoop microindentation hardness studies. Samples of tested material from each lot were examined using scanning-electron microscopy (SEM) in order to establish the effects of laser processing on the microstructure of the fatigue-tested AISI 4340 steel. When these three techniques, microindentation hardness testing, high-cycle fatigue testing, and SEM, are combined, a mechanistic understanding of the effect of the HAZ on the fatigue behavior of this alloy might be gained. It was found that the HAZ did not appear to have an adverse effect on the high-cycle fatigue behavior of LSA-processed AISI 4340 steel

  3. Effect of Deoxidation Process on Inclusion and Fatigue Performance of Spring Steel for Automobile Suspension

    Science.gov (United States)

    Hu, Yang; Chen, Weiqing; Wan, Changjie; Wang, Fangjun; Han, Huaibin

    2018-04-01

    55SiCrA spring steel was smelted in a vacuum induction levitation furnace. The liquid steel was treated by Si deoxidation, Al modification with Ca treatment and Al modification, and the steel samples were obtained with deformable Al2O3-SiO2-CaO-MgO inclusions closely contacted with steel matrix, Al2O3-CaO-CaS-SiO2-MgO inclusions surrounded by small voids or Al2O3(> 80 pct)-SiO2-CaO-MgO inclusions surrounded by big voids, respectively. Effect of three types of inclusions on steel fatigue cracks was studied. The perpendicular and transverse fatigue cracks around the three types of inclusions leading to fracture were found to vary in behavior. Under the applied stress amplitude of 775 MPa, the fatigue lives of the three spring steels decreased from 4.0 × 107 to 3.8 × 107, and to 3.1 × 107 cycles. For the applied stress amplitude of 750 MPa, the fatigue lives of the three spring steels decreased from 5.2 × 107 to 4.1 × 107, and to 3.4 × 107 cycles. Based on the voids around inclusions, the equivalent size of initial fatigue crack has been newly defined as √ {{{area}_{inclusion} }/{(1 - {CC)}}} , where the contraction coefficient CC of inclusion was introduced. A reliable forecast model of the critical size of inclusion leading to fracture was established by the incorporation of actual width b inclusion or diameter d inclusion of internal inclusion; the model prediction was found to be in agreement with experimental results.

  4. Quantitative Acoustic Emission Fatigue Crack Characterization in Structural Steel and Weld

    Directory of Open Access Journals (Sweden)

    Adutwum Marfo

    2013-01-01

    Full Text Available The fatigue crack growth characteristics of structural steel and weld connections are analyzed using quantitative acoustic emission (AE technique. This was experimentally investigated by three-point bending testing of specimens under low cycle constant amplitude loading using the wavelet packet analysis. The crack growth sequence, that is, initiation, crack propagation, and fracture, is extracted from their corresponding frequency feature bands, respectively. The results obtained proved to be superior to qualitative AE analysis and the traditional linear elastic fracture mechanics for fatigue crack characterization in structural steel and welds.

  5. Thermoelastoviscoplastic modeling of RAFM steel JLF-1 using tensile and low cycle fatigue experiments

    Energy Technology Data Exchange (ETDEWEB)

    Msolli, S., E-mail: sabeur.msolli@univ-lorraine.fr

    2014-08-01

    In this paper, a modeling of the elastoviscoplastic behavior of a Reduced Activation Ferritic Martensitic (RAFM) steel JLF-1 is presented. The modeling of this material was based on various Low Cycle Fatigue (LCF) and tensile tests performed in air and vacuum using different imposed strain rates and temperature ranges going from ambient temperature to 873 K. The coupled viscoplastic model is coded in FORTRAN program, implemented into the finite elements code ABAQUS and used to predict the thermomechanical behavior of a fatigue specimen made of RAFM steel JLF-1. Good agreements were found between numerical results and experimental data.

  6. The effect of metastability in the process of fatigue of an austenitic stainless steel

    International Nuclear Information System (INIS)

    Pacheco, D.J.

    1977-01-01

    The influence of martensitic phase transformation on the process of pulsating tensile stress is studied in a metastable type AISI 316 stainless steel in the temperature range from 25 to -196 0 C. Annealed as well as previously deformed specimens are tested for the typical microstructural characteristics. It is concluded that the fatigue limit as well as the crack mechanisms depend upon the nature of the slip of crystalographic planes. The martensitic transformation previously induced by plastic deformation shows an undesirable fatigue character, in the annealed state and tested at 25 0 C, the type 316 steel will need a plastic deformation equal to or slightly above 9% for pulsating tension fracture [pt

  7. Fatigue-crack growth behavior of Type 347 stainless steels under simulated PWR water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seokmin; Min, Ki-Deuk; Yoon, Ji-Hyun; Kim, Min-Chul; Lee, Bong-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Fatigue crack growth rate (FCGR) curve of stainless steel exists in ASME code section XI, but it is still not considering the environmental effects. The longer time nuclear power plant is operated, the more the environmental degradation issues of materials pop up. There are some researches on fatigue crack growth rate of S304 and S316, but researches of FCGR of S347 used in Korea nuclear power plant are insufficient. In this study, the FCGR of S347 stainless steel was evaluated in the PWR high temperature water conditions. The FCGRs of S347 stainless steel under pressurized-water conditions were measured by using compact-tension (CT) specimens at different levels of dissolved oxygen (DO) and frequency. 1. FCGRs of SS347 were slower than that in ASME XI and environmental effect did not occur when frequency was higher than 1Hz. 2. Fatigue crack growth is accelerated by corrosion fatigue and it is more severe when frequency is slower than 0.1Hz. 3. Increase of crack tip opening time increased corrosion fatigue and it deteriorated environmental fatigue properties.

  8. On the adsorption-induced fatigue of structural steels in the presence of alcohols

    International Nuclear Information System (INIS)

    Loboiko, V.I.; Karpenko, G.V.; Vasilenko, I.I.

    1976-01-01

    The purpose of the work was to study he effect of anhydrous alcohols on the cyclic fatigue of steels in the absence of contact of the alcohol with atmospheric moisture during the testing process. A vacuum was created in the operating space and then the vacuum annealing was carried out in a bath with the sample and through metal vacuum connection the bath was filled with anhydrous alcohol. Studies were made on several construction steels (20Kh, 40Kh, 50Kh, and ShKh15); steels 40Kh, 50Kh, and ShKh15 were quenched from 840-860 0 C in oil and then tempered at 200 0 C (2 h), steel 20Kh was studied in the as-received state. It was shown that with increase in the carbon content of steel with a martensite structure, the decrease in strength in the presence of anhydrous alcohol was greater than in dry air. Experiments showed that anhydrous alcohol causes an adsorption decrease in the strength both of samples with preliminarily formed cracks and V-shaped stress concentrators and of smooth samples. The greatest adsorption effect of alcohols in our case, as in static fatigue, was observed in samples with cracks. A dependence was shown between the length of the carbon chain and the fatigue limit. This dependence indicates the monotone nature of the decrease in the fatigue limit with transfer from methyl to butyl and then to octyl alcohol

  9. Influence of surface defects on the fatigue crack initiation in pearlitic steel

    Directory of Open Access Journals (Sweden)

    Toribio Jesús

    2014-06-01

    Full Text Available Tensile fatigue tests were performed under load control, with constant stress range Δσ on pearlitic steel wires, from the hot rolled bar to the commercial prestressing steel wire (which has undergone seven cold drawing steps. Results show that fatigue cracks in pearlitic steels initiate at the wire surface starting from small defects, whose size decreases with the drawing process. Fatigue cracks created from defects (initiation phase exhibit a fractographic appearance consisting of ductile microtearing events which can be classified as tearing topography surface or TTS, and exhibit a remarkably lower spacing in the prestressing steel wire than in the hot rolled bar. In addition, some S-N tests were performed in both material forms under a stress range of about half the yield strength. In these tests, the main part of the fatigue life corresponds to the propagation stage in the hot rolled bar whereas such a main part of the life is associated with the initiation stage in the case of the prestressing steel wire.

  10. Hydrogen induced plastic damage in pressure vessel steel of 2.25Cr-1Mo

    International Nuclear Information System (INIS)

    Han, G.W.; Song, Y.J.

    1995-01-01

    2.25Cr-1Mo steel is generally employed as a hydrogenation reaction vessel material used at elevated temperature and in a hydrogen containing environment. During service of the reaction vessel, a large number of hydrogen atoms would enter its wall. When the reaction vessel is shutdown and the temperature reduces to about ambient temperature, the hydrogen atoms remaining in the wall would induce plastic damage in the steel. The mechanism of hydrogen induced plastic damage is different for various materials with different microstructures. Investigations have demonstrated that the hydrogen induced plastic damage in carbide annealed carbon steels is caused by hydrogen accelerating the initiating and growing of microvoids from the carbide particles. However, SEM examination on the fracture surface of hydrogen charged tensile specimen of 2.25Cr-1Mo steel show that a large number of fisheyes appear on the fracture surface. This indicates that hydrogen induced plastic damage in 2.25Cr-1Mo steel is related to the occurrence of fisheye cracks during plastic deformation. By means of micro-fracture mechanics to analyze fisheye crack occurrence from the first generation microvoid, the mechanism of hydrogen induced plastic damage in the pressure vessel steel is investigated

  11. Effects of irradiation on low cycle fatigue properties for reduced activation ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Kim, S.W.; Tanigawa, H.; Hirose, T.; Kohyama, A.

    2007-01-01

    Full text of publication follows: In materials life decision for a commercial blanket, thermal fatigue property of materials is a particularly important. The loading of structural materials in fusion reactor is, besides the plasma surface interactions, a combined effect of high heat fluxes and neutron irradiation. Depending on the pulse lengths, the operating conditions, and the thermal conductivity, these oscillating temperature gradients will cause elastic and elastic-plastic cyclic deformation giving rise to (creep-) fatigue in structural first wall and blanket components. Especially, investigation of the fatigue property in Reduced Activation Ferritic/Martensitic (RAF/M) steel and establishment of the evaluation technology are demanded in particular immediately for design/manufacturing of ITER-TBM. And also, fatigue testing after irradiation will be carried out in hot cells with remote control system. Considering limited ability of specimen manipulation in the cells, the specimen and the test method need to be simple for operation. The existing data bases of RAF/M steel provide baseline data set including post-irradiation fatigue data. However, to perform the accurate fatigue lifetime assessment for ITER-TBM and beyond utilizing the existing data base, the mechanical understanding of fatigue fracture is mandatory. It has been previously reported by co-authors that dislocation cell structure was developed on low cycle fatigued RAF/M steel, and led the fatigue crack to develop along prior austenitic grain boundary. In this work, the effects of nuclear irradiation on low cycle fatigue properties for RAF/M steels and its fracture mechanisms were examined based on the flow stress analysis and detailed microstructure analysis. Fracture surfaces and crack initiation site were investigated by scanning electron microscope (SEM). Transmission electron microscopy (TEM) was also applied to clarify the microstructural features of fatigue behavior. It is also important to

  12. Behaviour under fatigue of AISI 304-L stainless steel welded joints

    International Nuclear Information System (INIS)

    Scal, M.W.; Joia, C.J.B.M.; Sousa e Silva, A.S. de

    1979-01-01

    The fatigue behaviour at room temperature of AISI-304-L stainless steel welded joints obtained by two distinct welding methods was studied. The results obtained were compared to those characteristic of the base metal. The welded joint fatigue samples were rectified in order to eliminate the effect of the welded seam geometry. It was concluded that the mechanisms of fatigue crack start in this case is commanded by the austenitic matrix, there being no influence of the delta ferrite rate and distribution present at the melted zone. (Author) [pt

  13. Fatigue damage evaluation of austenitic stainless steel using nonlinear ultrasonic waves in low cycle regime

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianfeng; Xuan, Fu-Zhen, E-mail: fzxuan@ecust.edu.cn [MOE Key Laboratory of Pressurized System and Safety, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2014-05-28

    The interrupted low cycle fatigue test of austenitic stainless steel was conducted and the dislocation structure and fatigue damage was evaluated subsequently by using both transmission electron microscope and nonlinear ultrasonic wave techniques. A “mountain shape” correlation between the nonlinear acoustic parameter and the fatigue life fraction was achieved. This was ascribed to the generation and evolution of planar dislocation structure and nonplanar dislocation structure such as veins, walls, and cells. The “mountain shape” correlation was interpreted successfully by the combined contribution of dislocation monopole and dipole with an internal-stress dependent term of acoustic nonlinearity.

  14. Small fatigue crack propagation in Y2O3 strengthened steels

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Kuběna, Ivo; Ševčík, Martin; Šmíd, Miroslav; Kruml, Tomáš; Náhlík, Luboš

    2014-01-01

    Roč. 452, 1-3 (2014), s. 370-377 ISSN 0022-3115 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA MŠk(CZ) ED1.1.00/02.0068; GA ČR(CZ) GP13-28685P Institutional support: RVO:68081723 Keywords : oxide dispersion strengthened steel * small fatigue crack * J-integral * fatigue life prediction Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.865, year: 2014

  15. A study on the fatigue strength characteristics of ship structural steel with gusset welds

    Directory of Open Access Journals (Sweden)

    Sung-Jo Park

    2012-06-01

    Full Text Available This study aims to assess fatigue property by the static overload and average load in the fillet welded joints which is on the ship structural steel having gusset welds. To this end, a small specimen was made, to which the same welding condition for the actual ship structure was applied, to perform fatigue tests. In this study, a method to simply assess changes in welding residual stress according to different static overload was suggested. By measuring actual strain at the weld toe, the weld stress concentration factor and property which is determined by recrystallization in the process of welding were estimated to investigate the relation between overload and fatigue strength.

  16. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. To measure the local deformations on the strands, a novel method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires...... along the length of the monostrand. Information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of a monostrand undergoing flexural deformations is provided. From the series of dynamic fatigue tests, a fretting fatigue spectrum is derived...

  17. Fatigue life prediction for a cold worked T316 stainless steel

    International Nuclear Information System (INIS)

    Manjoine, M.J.

    1983-01-01

    Permanent damage curves of initiation-life and propagation-life which predict the fatigue life of specimens of a cold-worked type 316 stainless steel under complex strain-range histories were generated by a limited test program. Analysis of the test data showed that fatigue damage is not linear throughout life and that propagation life is longer than initiation-life at high strain ranges but is shorter at low strain ranges. If permanent damage has been initiated by prior history and/or fabrication, propagation to a given life can occur at a lower strain range than that estimated from the fatigue curves for constant CSR. (author) [pt

  18. AFM study of surface relief evolution in 316L steel fatigued at low and high temperatures

    Czech Academy of Sciences Publication Activity Database

    Man, Jiří; Valtr, B.; Weidner, A.; Petrenec, Martin; Obrtlík, Karel; Polák, Jaroslav

    2010-01-01

    Roč. 2, č. 1 (2010), s. 1625-1633 E-ISSN 1877-7058. [Fatigue 2010. Praha, 06.06.2010-11.06.2010] R&D Projects: GA ČR GAP108/10/2371; GA AV ČR 1QS200410502; GA ČR GA106/06/1096 Institutional research plan: CEZ:AV0Z20410507 Keywords : Fatigue crack initiation * 316L steel * Persistent slip band (PSB) * Extrusion * Intrusion * Atomic force microscopy (AFM) Subject RIV: JL - Materials Fatigue, Friction Mechanics

  19. Effects of irradiation on low cycle fatigue properties for reduced activation ferritic/martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.W. [Kyoto Univ., Graduate School of Energy Science (Japan); Tanigawa, H. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Kohyama, A. [Kyoto Univ., lnstitute of Advanced Energy (Japan)

    2007-07-01

    Full text of publication follows: In materials life decision for a commercial blanket, thermal fatigue property of materials is a particularly important. The loading of structural materials in fusion reactor is, besides the plasma surface interactions, a combined effect of high heat fluxes and neutron irradiation. Depending on the pulse lengths, the operating conditions, and the thermal conductivity, these oscillating temperature gradients will cause elastic and elastic-plastic cyclic deformation giving rise to (creep-) fatigue in structural first wall and blanket components. Especially, investigation of the fatigue property in Reduced Activation Ferritic/Martensitic (RAF/M) steel and establishment of the evaluation technology are demanded in particular immediately for design/manufacturing of ITER-TBM. And also, fatigue testing after irradiation will be carried out in hot cells with remote control system. Considering limited ability of specimen manipulation in the cells, the specimen and the test method need to be simple for operation. The existing data bases of RAF/M steel provide baseline data set including post-irradiation fatigue data. However, to perform the accurate fatigue lifetime assessment for ITER-TBM and beyond utilizing the existing data base, the mechanical understanding of fatigue fracture is mandatory. It has been previously reported by co-authors that dislocation cell structure was developed on low cycle fatigued RAF/M steel, and led the fatigue crack to develop along prior austenitic grain boundary. In this work, the effects of nuclear irradiation on low cycle fatigue properties for RAF/M steels and its fracture mechanisms were examined based on the flow stress analysis and detailed microstructure analysis. Fracture surfaces and crack initiation site were investigated by scanning electron microscope (SEM). Transmission electron microscopy (TEM) was also applied to clarify the microstructural features of fatigue behavior. It is also important to

  20. Fatigue Crack Behavior of Stainless Steel 304 by the Addition of Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Rizwanulhaque Syed

    2014-01-01

    Full Text Available Fatigue is the main source of almost half of whole mechanical failures. This research investigated the effect on cyclic fatigue behavior of stainless steel 304 (SS304 when including carbon nanotubes (CNTs at the crack tip. The cyclic fatigue tests were conducted on compact tension (CT specimens to establish the relationship between crack growth and the number of cycles (a-N. It is found that the incorporation of a small amount of CNTs increased the fatigue life of the SS304/metal. Micrographs showed that the enhancement in fatigue life is caused by CNTs dense arrangement around the crack tip, entangled with each other, and finer grain size. Smooth bonding at the interface of the CNTs and SS304 grains is also observed.

  1. Low cycle fatigue behavior of Sanicro25 steel at room and at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Polák, Jaroslav, E-mail: polak@ipm.cz [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); CEITEC, Institute of Physics of Materials Academy of Sciences of the Czech Republic, Žižkova 22, Brno (Czech Republic); Petráš, Roman; Heczko, Milan; Kuběna, Ivo [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Kruml, Tomáš [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); CEITEC, Institute of Physics of Materials Academy of Sciences of the Czech Republic, Žižkova 22, Brno (Czech Republic); Chai, Guocai [Sandvik Materials Technology, SE-811 81 Sandviken (Sweden); Linköping University, Engineering Materials, SE-581 83 Linköping (Sweden)

    2014-10-06

    Austenitic heat resistant Sanicro 25 steel developed for high temperature applications in power generation industry has been subjected to strain controlled low cycle fatigue tests at ambient and at elevated temperature in a wide interval of strain amplitudes. Fatigue hardening/softening curves, cyclic stress–strain curves and fatigue life curves were evaluated at room temperature and at 700 °C. The internal dislocation structures of the material at room and at elevated temperature were studied using transmission electron microscopy. High resolution surface observations and FIB cuts revealed early damage at room temperature in the form of persistent slip bands and at elevated temperature as oxidized grain boundary cracks. Dislocation arrangement study and surface observations were used to identify the cyclic slip localization and to discuss the fatigue softening/hardening behavior and the temperature dependence of the fatigue life.

  2. Short fatigue cracks nucleation and growth in lean duplex stainless steel LDX 2101

    Energy Technology Data Exchange (ETDEWEB)

    Strubbia, R., E-mail: strubbia@ifir-conicet.gov.ar [Instituto de Física Rosario – CONICET, Universidad Nacional de Rosario (Argentina); Hereñú, S.; Alvarez-Armas, I. [Instituto de Física Rosario – CONICET, Universidad Nacional de Rosario (Argentina); Krupp, U. [Faculty of Engineering and Computer Science, University of Applied Sciences Osnabrück (Germany)

    2014-10-06

    This work is focused on the fatigue damage of lean duplex stainless steels (LDSSs) LDX 2101. Special interest is placed on analyzing short fatigue crack behavior. In this sense, short crack initiation and growth during low cycle fatigue (LCF) and short crack nucleation during high cycle fatigue (HCF) of this LDSS have been studied. The active slip systems and their associated Schmid factors (SF) are determined using electron backscattered diffraction (EBSD). Additionally, the dislocation structure developed during cycling is observed by transmission electron microscopy (TEM). Regardless of the fatigue regime, LCF and HCF, short cracks nucleate along intrusion/extrusions in ferritic grains. Moreover, during the LCF phase boundaries decelerate short crack propagation. These results are rationalized by the hardness of the constitutive phases and the dependence of screw dislocation mobility in the ferrite phase on strain rate and stress amplitude.

  3. Statistical analysis of fatigue strain-life data for carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Keisler, J.; Chopra, O.K.

    1995-03-01

    The existing fatigue strain vs life (S-N) data, foreign and domestic, for carbon and low-alloy steels used in the construction of nuclear power plant components have been compiled and categorized according to material, loading, and environmental conditions. A statistical model has been developed for estimating the effects of the various test conditions on fatigue life. The results of a rigorous statistical analysis have been used to estimate the probability of initiating a fatigue crack. Data in the literature were reviewed to evaluate the effects of size, geometry, and surface finish of a component on its fatigue life. The fatigue S-N curves for components have been determined by applying design margins for size, geometry, and surface finish to crack initiation curves estimated from the model

  4. Effect of Various Heat Treatment Processes on Fatigue Behavior of Tool Steel for Cold Forging Die

    Science.gov (United States)

    Jin, S. U.; Kim, S. S.; Lee, Y. S.; Kwon, Y. N.; Lee, J. H.

    Effects of various heat treatment processes, including "Q/T (quenching and tempering)", "Q/CT/T (Quenching, cryogenic treatment and tempering)", "Q/T (quenching and tempering) + Ti-nitriding" and "Q/CT/T (Cryogenic treatment and tempering) + Ti-nitriding", on S-N fatigue behavior of AISI D2 tool steel were investigated. The optical micrographs and Vicker's hardness values at near surface and core area were examined for each specimen. Uniaxial fatigue tests were performed by using an electro-magnetic resonance fatigue testing machine at a frequency of 80 Hz and an R ratio of -1. The overall resistance to fatigue tends to decrease significantly with Ti-nitriding treatment compared to those for the general Q/T and Q/CT/T specimens. The reduced resistance to fatigue with Ti-nitriding is discussed based on the microstructural and fractographic analyses.

  5. Radiation effects on low cycle fatigue properties of reduced activation ferritic/martensitic steels

    International Nuclear Information System (INIS)

    Hirose, T.; Tanigawa, H.; Ando, M.; Kohyama, A.; Katoh, Y.; Narui, M.

    2002-01-01

    The reduced activation ferritic/martensitic steel, RAFs F82H IEA heat has been fatigue-tested at ambient temperature under diametral strain controlled conditions. In order to evaluate the effects of radiation damage and transmutation damage on fatigue characteristics, post-neutron irradiation and post-helium ion implantation fatigue tests were carried out. Fracture surfaces and fatigue crack initiation on the specimen surface were observed by SEM. Low-temperature irradiation caused an increase in stress amplitude and a reduction in fatigue lifetime corresponding to radiation hardening and loss of ductility. Neutron irradiated samples showed brittle fracture surface, and it was significant for large strain tests. On the other hand, helium implantation caused delay of cyclic softening. However, brittle crack initiation and propagation did not depend on the helium concentration profiles

  6. Study on creep-fatigue life of irradiated austenitic stainless steel

    International Nuclear Information System (INIS)

    Ioka, Ikuo; Miwa, Yukio; Tsuji, Hirokazu; Yonekawa, Minoru; Takada, Fumiki; Hoshiya, Taiji

    2001-01-01

    The low cycle creep-fatigue test with tensile strain hold of the austenitic stainless steel irradiated to 2 dpa was carried out at 823K in vacuum. The applicability of creep-fatigue life prediction methods to the irradiated specimen was examined. The fatigue life on the irradiated specimen without tensile strain hold time was reduced by a factor of 2-5 in comparison with the unirradiated specimen. The decline in fatigue life of the irradiated specimen with tensile strain hold was almost equal to that of the unirradiated specimen. The creep damage of both unirradiated and irradiated specimens was underestimated by the time fraction rule or the ductility exhaustion rule. The creep damage calculated by the time fraction rule or the ductility exhaustion rule increased by the irradiation. The predictions derived from the linear damage rule are unsafe as compared with the experimental fatigue lives. (author)

  7. Fatigue crack growth rate studies on pipes and pipe welds made of austenitic stainless steel and carbon steel

    International Nuclear Information System (INIS)

    Arora, Punit; Singh, P.K.; Bhasin, Vivek; Vaze, K.K.; Pukazhendhi, D.M.; Gandhi, P.; Raghava, G.

    2011-01-01

    The objective of the present study is to understand the fatigue crack growth behavior in austenitic stainless steel and carbon steel pipes and pipe welds by carrying out analysis/predictions and experiments. The Paris law has been used for the prediction of fatigue crack growth life. To carry out the analysis, Paris constants have been determined for pipe (base) and pipe weld materials by using Compact Tension (CT)/Three Point Bend (TPB) specimens machined from the actual pipe/pipe weld. Analyses have been carried out to predict the fatigue crack growth life of pipes/pipe welds having part through cracks on the outer surface. In the analyses, Stress Intensity Factors (K) have been evaluated through two different schemes. The first scheme considers the 'K' evaluations at two points of the crack front i.e. maximum crack depth and crack tip at the outer surface. The second scheme accounts for the area averaged root mean square stress intensity factor (K RMS ) at deepest and surface points. In order to validate the analytical procedure/results, experiments have been carried out on full scale pipe and pipe welds with part through circumferential crack. Fatigue crack growth life evaluated using both schemes have been compared with experimental results. Use of stress intensity factor (K RMS ) evaluated using second scheme gives better fatigue crack growth life prediction compared to that of first scheme. (author)

  8. Dependence of Microelastic-plastic Nonlinearity of Martensitic Stainless Steel on Fatigue Damage Accumulation

    Science.gov (United States)

    Cantrell, John H.

    2006-01-01

    Self-organized substructural arrangements of dislocations formed in wavy slip metals during cyclic stress-induced fatigue produce substantial changes in the material microelastic-plastic nonlinearity, a quantitative measure of which is the nonlinearity parameter Beta extracted from acoustic harmonic generation measurements. The contributions to Beta from the substructural evolution of dislocations and crack growth for fatigued martensitic 410Cb stainless steel are calculated from the Cantrell model as a function of percent full fatigue life to fracture. A wave interaction factor f(sub WI) is introduced into the model to account experimentally for the relative volume of material fatigue damage included in the volume of material swept out by an interrogating acoustic wave. For cyclic stress-controlled loading at 551 MPa and f(sub WI) = 0.013 the model predicts a monotonic increase in Beta from dislocation substructures of almost 100 percent from the virgin state to roughly 95 percent full life. Negligible contributions from cracks are predicted in this range of fatigue life. However, over the last five percent of fatigue life the model predicts a rapid monotonic increase of Beta by several thousand percent that is dominated by crack growth. The theoretical predictions are in good agreement with experimental measurements of 410Cb stainless steel samples fatigued in uniaxial, stress-controlled cyclic loading at 551 MPa from zero to full tensile load with a measured f(sub WI) of 0.013.

  9. Effect of tungsten and tantalum on the low cycle fatigue behavior of reduced activation ferritic/martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Shankar, Vani, E-mail: vani@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mariappan, K.; Nagesha, A.; Prasad Reddy, G.V.; Sandhya, R.; Mathew, M.D.; Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Effect of tungsten and tantalum on low cycle fatigue behavior of RAFM steels. Black-Right-Pointing-Pointer Both alloying elements W and Ta improved fatigue life. Black-Right-Pointing-Pointer Increase in Ta content improved fatigue life more than W. Black-Right-Pointing-Pointer Optimization of W content at 1.4 wt.%. Black-Right-Pointing-Pointer Softening behavior closely related to W and Ta content. - Abstract: Reduced activation ferritic/martensitic (RAFM) steels are candidate materials for the test blanket modules of International Thermonuclear Experimental Reactor (ITER). Several degradation mechanisms such as thermal fatigue, low cycle fatigue, creep fatigue interaction, creep, irradiation hardening, swelling and phase instability associated irradiation embrittlement must be understood in order to estimate the component lifetime and issues concerning the structural integrity of components. The current work focuses on the effect of tungsten and tantalum on the low cycle fatigue (LCF) behavior of RAFM steels. Both alloying elements tungsten and tantalum improved the fatigue life. Influence of Ta on increasing fatigue life was an order of magnitude higher than the influence of W on improving the fatigue life. Based on the present study, the W content was optimized at 1.4 wt.%. Softening behavior of RAFM steels showed a strong dependence on W and Ta content in RAFM steels.

  10. Product consistency testing of three reference glasses in stainless steel and perfluoroalkoxy resin vessels

    International Nuclear Information System (INIS)

    Olson, K.M.; Smith, G.L.; Marschman, S.C.

    1995-03-01

    Because of their chemical durability, silicate glasses have been proposed and researched since the mid-1950s as a medium for incorporating high-level radioactive waste (HLW) generated from processing of nuclear materials. A number of different waste forms were evaluated and ranked in the early 1980s; durability (leach resistance) was the highest weighted factor. Borosilicate glass was rated the best waste form available for incorporation of HLW. Four different types of vessels and three different glasses were used to study the possible effect of vessel composition on durability test results from the Production Consistency Test (PCT). The vessels were 45-m 304 stainless steel vessels, 150-m 304 L stainless steel vessels, and 60-m perfluoroalkoxy (PFA) fluoropolymer resin vessels. The three glasses were the Environmental Assessment glass manufactured by Corning Incorporated and supplied by Westinghouse Savannah River company, and West Valley Nuclear Services reference glasses 5 and 6, manufactured and supplied by Catholic University of America. Within experimental error, no differences were found in durability test results using the 3 different glasses in the 304L stainless steel or PFA fluoropolymer resin vessels over the seven-day test period

  11. Radiation embrittlement of WWER-1000 reactor vessel steels

    International Nuclear Information System (INIS)

    Nikolaeva, A.V.; Nikolaev, Yu.A.; Kevorkyan, Yu.R.

    2001-01-01

    Results obtained on the blank samples of materials of the WWER-1000 vessels irradiated by low density neutron flux are discussed. Chemical composition of the materials is characterized by the low content of the impurities (copper and phosphorus) and high content of nickel. Dependence of the radiation embrittlement of the WWER-1000 vessel materials on metallurgic variables and damage dose is treated. The research showed that nickel largely enhanced the radiation embrittlement. New dependences for determination of the radiation embrittlement real rate of the WWER-1000 vessel materials and its conservative estimation were developed [ru

  12. Corrosion fatigue crack growth in clad low-alloy steels: Part 1, medium-sulfur forging steel

    International Nuclear Information System (INIS)

    James, L.A.; Poskie, T.J.; Auten, T.A.; Cullen, W.H.

    1996-01-01

    Corrosion fatigue crack propagation tests were conducted on a medium- sulfur ASTM A508-2 forging steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 30.3--38.3 mm, and depths of 13.1--16.8 mm. The experiments were conducted in a quasi-stagnant low-oxygen (O 2 < 10 ppb) aqueous environment at 243 degrees C, under loading conditions (ΔK, R, and cyclic frequency) conductive to environmentally-assisted cracking (EAC) in higher-sulfur steels under quasi-stagnant conditions. Earlier experiments on unclad compact tension specimens of this heat of steel did not exhibit EAC, and the present experiments on semi-elliptical surface cracks penetrating cladding also did not exhibit EAC

  13. Joining dissimilar stainless steels for pressure vessel components

    International Nuclear Information System (INIS)

    Zheng Sun; Huai-Yue Han

    1994-01-01

    A series of studies was carried out to examine the weldability and properties of dissimilar steel joints between martensitic and austenitic stainless steels - F6NM (OCrl3Ni4Mo) and AISI 347, respectively. The weldability tests included weld thermal simulation of the martensitic steel for investigating the influence of weld thermal cycles and post-weld heat treatment (PWHT) on the mechanical properties of the heat-affected zone (HAZ); implant testing for examining the tendency for cold cracking of martensitic steel; rigid restraint testing for determining hot crack susceptibility of the multi-pass dissimilar steel joints. The joints were subjected to various mechanical tests including a tensile test, bending test and impact test at various temperatures, as well as slow strain-rate test for examining the stress corrosion cracking tendency in the simulated environment of a primary circuit of a PWR. Based on the weldability tests, a welding procedure - tungsten inert gas (TIG) welding for root passes with HNiCrMo-2B wire followed by manual metal arc (MMA) welding using coated electrode ENiCrFe-3B - was developed and a PWHT at 600 deg C/2h was recommended. Furthermore, the welding of tube/tube joints between these dissimilar steels is described. (21 refs., 11 figs., 14 tabs.)

  14. Study of radiation damage of steels for light water pressure vessels at UJV

    International Nuclear Information System (INIS)

    Vacek, N.; Stoces, B.

    1980-01-01

    Preoperational determination of radiation resistance of pressure vessel steels is performed at accelerated neutron exposure in a test or materials research reactor. The results obtained at accelerated and operating exposure are not fully identical and surveillance bodies are therefore used manufactured from the pressure vessel material. Currently, the following steels are used for the manufacture of light water reactor pressure vessels: Mn-Mo-Ni (ASTM-A533-B, ASTM-A508), Cr-Mo-V (15Kh2M1FA). At UJV Rez, for irradiation Chanca-M probes imported from France are used featuring electric temperature control. Almost identical radiation embrittlement was measured for all three steels after irradiation with a neutron fluence of 3x10 23 n.m -2 at a temperature of 290 degC. (H.S.)

  15. R and D Developments. Research Programs on Irradiation Embrittlement of Reactor Vessel Steels

    International Nuclear Information System (INIS)

    Gomez Briceno, D.; Lapena, J.; Serrano, M.; Perosanz, F.

    2000-01-01

    Irradiation embrittlement of pressure vessel steels is a degradation mechanism time dependent that can lead to operational restrictions with adverse effects in the efficiency and life of a plant. For the last year, several research programs have been devoted to study thye evaluation of neutronic radiation effect on mechanical properties of pressure vessel steels. However, at the present, there is a growing interest on the development of new methodologies to optimize the surveillance program information, and the understanding of the irradiation damage mechanism. This paper give an overview of international research programs, and on the R+D activities carried out by the Structural Materials Project on irradiation embrittlement on pressure vessel steels. (Author)

  16. Fatigue crack growth retardation in spot heated mild steel sheet

    Indian Academy of Sciences (India)

    Unknown

    Department of Metallurgical Engineering, *Department of Applied Mechanics and Hydraulics, ... growth retardation increases with increasing level of overload as well as with ..... Suresh S 1996 Fatigue of materials (Cambridge: Cambridge.

  17. Oxidation effect on steel corrosion and thermal loads during corium melt in-vessel retention

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A.; Almjashev, V.I. [Alexandrov Scientific-Research Technology Institute (NITI), Sosnovy Bor (Russian Federation); Bechta, S.V. [KTH, Stockholm (Sweden); Gusarov, V.V. [SPb State Technology University (SPbGTU), St. Petersburg (Russian Federation); Barrachin, M. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), St Paul lez Durance (France); Bottomley, P.D., E-mail: paul.bottomley@ec.europa.eu [EC-Joint Research Centre, Institute for Transuranium Elements (ITU), Karlsruhe (Germany); Fischer, M. [AREVA GmbH, Erlangen (Germany); Piluso, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Cadarache, St Paul lez Durance (France)

    2014-10-15

    Highlights: • The METCOR facility simulates vessel steel corrosion in contact with corium. • Steel corrosion rates in UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} coria accelerate above 1050 K. • However corrosion rates can also be limited by melt O{sub 2} supply. • The impact of this on in-vessel retention (IVR) strategy is discussed. - Abstract: During a severe accident with core meltdown, the in-vessel molten core retention is challenged by the vessel steel ablation due to thermal and physicochemical interaction of melt with steel. In accidents with oxidizing atmosphere above the melt surface, a low melting point UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} corium pool can form. In this case ablation of the RPV steel interacting with the molten corium is a corrosion process. Experiments carried out within the International Scientific and Technology Center's (ISTC) METCOR Project have shown that the corrosion rate can vary and depends on both surface temperature of the RPV steel and oxygen potential of the melt. If the oxygen potential is low, the corrosion rate is controlled by the solid phase diffusion of Fe ions in the corrosion layer. At high oxygen potential and steel surface layer temperature of 1050 °C and higher, the corrosion rate intensifies because of corrosion layer liquefaction and liquid phase diffusion of Fe ions. The paper analyzes conditions under which corrosion intensification occurs and can impact on in-vessel melt retention (IVR)

  18. Heissdampfreaktor (HDR) steel-containment-vessel and floodwater-storage-tank structural-dynamics tests

    International Nuclear Information System (INIS)

    Arendts, J.G.

    1982-01-01

    Inertance (vibration) testing of two significant vessels at the Heissdampfreaktor (HDR) facility, located near Kahl, West Germany, was recently completed. Transfer functions were obtained for determination of the modal properties (frequencies, mode shapes and damping) of the vessels using two different test methods for comparative purposes. One of the vessels tested was the steel containment vessel (SCV). The SCV is approximately 180 feet high and 65 feet in diameter with a 1.2-inch wall thickness. The other vessel, called the floodwater storage tank (FWST), is a vertically standing vessel approximately 40 feet high and 10 feet in diameter with a 1/2-inch wall thickness. The FWST support skirt is square (in plan views) with its corners intersecting the ellipsoidal bottom head near the knuckle region

  19. Effect of Tantalum content on the low cycle fatigue properties of CLAM steel at 823 K

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Xiangwei [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China); Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Zhao, Yanyun; Wang, Kun [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

    2017-01-15

    Highlights: • The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. • The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles. • The grain size and M{sub 23}C{sub 6} were closely associated with the Ta content. • The crack distribution was quite sensitive to the Ta content. - Abstract: The effect of tantalum (Ta) content on the low cycle fatigue (LCF) properties of CLAM steel at 823 K was investigated in this paper. Low cycle fatigue tests were carried out on four ingots of CLAM steel with Ta contents of 0.027 wt%, 0.078 wt%, 0.15 wt% and 0.18 wt%, respectively. The results showed that the fatigue life and softening behavior of CLAM steel were influenced by Ta content. The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles.

  20. Study on high-cycle fatigue behavior of candidate stainless steels for SCWR

    International Nuclear Information System (INIS)

    Xiong Ru; Zhao Yuxiang; Zhang Qiang; Wang Hao; Tang Rui; Qiao Yingjie

    2013-01-01

    The fatigue experiments of commerce stainless steels including 347, 316Ti and 310 were conducted under bending and rotating loadings. The environments were at room temperature (RT) as well as at 550℃ in air. The fracture morphology was observed by SEM, and the S-N curves were processed according to the experimental data. The results indicate the fatigue limited stresses for the 3 stainless steels were in the order of 347 < 316Ti < 310, which consistent with the order of their tensile strength. Elevated temperature would accelerate the oxidation and therefore the fatigue life would decrease, among them 347 was more sensitive to temperature with the maximum decreasing tendency. All the 3 stainless steels have good resistance to high cycle fatigue when comparing their experimental data with the calculated value from the empirical formula. The fracture morphology presents areas of crack initiation, crack growth and fracture, the width of fatigue ripples is about 1 μm, the fracture area has much dimples, and 347 presents much cavities of different sizes in dimples. (authors)

  1. Effect of stress relief parameters on the mechanical properties of pressure vessel steels and weldments

    International Nuclear Information System (INIS)

    Canonico, D.A.; Stelzman, W.J.

    1976-01-01

    Post weld heat treatments of thick-section A533B steel for nuclear pressure vessels are discussed with reference to the ASME code. The discussion is in the form of a lecture and summarized by noting that the ASME code, in particular Section III, Division 1, imposes a post weld heat treatment requirement on pressure vessels fabricated from low alloy high strength steels. The Code permits a holding temperature range, the high side of which could result in poorer toughness properties. Long times in excess of 100 hours and/or high temperatures, 649 0 C can result in an increase in the NDT and a decrease in the upper shelf energy

  2. Applicability of JIS SPV 50 steel to primary containment vessels of nuclear power stations

    International Nuclear Information System (INIS)

    Iida, K.; Ishikawa, K.; Satoh, M.; Soya, I.

    1980-01-01

    The fracture toughness of JIS SPV 50 steel and its weldment has been examined in order to verify the applicability of these materials to primary containment vessels of nuclear power stations. Test results were evaluated using elastic plastic fracture mechanics through the COD and the J integral concepts for non ductile fracture initiation characteristics. Linear fracture mechanics was employed for propagation arrest characteristics. Results showed that the materials tested here have a sufficient fracture toughness to prevent nonductile fracture and that this steel is a suitable material for use in construction of primary containment vessels of nuclear power stations. (author)

  3. A study on fatigue crack growth in dual phase martensitic steel in air

    Indian Academy of Sciences (India)

    Dual phase (DP) steel was intercritically annealed at different temperatures from fully martensitic state to achieve martensite plus ferrite, microstructures with martensite contents in the range of 32 to 76%. Fatigue crack growth (FCG) and fracture toughness tests were carried out as per ASTM standards E 647 and E 399, ...

  4. Cyclic plastic response and fatigue life of duplex and superduplex stainless steel

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav

    43 2005, č. 4 (2005), s. 280-289 ISSN 0023-432X R&D Projects: GA ČR(CZ) GA106/02/0584 Institutional research plan: CEZ:AV0Z20410507 Keywords : duplex steel * fatigue life * cyclic plasticity Subject RIV: JG - Metallurgy Impact factor: 0.973, year: 2005

  5. A new model for fatigue damage accumulation of austenitic stainless steel under variable amplitude loading

    International Nuclear Information System (INIS)

    Taheri, S.; Vincent, L.; Le-Roux, J.C.

    2013-01-01

    The application of Miner's rule using a loading issued from a mock-up of a RHR system (removal heat system) of PWR plant, made of 304 steel gives a very important non-conservative fatigue life in strain control when strain fatigue curve is used. This result is due to the absence of sequence effect in Miner's rule. Many non linear damage accumulation models have been proposed to get a sequence effect. Shortcomings of some non linear damage accumulation models are discussed. So Smith-Watson-Topper and Fatemi-Socie criterions with a linear damage accumulation rule are then applied to experimental data. A major issue is the need for an elastic-plastic constitutive law which is difficult to propose in the presence of high cycle secondary hardening observed in austenitic stainless steels. A conservative model for fatigue damage accumulation under variable amplitude loading is then proposed for austenitic stainless steels in strain control, which does not need a constitutive law, but takes into account plasticity through cyclic strain stress curve. The model uses a linear damage accumulation rule. This model is based on the fact that for stainless steels, pre-hardening is detrimental for fatigue life in strain control, while it is beneficial in stress control. In the presence of low mean stress, the model is approved based on a large number of tests. Moreover the model allows to explain the larger detrimental effect of a tension mean stress in strain control tests than in stress control tests. (authors)

  6. Crack Growth Behaviour of P92 Steel Under Creep-fatigue Interaction Conditions

    Directory of Open Access Journals (Sweden)

    JING Hong-yang

    2017-05-01

    Full Text Available Creep-fatigue interaction tests of P92 steel at 630℃ under stress-controlled were carried out, and the crack propagation behaviour of P92 steel was studied. The fracture mechanism of crack growth under creep-fatigue interaction and the transition points in a-N curves were analyzed based on the fracture morphology. The results show that the fracture of P92 steel under creep-fatigue interaction is creep ductile fracture and the (Ctavg parameter is employed to demonstrate the crack growth behaviour; in addition, the fracture morphology shows that the crack growth for P92 steel under creep-fatigue interaction is mainly caused by the nucleation and growth of the creep voids and micro-cracks. Furthermore, the transition point of a-lg(Ni/Nf curve corresponds to the turning point of initial crack growth changed into steady crack growth while the transition point of (da/dN-N curve exhibits the turning point of steady creep crack growth changed into the accelerated crack growth.

  7. Experimental Study of Interactions Between Sub-oxidized Corium and Reactor Vessel Steel

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Granovsky, V.S.; Krushinov, E.V.; Vitol, S.A.; Gusarov, V.V.; Almiashev, V.I.; Lopukh, D.B.; Tromm, W.; Miassoedov, A.; Bottomley, D.; Fischer, M.; Piluso, P.; Altstadt, E.; Willschutz, H.G.; Fichoti, F.

    2006-01-01

    One of the critical factors in the analysis of in-vessel melt retention is the vessel strength. It is, in particular, sensitive to the thickness of intact vessel wall, which, in its turn, depends on the thermal conditions and physicochemical interactions with corium. Physicochemical interaction of prototypic UO 2 -ZrO 2 -Zr corium melt and VVER vessel steel was examined during the 2. Phase of the ISTC METCOR Project. Rasplav-3 test facility was used for conducting four tests, in which the Zr oxidation degree and interaction front temperature were varied; in one of the tests, stainless steel was added to the melt. Direct experimental measurements and post-test analyses were used for determining corrosion kinetics and maximum corrosion depth (i.e. the physicochemical impact of corium on the cooled vessel steel specimens), as well as the steel temperature conditions during the interaction, and finally the structure and composition of crystallized ingots, including the interaction zone. The minimum temperature on the interaction front boundary, which determined its final position and maximum corrosion depth was ∼ 1090 deg. C. An empirical correlation for calculation of corrosion kinetics has been derived. (authors)

  8. Ultimate limit states of steel containment vessel under earthquake loadings

    International Nuclear Information System (INIS)

    Akiyama, Hiroshi; Yuhara, Tetsuo; Shimizu, Seiichi; Hayashi, Kazutoshi; Takahashi, Tadao.

    1986-01-01

    The limit state induced by buckling of cylindrical steel structures under earthquake loadings was investigated from the standpoint of energy concept. A number of the buckling test of cylindrical steel shell structures has been made, which showed that they have a stable load-displacement relation and adequate deformation capacities beyond the buckling. The authors are proposing that the energy input imparted by strong earthquakes to buckled structures and the deformation capacity in post-buckling are suitable indices for seismic resistance of the cylindrical steel shell structures because the buckling does not cause the structure immediately to collapse in the case of such repeated loading as earthquake motions. The purpose of this study is to investigate the energy input to buckled cylindrical steel structures with an increase in the intensity of earthquake motions. A series of nonlinear dynamic analyses were performed under various types of earthquake records by using a hysteresis loop, including buckling, which was derived from the buckling tests. The limit state could be defined as the state in which the deformation of and the energy input into buckled structures increase divergently when the intensity of the earthquake excitation exceeds a certain value. The results obtained in this paper are intended to be adopted to the limit state in the post-buckling region to evaluate the margin of safety against the buckling resistance of cylindrical steel structures under strong earthquake loadings. (author)

  9. Characterization of four prestressed concrete reactor vessel liner steels

    International Nuclear Information System (INIS)

    Nanstad, R.K.

    1980-12-01

    A program of fracture toughness testing and analysis is being performed with PCRV steels for HTGRs. This report focuses on background information for the base materials and results of characterization testing, such as tensile and impact properties, chemical composition, and microstructural examination. The steels tested were an SA-508 class 1 forging, two plates of SA-537 class 1, and one plate of SA-537 class 2. Tensile requirements in effect at the time of procurement are met by all four steels. However, the SA-537 class 2 plate would not meet the minimum requirement for yield strength. Drop-weight and Charpy impact tests verified that the RT/sub NDT/ is equal to the NDT for each steel. Charpy impact energies at the NDT range from 40 J (30 ft-lb) for one heat of SA-537 class 1 to 100 J (74 ft-lb) for the SA-537 class 2 plate; upper-shelf energies range from 170 to 310 J (125 to 228 ft-lb) for the same two steels, respectively. The onset of upper-shelf energy occurred at temperatures ranging from 0 to 50 0 C

  10. Fatigue properties of type 316LN stainless steel in air and mercury

    International Nuclear Information System (INIS)

    Strizak, J.P.; Tian, H.; Liaw, P.K.; Mansur, L.K.

    2005-01-01

    An extensive fatigue testing program on 316LN stainless steel was recently carried out to support the design of the mercury target container for the spallation neutron source (SNS) that is currently under construction at the Oak Ridge National Laboratory in the United States. The major objective was to determine the effects of mercury on fatigue behavior. The S-N fatigue behavior of 316LN stainless steel is characterized by a family of bilinear fatigue curves which are dependent on frequency, environment, mean stress and cold work. Generally, fatigue life increases with decreasing stress and levels off in the high cycle region to an endurance limit below which the material will not fail. For fully reversed loading as well as tensile mean stress loading conditions mercury had no effect on endurance limit. However, at higher stresses a synergistic relationship between mercury and cyclic loading frequency was observed at low frequencies. As expected, fatigue life decreased with decreasing frequency, but the response was more pronounced in mercury compared with air. As a result of liquid metal embrittlement (LME), fracture surfaces of specimens tested in mercury showed widespread brittle intergranular cracking as opposed to typical transgranular cracking for specimens tested in air. For fully reversed loading (zero mean stress) the effect of mercury disappeared as frequency increased to 10 Hz. For mean stress conditions with R-ratios of 0.1 and 0.3, LME was still evident at 10 Hz, but at 700 Hz the effect of mercury had disappeared (R 0.1). Further, for higher R-ratios (0.5 and 0.75) fatigue curves for 10 Hz showed no environmental effect. Finally, cold working (20%) increased tensile strength and hardness, and improved fatigue resistance. Fatigue behavior at 10 and 700 Hz was similar and no environmental effect was observed

  11. Fatigue properties of type 316LN stainless steel in air and mercury

    Science.gov (United States)

    Strizak, J. P.; Tian, H.; Liaw, P. K.; Mansur, L. K.

    2005-08-01

    An extensive fatigue testing program on 316LN stainless steel was recently carried out to support the design of the mercury target container for the spallation neutron source (SNS) that is currently under construction at the Oak Ridge National Laboratory in the United States. The major objective was to determine the effects of mercury on fatigue behavior. The S- N fatigue behavior of 316LN stainless steel is characterized by a family of bilinear fatigue curves which are dependent on frequency, environment, mean stress and cold work. Generally, fatigue life increases with decreasing stress and levels off in the high cycle region to an endurance limit below which the material will not fail. For fully reversed loading as well as tensile mean stress loading conditions mercury had no effect on endurance limit. However, at higher stresses a synergistic relationship between mercury and cyclic loading frequency was observed at low frequencies. As expected, fatigue life decreased with decreasing frequency, but the response was more pronounced in mercury compared with air. As a result of liquid metal embrittlement (LME), fracture surfaces of specimens tested in mercury showed widespread brittle intergranular cracking as opposed to typical transgranular cracking for specimens tested in air. For fully reversed loading (zero mean stress) the effect of mercury disappeared as frequency increased to 10 Hz. For mean stress conditions with R-ratios of 0.1 and 0.3, LME was still evident at 10 Hz, but at 700 Hz the effect of mercury had disappeared ( R = 0.1). Further, for higher R-ratios (0.5 and 0.75) fatigue curves for 10 Hz showed no environmental effect. Finally, cold working (20%) increased tensile strength and hardness, and improved fatigue resistance. Fatigue behavior at 10 and 700 Hz was similar and no environmental effect was observed.

  12. Effect of test temperature on the fatigue strength of the 12GN2MFAYu tempered steel

    International Nuclear Information System (INIS)

    Goritskij, V.M.; Terent'ev, V.F.; Bobyleva, L.A.

    1979-01-01

    The cyclic strength, variation of dislocation structure and fractography of specimen fractures were investigated depending on testing temperature. The specimens were tested at temperatures of 20, 350, 450, 550 deg C. The increase of testing temperature, according to the experimental data obtained, is accompanied by an insignificant reduction of fatigue strength. The testing temperature in the range from 350 to 550 deg C has a weak effect on the fatigue strength of the quenched and tempered steel. A change in the dislocation structure occurs under all tested temperatures in the 12 GN2MFAYu steel during fatigue. The intensity of the rearrangement of dislocation structure increases as the testing temperature increases to 550 deg C causing a decrease of the limited life-time at increased stress amplitudes

  13. Effect of hot dip galvanization on the fatigue strength of steel bolted connections

    Directory of Open Access Journals (Sweden)

    S.M.J. Razavi

    2017-07-01

    Full Text Available Hot dip galvanized steel bolted joints has been tested under fatigue loading to evaluate the effect of galvanizing coating on the fatigue strength of S355 structural steel. The experimental results showed that the decrease of the fatigue life of coated specimens in comparison with that of uncoated joints is very limited and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for coating and preparation of the bolted joints is described in detail in this paper providing a useful tool for engineers involved in similar practical applications. The experimental results are compared with the previously published data on central hole notched galvanized and not treated specimens characterized by the same geometry.

  14. Electrochemical behaviour of a stainless steel coating after thermal fatigue and thermal shocks

    International Nuclear Information System (INIS)

    Boudebane, A.; Darsouni, A.; Chadli, H.; Boudebane, S.

    2012-01-01

    This work aims to study of the influence of thermal fatigue and thermal shock on the corrosion behaviour of coated steel AISI 304L. The coating was welded by TIG welding on specimens in ferritic-pearlitic steel grade AISI 4140. The study concerns three different states of deposit: sensitized, sensitized and strain hardened in surface and no sensitized. We realized electrochemical corrosion in an aqueous solution of NaCl 34 g/l. The corrosion of the specimens were evaluated by comparing the potentiodynamic curves for different states of the coating. Firstly, electrochemical characterization of deposits has shown a localized intergranular corrosion. Furthermore, the increase in the number of cycles of thermal fatigue accelerates the dissolution of deposit. Thermal shocks tend to improve resistance to corrosion. Against, the mechanical treatment of surfaces by burnishing decreases the dissolution rate of deposit cycles in thermal fatigue. (authors)

  15. Wind-Induced Fatigue Analysis of High-Rise Steel Structures Using Equivalent Structural Stress Method

    Directory of Open Access Journals (Sweden)

    Zhao Fang

    2017-01-01

    Full Text Available Welded beam-to-column connections of high-rise steel structures are susceptive to fatigue damage under wind loading. However, most fatigue assessments in the field of civil engineering are mainly based on nominal stress or hot spot stress theories, which has the disadvantage of dependence on the meshing styles and massive curves selected. To address this problem, in this paper, the equivalent structural stress method with advantages of mesh-insensitive quality and capability of unifying different stress-life curves (S-N curves into one is introduced to the wind-induced fatigue assessment of a large-scale complicated high-rise steel structure. The multi-scale finite element model is established and the corresponding wind loading is simulated. Fatigue life assessments using equivalent structural stress method, hot spot stress method and nominal stress method are performed, and the results are verified and comparisons are made. The mesh-insensitive quality is also verified. The results show that the lateral weld toe of the butt weld connecting the beam flange plate and the column is the location where fatigue damage most likely happens. Nominal stress method considers fatigue assessment of welds in a more global way by averaging all the stress on the weld section while in equivalent structural stress method and hot spot method local stress concentration can be taken into account more precisely.

  16. Effects of environment on the low-cycle fatigue behavior of Type 304 stainless steel

    International Nuclear Information System (INIS)

    Maiya, P.S.; Burke, W.F.

    1979-12-01

    The low-cycle fatigue behavior of Type 304 stainless steel has been investigated at 593 0 C in a dynamic vacuum of better than 1.3 x 10 -6 Pa (10 -8 torr). The results concerning the effects of strain range, strain rate and tensile hold time on fatigue life are presented and compared with results of similar tests performed in air and sodium environments. Under continuous symmetrical cycling, fatigue life is significantly longer in vacuum than in air; in the low strain range regime, the effect of sodium on fatigue life appears to be similar to that of vacuum. Strain rate (or frequency) strongly influences fatigue life in both air and vacuum. In compressive hold-time tests, the effect of environment on life is similar to that in a continuous-cycling test. However, tensile hold times are nearly as damaging in vacuum as in air. Thus, at least for austenitic stainless steels, the influence of the environment of fatigue life appears to depend on the loading waveshape

  17. Ultrasonic stress evaluation through thickness of a stainless steel pressure vessel

    International Nuclear Information System (INIS)

    Javadi, Yashar; Pirzaman, Hamed Salimi; Raeisi, Mohammadreza Hadizadeh; Najafabadi, Mehdi Ahmadi

    2014-01-01

    This paper investigates ultrasonic method in stress measurement through thickness of a pressure vessel. Longitudinal critically refracted (L CR ) waves are employed to measure the welding residual stresses in a vessel constructed from austenitic stainless steel 304L. The acoustoelastic constant is measured through a hydro test to keep the pressure vessel intact. Hoop and axial residual stresses are evaluated by using different frequency range of ultrasonic transducers. The welding processes of vessel shell and caps are simulated by a 3D finite element (FE) model which is validated by hole-drilling method. The residual stresses calculated by FE simulation are then compared with those obtained from the ultrasonic measurement while a good agreement is observed. It is demonstrated that the residual stresses through thickness of the stainless steel pressure vessel can be evaluated by combining FE and L CR method (known as FEL CR method). - Highlights: • The main goal is ultrasonic evaluation of through thickness stresses. • Welding processes of a stainless steel pressure vessel are modelled by FE. • The hole-drilling method is used to validate the FE results. • Residual stresses are measured by four different series of ultrasonic transducers. • The comparison between ultrasonic and FE results show an acceptable agreement

  18. Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

    Directory of Open Access Journals (Sweden)

    Abdalla Antonio J.

    2018-01-01

    Full Text Available In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a using low-power laser CO2 (125 W for introducing carbon into the surface and (b plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

  19. Low Cycle Fatigue Behaviour of DP Steels: Micromechanical Modelling vs. Validation

    Directory of Open Access Journals (Sweden)

    Ghazal Moeini

    2017-07-01

    Full Text Available This study aims to simulate the stabilised stress-strain hysteresis loop of dual phase (DP steel using micromechanical modelling. For this purpose, the investigation was conducted both experimentally and numerically. In the experimental part, the microstructure characterisation, monotonic tensile tests and low cycle fatigue tests were performed. In the numerical part, the representative volume element (RVE was employed to study the effect of the DP steel microstructure of the low cycle fatigue behavior of DP steel. A dislocation-density based model was utilised to identify the tensile behavior of ferrite and martensite. Then, by establishing a correlation between the monotonic and cyclic behavior of ferrite and martensite phases, the cyclic deformation properties of single phases were estimated. Accordingly, Chaboche kinematic hardening parameters were identified from the predicted cyclic curve of individual phases in DP steel. Finally, the predicted hysteresis loop from low cycle fatigue modelling was in very good agreement with the experimental one. The stabilised hysteresis loop of DP steel can be successfully predicted using the developed approach.

  20. Application of the master curve approach to fracture mechanics characterisation of reactor pressure vessel steel

    International Nuclear Information System (INIS)

    Viehrig, Hans-Werner; Zurbuchen, Conrad; Kalkhof, Dietmar

    2010-06-01

    The paper presents results of a research project founded by the Swiss Federal Nuclear Inspectorate concerning the application of the Master Curve approach in nuclear reactor pressure vessels integrity assessment. The main focus is put on the applicability of pre-cracked 0.4T-SE(B) specimens with short cracks, the verification of transferability of MC reference temperatures T 0 from 0.4T thick specimens to larger specimens, ascertaining the influence of the specimen type and the test temperature on T 0 , investigation of the applicability of specimens with electroerosive notches for the fracture toughness testing, and the quantification of the loading rate and specimen type on T 0 . The test material is a forged ring of steel 22 NiMoCr 3-7 of the uncommissioned German pressurized water reactor Biblis C. SE(B) specimens with different overall sizes (specimen thickness B=0.4T, 0.8T, 1.6T, 3T, fatigue pre-cracked to a/W=0.5 and 20% side-grooved) have comparable T 0 . T 0 varies within the 1σ scatter band. The testing of C(T) specimens results in higher T 0 compared to SE(B) specimens. It can be stated that except for the lowest test temperature allowed by ASTM E1921-09a, the T 0 values evaluated with specimens tested at different test temperatures are consistent. The testing in the temperature range of T 0 ± 20 K is recommended because it gave the highest accuracy. Specimens with a/W=0.3 and a/W=0.5 crack length ratios yield comparable T 0 . The T 0 of EDM notched specimens lie 41 K up to 54 K below the T 0 of fatigue pre-cracked specimens. A significant influence of the loading rate on the MC T 0 was observed. The HSK AN 425 test procedure is a suitable method to evaluate dynamic MC tests. The reference temperature T 0 is eligible to define a reference temperature RT To for the ASME-KIC reference curve as recommended in the ASME Code Case N-629. An additional margin has to be defined for the specific type of transient to be considered in the RPV integrity assessment

  1. Creep-fatigue evaluation method for modified 9Cr-1Mo steel

    International Nuclear Information System (INIS)

    Wada, Y.; Aoto, K.

    1997-01-01

    As creep-fatigue evaluation methods on normalized and tempered Modified 9Cr-1Mo steel for design use, the time fraction rule and the simplified conventional ductility exhaustion rule are investigated for the prediction of tension strain hold creep-fatigue damage of this material. For the above investigation, stress relaxation behaviour during strain hold has to be analyzed using stress-strain-time relation. The initial value of stress relaxation was determined by cyclic stress-strain curves in continuous cycling fatigue tests. Cyclic stress-strain behaviour of Mod.9Cr-1Mo(NT) steel is different from that of austenitic stainless steels, so this effect was considered. Stress relaxation analysis was performed using static creep strain-time relation and conventional hardening rule. The time fraction by using the above stress relaxation analysis results can give good prediction for creep-fatigue life of Mod.9Cr-1Mo(NT) steel. For design use it is practical to be able to estimate creep damages conservatively by both strain behaviour of cyclic plastic (in continuous cycling fatigue tests) and monotonic creep (in standard creep tests). The life reduction by strain hold at the minimum peak of compressive stress in creep-fatigue tests was examined, and this effects can be evaluated by the relationship between the location of oxidation and the effective deformation at crack tip. In an accelerated oxidation environment, for example in high temperature and high pressure steam, a different approach for life reduction should be developed based on the mechanism of growth of oxide and crack growth with oxidation. However, in the creep damage dominant region, its effect is saturated and the effect of cavity growth along grain boundary becomes dominant for long-term strain hold in the high temperature conditions. (author). 6 refs, 6 figs

  2. Influence of microstructure on low cycle fatigue in some single phase and biphasic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Stolarz, J. [Ecole Nationale Superieure des Mines, Centre SMS, URA CNRS 1884, Saint-Etienne (France)

    2004-07-01

    This overview deals with the effects of microstructural parameters in different single phase and biphasic stainless steels on short crack behaviour and on fatigue life in the low cycle regime. The effect of the grain size is investigated in a single phase austenitic stainless steel. Under plastic strain control, the fatigue life increases when the grain size decreases. The results are discussed by analysing the distributions of crack depths as a function of the grain size. The second type of material is a metastable austenitic steel which partially transforms into martensite during LCF at temperatures between -50 C and +120 C. The grain size of the initially single phase austenitic microstructure has a combined influence on the volume fraction of martensite produced during fatigue and on the fatigue life. In this case, the grain size effect is still considerable but totally indirect because all fatigue cracks grow exclusively in the martensite. The cyclic behaviour analysis in biphasic alloys in which two phases undergo plastic deformation during LCF is considerably more complex because the conventional concept of microstructural barriers cannot be applied. The possible damage patterns in a pair of grains with different mechanical properties are discussed on the example of a solution treated and aged superduplex austenitic-ferritic stainless steel (SDSS). The hardening of one phase (ferrite) through ageing at 475 C changes the cyclic behaviour of the initial ''quasi single phase'' microstructure. Consequently, the fatigue life under plastic strain control decreases compared with the solution treated SDSS. The discussion is focussed on LCF damage mechanisms at the microstructure size scale with a particular accent put on the propagation of short cracks in the bulk. All the microstructures exhibit some common features with respect to the behaviour of short cracks. In particular a strong effect of microstructural barriers in the bulk and the

  3. Effect of laser shock processing on fatigue crack growth of duplex stainless steel

    International Nuclear Information System (INIS)

    Rubio-Gonzalez, C.; Felix-Martinez, C.; Gomez-Rosas, G.; Ocana, J.L.; Morales, M.; Porro, J.A.

    2011-01-01

    Research highlights: → LSP is an effective surface treatment to improve fatigue properties of duplex stainless steel. → Increasing pulse density, fatigue crack growth rate is reduced. → Microstructure is not affected by LSP. → Compressive residual stresses increases increasing pulse density. - Abstract: Duplex stainless steels have wide application in different fields like the ship, petrochemical and chemical industries that is due to their high strength and excellent toughness properties as well as their high corrosion resistance. In this work an investigation is performed to evaluate the effect of laser shock processing on some mechanical properties of 2205 duplex stainless steel. Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switched Nd:YAG laser, operating at 10 Hz with infrared (1064 nm) radiation. The pulses are focused to a diameter of 1.5 mm. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is determined by the contour method. It is observed that the higher the pulse density the greater the compressive residual stress. Pulse densities of 900, 1600 and 2500 pul/cm 2 are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness if this steel.

  4. The Effect of Hold Time on Creep-Fatigue in 9Cr-1Mo

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Tae Young; Kim, Dae Whan; Kim, Yong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Baek, Kyoung Ho [Chungnam National University, Daejeon (Korea, Republic of)

    2009-05-15

    9Cr-1Mo steel is a candidate material for reactor vessel for VHTR. Because 9Cr-1Mo steel has a good mechanical properties and a lower thermal expansion coefficient than austenitic stainless steel. The reactor vessel of VHTR is operated at about 450 .deg. C. At this temperature, fatigue occurs during start-up and cool-down, and creep occurs during normal operation. Creep-fatigue damage by the interaction between fatigue and creep is an important factor that limits VHTR reactor vessel life. In this study, Effect of hold time on low cycle fatigue behavior of 9Cr-1Mo at 600 .deg. C was investigated in air.

  5. The Effect of Hold Time on Creep-Fatigue in 9Cr-1Mo

    International Nuclear Information System (INIS)

    Oh, Tae Young; Kim, Dae Whan; Kim, Yong Wan; Baek, Kyoung Ho

    2009-01-01

    9Cr-1Mo steel is a candidate material for reactor vessel for VHTR. Because 9Cr-1Mo steel has a good mechanical properties and a lower thermal expansion coefficient than austenitic stainless steel. The reactor vessel of VHTR is operated at about 450 .deg. C. At this temperature, fatigue occurs during start-up and cool-down, and creep occurs during normal operation. Creep-fatigue damage by the interaction between fatigue and creep is an important factor that limits VHTR reactor vessel life. In this study, Effect of hold time on low cycle fatigue behavior of 9Cr-1Mo at 600 .deg. C was investigated in air

  6. Probabilistic evaluation of fatigue crack growth in SA 508 and SA 533 B steel

    International Nuclear Information System (INIS)

    Dufresne, J.; Rieunier, J.B.

    1982-07-01

    This paper describes the method used to select the best representative law of fatigue crack growth in view of its introduction in a probabilist computer code). A modelling of the selected law (Paris law) and the statistical distribution of the corresponding numerical coefficients are presented. Results of computation are given in the case of a PWR pressure vessel with defects in belt line weld

  7. X-ray fractography on fatigue fracture surface of high manganese austenitic steel

    International Nuclear Information System (INIS)

    Akita, Koichi; Misawa, Hiroshi; Kodama, Shotaro; Saito, Tetsuro.

    1997-01-01

    Fatigue tests were carried out under constant stress amplitude, using a non-magnetic high manganese Mn-Cr steel. X-ray fractography was applied on the fatigue fractured surface to investigate the relationship between stress intensity factor and residual stress or half-value breadth of the X-ray diffraction profile. The fatigue crack propagation rate of this non-magnetic Mn-Cr steel had the same tendency as in the ordinary structural ferritic steels. The relationship between stress intensity factor and the residual stress or half-value breadth of the steel was almost the same as that of the ferritic cyclic work hardening steels. No stress induced transformation was observed on the fracture surface, but the residual stress on the fractured surface was compressive in the high stress intensity factors range, which is typical in the cyclic work hardening steels. The half-value breadth on the fractured surface increased with increasing effective stress intensity factor range. The relationship between the half-value breadth and stress intensity factor range was represented by a linear line regardless of the stress ratio. Therefore, the acting stress intensity factor range at the time of fracture can be estimated from the half-value breadth. The depth of monotonic plastic zone was estimated from the distribution of half-value breadth beneath the fractured surface. The relationship between the maximum stress intensity factor and half-value breadth was expressed by the equation ω m α(K max /σ y ) 2 , where the value of α was 0.025. This is about one sixth of the value for ferritic steels, and the fact shows the severe work hardening occuring in the plastic zone in this manganese steel. (author)

  8. High-cycle fatigue characteristics of weldable steel for light-water reactors

    International Nuclear Information System (INIS)

    Klesnil, M.; Polak, J.; Obrtlik, K.; Troshchenko, V.T.; Mishchenko, Yu.I.; Khamaza, L.A.

    1982-01-01

    Czechoslovak and Soviet 15Kh2NMFA steel was used for running fatigue tests at temperatures of 20, 350 and 400 degC in the high-cycle range with various loading regimes. The results show that at the given temperatures in this type of steel a cyclic softening occurs. The fatigue characteristics were measured with great dispersion of results, but within this dispersion they are almost identical for various steels at the same temperature. Increased temperature results in the decrease in the amplitude of cyclic deformation stress and in the increase in the amplitude of plastic deformation. The diversity in the values of cyclic plasticity and stress response measured in the given mode may be explained by the lower level of softening and the non-homogeneous cyclic plastic deformation of material under the given constant conditions. (J.B.)

  9. Study of the corrosion fatigue resistance of steel grades for automotive suspension springs

    Energy Technology Data Exchange (ETDEWEB)

    Mougin, J. [Ascometal CREAS, BP70045, F-57301 Hagondange Cedex (France); Mostacchi, A. [Ascometal Developpement, BP17, F-38570 Le Cheylas (France); Hersart, Y. [Allevard Rejna Autosuspensions CRDT, 201 Rue de Sin-le-Noble, BP629, F-59506 Douai Cedex (France)

    2004-07-01

    In order to reduce the total weight of vehicles for ecological and economical reasons, the car makers use down-sizing for several components of the cars. Concerning helical suspension springs, the size of the bar diameter and the number of spring coils are decreased, leading to an increase of the stress level applied on the spring. In this respect, steels with high mechanical properties are required, to achieve a good fatigue resistance of the springs. The corrosion resistance is also important for this application. Indeed, during service, the protective coating applied on the springs can be scratched by gravels, and bare underlying metal can be put in contact with the atmosphere, including humidity, drops of rain but also de-icing salts. Generally speaking, an increase of mechanical properties decreases the corrosion fatigue resistance of the steels. In this respect, a compromise needs to be found, that is why the study of corrosion fatigue resistance is very important. In order to study the corrosion fatigue resistance of spring steels, an original device and test procedure have been set up. Torsional fatigue on specimens is used to simulate the stress applied on each spring coil. The stress levels are chosen to be representative of the actual inservice loads. The specimens are shot-peened and coated in a same way as the actual springs. Scratching of the painting is performed, giving rise to small areas of bare metal. Three types of tests are performed: fatigue in air (taken as the reference level), fatigue on specimens which have been corroded previously (test similar to the spring-makers practice) and coupled corrosion fatigue. The mechanisms involved in corrosion fatigue have been studied. For all the specimens, crack initiated on corrosion pits. For the specimens corroded prior fatigue testing, the corrosion pits can be quite severe. In this case, these pits act as a surface defect which increases locally the stress concentration and accelerates the crack

  10. Creep and creep fatigue crack behavior of 1Cr- and 9Cr-steels

    International Nuclear Information System (INIS)

    Maile, K.; Klenk, A.; Schellenberg, G.; Granacher, J.; Tramer, M.

    2000-01-01

    A large database for creep crack initiation and propagation under constant load conditions is available on conventional power plant steels of types 1%Cr and 12%Cr. Modern plants are often used in the medium and peak load regime, thus the dominant loading situation in high temperature components is creep fatigue. For life assessment data about crack initiation and growth under creep fatigue loading are required. These characteristics can not be substituted by pure fatigue or creep crack data. Therefore, a comprehensive test programme was started to investigate the creep fatigue crack behaviour of a 1%CrMoNiV turbine rotor steel (30CrMoNiV 4 11) at 550 C and a new 9%CrMoVNb pipe steel (type P 9 1) at 600 C. DENT-specimen with 15 and 60 mm thickness as well as side grooved CT-specimen with 25 and 50 mm thickness have been tested to determine possible influences of geometry and thus to check the transferability of the data to components. The creep fatigue crack growth results of tests with dwell times between t H = 0,32h and 10 h lie in the scatterbands given by creep crack growth results. Nevertheless a higher crack growth rate under creep fatigue conditions can be stated. An increase in crack growth rate due to creep fatigue is clearly visible. Loading situations with frequencies higher than 1.10 -4 Hz should be not assessed with pure creep crack results or sufficient safety margins have to be applied. (orig.)

  11. High Cycle Fatigue of Metastable Austenitic Stainless Steels

    OpenAIRE

    Fargas Ribas, Gemma; Zapata Dederle, Ana Cristina; Anglada Gomila, Marcos Juan; Mateo García, Antonio Manuel

    2009-01-01

    Metastable austenitic stainless steels are currently used in applications where severe forming operations are required, such as automotive bodies, due to its excellent ductility. They are also gaining interest for its combination of high strength and formability after forming. The biggest disadvantage is the difficulty to predict the mechanical response, which depends heavily on the amount of martensite formed. The martensitic transformation in metastable stainless steels can b...

  12. Effects of pulse current stimulation on the thermal fatigue crack propagation behavior of CHWD steel

    International Nuclear Information System (INIS)

    Lin, H.Q.; Zhao, Y.G.; Gao, Z.M.; Han, L.G.

    2008-01-01

    The fatigue crack propagating behaviors of cast hot working die (CHWD) steel untreated and treated by an electric current in the intermediate stage of thermal fatigue were investigated in the present study. The circle/elliptical heating affected zone (HAZ) was formed ahead of the notch tip on the fatigued specimens after pulse electric current stimulation. Both SEM observation and X-ray diffraction analysis revealed that pulse electric current stimulation refined grains/subgrains in the HAZs. With the prolonging of discharging duration, the grains/subgrains decreased in size and the dislocation density and microhardness increased gradually. The grain refinement and dislocation density increase played an important role in the material strengthening, which inevitably enhanced the propagation resistance and delayed the propagation of thermal fatigue cracks. Therefore, the pulse electric current stimulation was an effective method to improve the service lifetime of die material

  13. Interaction of high cycle fatigue and creep in 9%Cr-1%Mo steel at elevated temperature

    International Nuclear Information System (INIS)

    Vasina, R.; Lukas, P.; Kunz, L.; Sklenicka, V.

    1995-01-01

    High-cycle-fatigue/creep experiments were performed on a 9%Cr-1%Mo tempered martensite ferritic steel at 873 K in air. The stress ratio R = σ min /σ max ranged from -1 (''pure'' fatigue) to 1 (''pure'' creep). The maximum stress σ max was kept constant at 240 MPa.The lifetime depends on the stress ratio R in a non-monotonic way. In the stress ratio interval 0.6 mean of the stress cycle. In the stress ratio interval -1 a . The fatigue/creep interaction occurs in between these intervals. The fatigue/creep loading induces transformation of the tempered martensite ferritic structure into an equiaxed subgrain structure. The resulting subgrain size depends strongly on the stress ratio. (author)

  14. Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

    International Nuclear Information System (INIS)

    Magnier-Monin, L.

    2007-12-01

    This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)

  15. Effects of lithium environment on the fatigue properties of ferritic and austenitic steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Smith, D.L.

    1982-01-01

    Low-cycle fatigue data have been obtained on HT-9 alloy and Type 304 stainless steel at 755 K in a flowing lithium environment of controlled purity. The results show that the fatigue properties of these materials are strongly influenced by the concentration of nitrogen in lithium. For HT-9 alloy, the fatigue life in lithium containing 1000-1500 wppm nitrogen is a factor of 2 to 5 lower than that in lithium with 100-200 wppm nitrogen. The reduction in fatigue life in high-nitrogen lithium can be attributed to internal corrosive attack of the material. The specimens tested in high-nitrogen lithium show considerable surface corrosion, internal corrosive attack, secondary cracks, and partial intergranular fracture mode. This behavior is not observed in specimens tested either in low-nitrogen lithium or a sodium environment. (orig.)

  16. Fatigue crack propagation of super duplex stainless steel and time-frequency analysis of acoustic emission

    International Nuclear Information System (INIS)

    Lee, Sang Kee; Nam, Ki Woo; Kang, Chang Yong; Do, Jae Yoon

    2000-01-01

    On this study, the fatigue crack propagation of super duplex stainless steel is investigated in conditions of various volume fraction of austenite phase by changing heat treatment temperature. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis methods. As the temperature of heat treatment increased, volume fraction of austenite decreased and coarse grain was obtained. The specimen heat treated at 1200 deg. C had longer fatigue life and slower rate of crack growth. As a result of time-frequency analyze of acoustic emission signals during fatigue test, main frequency was 200∼300 kHz having no correlation with heat treatment and crack length, and 500 kHz was obtained by dimple and separate of inclusion

  17. Acoustic emission test on a 25mm thick mild steel pressure vessel with inserted defects

    International Nuclear Information System (INIS)

    Bentley, P.G.; Dawson, D.G.; Hanley, D.J.; Kirby, N.

    1976-12-01

    Acoustic emission measurements have been taken on an experimental mild steel vessel with 4 inserted defects ranging in severity up to 90% of through thickness. The vessel was subjected to a series of pressure excursions of increasing magnitude until failure occurred by extension of the largest inserted defect through the vessel wall. No acoustic emission was detected throughout any part of the tests which would indicate the presence of such serious defects or of impending failure. Measurements of acoustic emission from metallurgical specimens are included and the results of post test inspection using conventional NDT and metallographic techniques are reported. (author)

  18. Pressure vessels for reactors made from structural steel with limited tensile strength

    International Nuclear Information System (INIS)

    Machatti, H.

    1973-01-01

    The reactor pressure vessel is prestressed in several directions with prestressing elements fabricated of steel with a high yielding point. This design allows a substantial reduction of wall thickness or an increase of the inner diameter at equal wall thickness. The prestress of the prestressing elements is designed to achieve a maximum stress release of the vessel walls at normal operating conditions and to fully utilize the maximum load of the vessel walls. For safety reasons the cross section of the prestressing elements is constructed in a way that strain is always 20 % lower the yield point. (P.K.)

  19. Influence of heat treatments on thermoelectric power of pressure vessel steels: effect of microstructural evolutions of strongly segregated areas

    International Nuclear Information System (INIS)

    Houze, M.

    2002-12-01

    Thermoelectric power measurement (TEP) is a very potential non destructive evaluation method considered to follow ageing under neutron irradiation of pressure vessel steel of nuclear reactor. Prior to these problems, the aim of this study is to establish correlations between TEP variations and microstructural evolutions of pressure vessel steels during heat treatments. Different steels, permitting to simulate heterogeneities of pressure vessel steels and to deconvoluate main metallurgical phenomenons effects were studied. This work allowed to emphasize effect on TEP of: austenitizing and cooling conditions and therefore of microstructure, metallurgical transformations during tempering (recovery, precipitation of alloying elements), and particularly molybdenum precipitation associated to secondary hardening, residual austenite amount or partial austenitizing. (author)

  20. Identification of low cycle fatigue parameters of high strength low-alloy (HSLA steel at room temperature

    Directory of Open Access Journals (Sweden)

    S. Bulatović

    2014-10-01

    Full Text Available Low cycle fatigue test was performed in ambient atmosphere at room temperature. Cycle loading of material, in case of High strength low-alloy steel, entails modifications of its properties and in this paper is therefore shown behavior of fatigue life using low cycle fatigue parameters. More precisely, crack initiation life of tested specimens was computed using theory of Coffin-Manson relation during the fatigue loading. The geometry of the stabilized hysteresis loop of welded joint HSLA steel, marked as Nionikral 70, is also analyzed. This stabilized hysteresis loop is very important for determination of materials properties.

  1. Fatigue Life of Stainless Steel in PWR Environments with Strain Holding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taesoon; Kim, Kyuhyung [KHNP CRI, Daejeon (Korea, Republic of); Seo, Myeonggyu; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    Many components and structures of nuclear power plants are exposed to the water chemistry conditions during the operation. Recently, as design life of nuclear power plant is expanded over 60 years, the environmentally assisted fatigue (EAF) due to these water chemistry conditions has been considered as one of the important damage mechanisms of the safety class 1 components. Therefore, many studies to evaluate the effect of light water reactor (LWR) coolant environments on fatigue life of materials have been conducted. Many EAF test results including Argonne National Laboratory’s consistently indicated the substantial reduction of fatigue life in the light water reactor environments. However, there is a discrepancy between laboratory test data and plant operating experience regarding the effects of environment on fatigue: while laboratory test data suggest huge accumulation of fatigue damage, very limited experience of cracking caused by the low cycle fatigue in light water reactor. These hold-time effect tests are preformed to characterize the effects of strain holding on the fatigue life of austenitic stainless steels in PWR environments in comparison with the existing fixed strain rate results. Low cycle fatigue life tests were conducted for the type 316 stainless steel in 310℃ air and PWR environments with triangular strain. In agreement with the previous reports, the LCF life was reduced in PWR environments. Also for the slower strain rate, the reduction of LCF life was greater than the faster strain rate. The LCF test conditions for the hold-time effects were determined by the references and consideration of actual plant transient. To simulate the heat-up and cooldown transient, sub-peak strain holding during the down-hill of strain amplitude was chosen instead of peak strain holding which used in the previous researches.

  2. Fatigue crack growth retardation in spot heated mild steel sheet

    Indian Academy of Sciences (India)

    A fatigue crack can be effectively retarded by heating a spot near the crack tip under nil remote stress condition. The subcritical spot heating at a proper position modifies the crack growth behaviour in a way, more or less, similar to specimen subjected to overload spike. It is observed that the extent of crack growth retardation ...

  3. Corrosion fatigue crack growth behaviour of low-alloy RPV steels at different temperatures and loading frequencies under BWR/NWC environment

    International Nuclear Information System (INIS)

    Ritter, S.; Seifert, H.P.

    2004-01-01

    The strain-induced corrosion cracking or low-frequency corrosion fatigue (LFCF) crack growth behaviour of different reactor pressure vessel (RPV) steels and of a RPV weld filler/weld heat-affected zone (HAZ) material were characterized under simulated transient boiling water reactor/normal water chemistry conditions by cyclic fatigue tests with pre-cracked fracture mechanics specimens. The experiments were performed in oxygenated high-temperature water at temperatures of either 288, 250, 200, or 150 deg. C. Modern high-temperature water loops, on-line crack growth monitoring (DCPD) and fractographic analysis by SEM were used to quantify the cracking response. Under low-flow and highly oxidising conditions (ECP > 0 mV SHE , O 2 = 0.4 ppm) the cycle-based LFCF crack growth rates (CGR) Δa/ΔN increased with decreasing loading frequency and increasing temperature with a maximum/plateau at/above 250 deg. C. Sustained environmentally-assisted crack growth could be maintained down to low frequencies of 10 -5 Hz. The LFCF CGR of low- and high-sulphur steels and of the weld filler/HAZ material were comparable over a wide range of loading conditions and conservatively covered by the 'high-sulphur line' of the General Electric-model. The 'ASME XI wet fatigue CGR curves' could be significantly exceeded in all materials by cyclic fatigue loading at low frequencies ( -2 Hz) at high and low load ratios R. (authors)

  4. Study of cladding toughness in a pressure vessel steel water reactor

    International Nuclear Information System (INIS)

    Soulat, P.; Al Mundheri, M.

    1984-12-01

    Toughness of cladding and pressure vessel steel were determined at different temperatures in order to appreciate the participation of cladding resistance against crack propagation. The toughness of cladding is comparable with typical results on austenitic welds. The test on covered CT specimens shows the possibility of having a relatively good prevision of the behaviour of a coated structure

  5. Positron annihilation and Moessbauer studies of neutron irradiated reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Brauer, G.; Matz, W.; Liszkay, L.; Molnar, B.

    1990-11-01

    Positron annihilation (lifetime, Doppler broadening) and Moessbauer studies on unirradiated, neutron irradiated and neutron irradiated plus annealed reactor pressure vessel steels (Soviet type 15Kh2NMFA) are presented. The role of microstructural properties and the formation of irradiation-induced precipitates is discussed. (orig.) [de

  6. Resistance of heat resisting steels and alloys to thermal and mechanical low-cycle fatigue

    International Nuclear Information System (INIS)

    Tulyakov, G.A.

    1980-01-01

    Carried out is a comparative evalUation of resistance of different materials to thermocyclic deformation and fracture on the base of the experimental data on thermal and mechanical low-cycle fatigUe. Considered are peculiarities of thermal fatigue resistance depending on strength and ductility of the material. It is shown, that in the range of the cycle small numbers before the fracture preference is given to the high-ductility cyclically strengthening austenitic steels of 18Cr-10Ni type with slight relation of yield strength to the σsub(0.2)/σsub(B) tensile strength Highly alloyed strength chromium-nickel steels, as well as cyclically destrengthening perlitic and ferritic steels with stronger σsub(0.2)/σsub(B) relation as compared with simple austenitic steels turn to be more long-lived in the range of the cycle great numbers berore fracture. Perlitic steels are stated to have the lowest parameter values of the K crack growth intensity under the similar limiting conditions of the experiment, while steels and alloys with austenite structure-higher values of the K parameter

  7. Study on Characteristics of Corrosion Fatigue Crack Propagation for Austenitic Stainless Steel

    International Nuclear Information System (INIS)

    Lim, Uh Joh; Kim, Bu Ahn

    1988-01-01

    The characteristics of the corrosion fatigue cracking of both TIG weld heat affected zone and base metal for austenitic stainless steel were investigated under the environments of various specific resistance and the air. The corrosion fatigue crack initiation sensitivity was quantitatively investigated for SUS 304 weldments in the various specific resistances. Also, the characteristics of corrosion fatigue cracking for the weldments were investigated from mechanical, electrochemical, and microstructural point of view. Main results obtained are as follows: (1) The corrosion fatigue crack initiation sensitivity on the base metal and weld hea affected zone increases as the specific resistance of corrosion environment decreases, and the sensitivity of the weld heat affected zone appears increasing more than that of the base metal. (2) The corrosion potentials of various specific resistances are almost constant in initial corrosion fatigue cracking, but the corrosion potential becomes less noble promptly with the corrosion fatigue crack growth as the specific resistances decrease. (3) The corrosion fatigue crack growth of the weld heat affected zone rapid than that of the base metal, because of the softening and the less noble potential caused by welding heat cycle

  8. Development of nondestructive evaluation of creep-fatigue damage in SUS316 stainless steel

    International Nuclear Information System (INIS)

    Shoji, Tetsuo; Kawahara, Tetsuji; Awano, Masakazu; Sato, Yasumoto

    1999-01-01

    Creep-fatigue is a fatal failure mode of high temperature structural materials. It is recognized that the law of linear damage, according to which creep-fatigue damage is expressed by the sum of the creep damage and the fatigue damage, is inadequate to evaluate creep-fatigue damage. This is due to the fact that the law of linear damage does not include the effect of interaction between the creep damage and the fatigue damage. Consequently, development of direct measurement of damage accumulation on the sample of interest is required for plant life evaluation. In this study, the induced current focusing potential drop (ICFPD) technique was used to evaluate the depth of small surface cracks in SUS316FR stainless steel which was subjected to creep-fatigue damage. It is shown that the potential drop increased during the micro-crack initiation and propagation. Correspondingly, the ICFPD technique applied to estimate micro-crack depth changes was used to accurately evaluate the residual life of creep-fatigue damaged structural materials. (author)

  9. Effect of surface integrity of hard turned AISI 52100 steel on fatigue performance

    International Nuclear Information System (INIS)

    Smith, Stephen; Melkote, Shreyes N.; Lara-Curzio, Edgar; Watkins, Thomas R.; Allard, Larry; Riester, Laura

    2007-01-01

    This paper addresses the relationship between surface integrity and fatigue life of hard turned AISI 52100 steel (60-62 HRC), with grinding as a benchmark. The impact of superfinishing on the fatigue performance of hard turned and ground surfaces is also discussed. Specifically, the surface integrity and fatigue life of the following five distinct surface conditions are examined: hard turned with continuous white layer, hard turned with no white layer, ground, and superfinished hard turned and ground specimens. Surface integrity of the specimens is characterized via surface topography measurement, metallography, residual stress measurements, transmission electron microscopy (TEM), and nano-indentation tests. High cycle tension-tension fatigue tests show that the presence of white layer does not adversely affect fatigue life and that, on average, the hard turned surface performs as well or better than the ground surface. The effect of superfinishing is to exaggerate these differences in performance. The results obtained from this study suggest that the effect of residual stress on fatigue life is more significant than the effect of white layer. For the hard turned surfaces, the fatigue life is found to be directly proportional to both the surface compressive residual stress and the maximum compressive residual stress. Possible explanations for the observed effects are discussed

  10. Large inelastic deformation analysis of steel pressure vessels at high temperature

    International Nuclear Information System (INIS)

    Ikonen, K.

    2001-01-01

    This publication describes the calculation methodology developed for a large inelastic deformation analysis of pressure vessels at high temperature. Continuum mechanical formulation related to a large deformation analysis is presented. Application of the constitutive equations is simplified when the evolution of stress and deformation state of an infinitesimal material element is considered in the directions of principal strains determined by the deformation during a finite time increment. A quantitative modelling of time dependent inelastic deformation is applied for reactor pressure vessel steels. Experimental data of uniaxial tensile, relaxation and creep tests performed at different laboratories for reactor pressure vessel steels are investigated and processed. An inelastic deformation rate model of strain hardening type is adopted. The model simulates well the axial tensile, relaxation and creep tests from room temperature to high temperature with only a few fitting parameters. The measurement data refined for the inelastic deformation rate model show useful information about inelastic deformation phenomena of reactor pressure vessel steels over a wide temperature range. The methodology and calculation process are validated by comparing the calculated results with measurements from experiments on small scale pressure vessels. A reasonably good agreement, when taking several uncertainties into account, is obtained between the measured and calculated results concerning deformation rate and failure location. (orig.)

  11. Applicability of JIS SPV 50 steel to primary containment vessel of nuclear power station

    International Nuclear Information System (INIS)

    Iida, Kunihiro; Ishikawa, Koji; Sakai, Keiichi; Onozuka, Masakazu; Sato, Makoto.

    1979-01-01

    The space within reactor containment vessels must be expanded in order to improve the reliability of nuclear power plants, accordingly the adoption of large reactor containment vessels is investigated. SGV 42 and 49 steels in JIS G 3118 have been used for containment vessels so far, but stress relief annealing is required when the thickness exceeds 38 mm. The time has come when the use of thicker conventional plates without stress relieving or the use of high strength steel must be examined in detail. In this study, the tests of confirming material properties were carried out on SPV 50 in JIS G 3115, Steels for pressure vessels, aiming at the method of fabrication without stress relieving. The highest and lowest temperatures in use were set at 171 deg and -8 deg C, respectively. The chemical composition and the mechanical properties of the plates tested, the method of welding, the results of tensile test on the parent metal and the welds, the required lowest preheating temperature, the fracture toughness at low temperature and the brittle fracture causing test are reported. The parent metal and the welded joints of SPV 50 have the properties suitable to reactor containment vessels, namely the sufficient fracture toughness to guarantee the prevention of unstable fracture when the method of welding without stress relieving is adopted. (Kako, I.)

  12. Lessons Learned From Developing Reactor Pressure Vessel Steel Embrittlement Database

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL

    2010-08-01

    Materials behaviors caused by neutron irradiation under fission and/or fusion environments can be little understood without practical examination. Easily accessible material information system with large material database using effective computers is necessary for design of nuclear materials and analyses or simulations of the phenomena. The developed Embrittlement Data Base (EDB) at ORNL is this comprehensive collection of data. EDB database contains power reactor pressure vessel surveillance data, the material test reactor data, foreign reactor data (through bilateral agreements authorized by NRC), and the fracture toughness data. The lessons learned from building EDB program and the associated database management activity regarding Material Database Design Methodology, Architecture and the Embedded QA Protocol are described in this report. The development of IAEA International Database on Reactor Pressure Vessel Materials (IDRPVM) and the comparison of EDB database and IAEA IDRPVM database are provided in the report. The recommended database QA protocol and database infrastructure are also stated in the report.

  13. A three-dimensional rupture analysis of steel liners anchored to concrete pressure and containment vessels

    International Nuclear Information System (INIS)

    Bangash, Y.

    1987-01-01

    Steel liners or plates are anchored to concrete pressure and containment vessels for nuclear and offshore facilities. Due to extreme loading conditions a liner may buckle due to the pull-out or shearing of anchors from the base metal and concrete. Under certain conditions attributed to loadings, liner metal deterioration and cracking of concrete behind the liner, the liner may fail by rupture. This paper presents a three-dimensional analysis of steel-concrete elements, using finite elements analysis in which a provision is made for liner instability, anchor strength and stiffness, concrete cracking and finally liner rupture. The analysis is tested first on an octagonal slab with and without an anchored steel liner. It is then extended to concrete pressure and containment vessels. The analytical results obtained are compared well with those available from the experimental tests and other sources. (author)

  14. Reduction factors for creep strength and fatigue life of modified 9 Cr-1 Mo steel weldments

    International Nuclear Information System (INIS)

    Blass, J.J.; Battiste, R.L.; O'Connor, D.G.

    1991-01-01

    The provisions of ASME B ampersand PV Code Case N-47 currently include reduction factors for creep strength and fatigue life of weldments. To provide experimental confirmation of such factors for modified 9 Cr-1 Mo steel, tests of tubular specimens were conducted at 538 degree C (1000 degree F). Three creep-rupture specimens with longitudinal welds were tested in tension; and, of three with circumferential welds, two were tested in tension and one in torsion. In each specimen with a circumferential weld, a nonuniform axial distribution of strain was easily visible. The test results were compared to an existing empirical model of creep-rupture life. For the torsion test, the comparison was based on a definition of equivalent normal stress recently adopted in Code Case N-47. Some 27 fatigue specimens, with longitudinal, circumferential, or no welds, were tested under axial or torsional strain control. In specimens with welds, fatigue cracking initiated at fusion lines. In axial tests cracks grew in the circumferential direction, and in torsional tests cracks grew along fusion lines. The test results were compared to empirical models of fatigue life based on two definition of equivalent normal strain range. The results have provided some needed confirmation of the reduction factors for creep strength and fatigue life of modified 9 Cr-1 Mo steel weldments currently under consideration by ASME Code committees. 8 refs., 5 figs

  15. Influence of the mechanical fatigue progress on the magnetic properties of electrical steel sheets

    Directory of Open Access Journals (Sweden)

    Karthaus Jan

    2017-06-01

    Full Text Available The purpose of this paper is to study the variation of the magnetic properties of non-oriented electrical steel sheets with the fatigue state during cyclic mechanical loading. The obtained results are central to the design of variable drives such as traction drives in electric vehicles in which varying mechanical loads, e.g. in the rotor core (centrifugal forces, alter the magnetic properties. Specimens of non-oriented electrical steel are subject to a cyclically varying mechanical tensile stress with different stress amplitudes and number of cycles. The specimens are characterised magnetically at different fatigue states for different magnetic flux densities and magnetising frequencies. The measurements show a variation in magnetic properties depending on the number of cycles and stress magnitude which can be explained by changes in the material structure due to a beginning mechanical fatigue process. The studied effect is critical for the estimation of the impact of mechanical material fatigue on the operational behaviour of electrical machines. Particularly in electrical machines with a higher speed where the rotor is stressed by high centrifugal forces, material fatigue occurs and can lead to deterioration of the rotor’s stack lamination.

  16. Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Thibault, Denis, E-mail: thibault.denis@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Bocher, Philippe, E-mail: philippe.bocher@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Thomas, Marc, E-mail: marc.thomas@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Lanteigne, Jacques, E-mail: lanteigne.jacques@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Hovington, Pierre, E-mail: hovington.pierre@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Robichaud, Patrice, E-mail: patrice.robichaud@riotinto.com [Centre de recherche et de developpement Arvida (CRDA), 1955, boul. Mellon, Jonquiere, Quebec, G7S 4K8 (Canada)

    2011-08-15

    Highlights: {yields} Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. {yields} Low cycle fatigue tests showed that this transformation to martensite is gradual. {yields} XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

  17. Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

    International Nuclear Information System (INIS)

    Thibault, Denis; Bocher, Philippe; Thomas, Marc; Lanteigne, Jacques; Hovington, Pierre; Robichaud, Patrice

    2011-01-01

    Highlights: → Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. → Low cycle fatigue tests showed that this transformation to martensite is gradual. → XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

  18. Statistical analysis of fatigue strain-life data for carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Keisler, J.; Chopra, O.K.; Shack, W.J.

    1994-08-01

    The existing fatigue strain vs. life (S-N) data, foreign and domestic, for carbon and low-alloy steels used in the construction of nuclear power plant components have been compiled and categorized according to material, loading, and environmental conditions. A statistical model has been developed for estimating the effects of the various test conditions on fatigue life. The results of a rigorous statistical analysis have been used to estimate the probability of initiating a fatigue crack. Data in the literature were reviewed to evaluate the effects of size, geometry, and surface finish of a component on its fatigue life. The fatigue S-N curves for components have been determined by applying design margins for size, geometry, and surface finish to crack initiation curves estimated from the model. The significance of the effect of environment on the current Code design curve and on the proposed interim design curves for carbon and low-alloy steels presented in NUREG/CR-5999 is discussed

  19. Fatigue assessment for selected connections of structural steel bridge components using the finite elements method

    Science.gov (United States)

    Śledziewski, Krzysztof

    2018-01-01

    Material fatigue it is one of the most frequent causes of steel bridge failures, particularly the bridges already existing. Thus, the procedure of fatigue life assessment is one of the most relevant procedures in a comprehensive assessment of load-carrying capacity and service life of the structure. A reliable assessment of the fatigue life is predominantly decisive for estimation of the remaining service life. Hitherto, calculation methods of welded joints took into account only stresses occurring in cross sections of whole elements and did not take into account stress concentration occurring in the vicinity of the weld, caused by geometrical aspects of the detail. At present, use of the Finite Element Analysis, makes possible looking for more accurate approach to the fatigue design of steel structures. The method of geometrical stresses is just such approach which is based on definition of stresses which take into account geometry of the detail. The study presents fatigue assessment of a representative type of welded joint in welded bridge structures. The testing covered longitudinal attachments. The main analyses were carried out on the basis of FEM and the method of local stresses, so-called "hot-spot" stresses. The obtained values of stresses were compared with the values obtained in accordance with the method of nominal stress.

  20. A study of microstructure, quasi-static response, fatigue, deformation and fracture behavior of high strength alloy steels

    Science.gov (United States)

    Kannan, Manigandan

    The history of steel dates back to the 17th century and has been instrumental in the betterment of every aspect of our lives ever since, from the pin that holds the paper together to the Automobile that takes us to our destination steel touches everyone every day. Path breaking improvements in manufacturing techniques, access to advanced machinery and understanding of factors like heat treatment, corrosion resistance have aided in the advancement in the properties of steel in the last few years. In this dissertation document, the results of a study aimed at the influence of alloy chemistry, processing and influence of the quasi static and fatigue behavior of seven alloy steels is discussed. The microstructure of the as-received steel was examined and characterized for the nature and morphology of the grains and the presence of other intrinsic features in the microstructure. The tensile, cyclic fatigue and bending fatigue tests were done on a fully automated closed-loop servo-hydraulic test machine at room temperature. The failed samples of high strength steels were examined in a scanning electron microscope for understanding the fracture behavior, especially the nature of loading be it quasi static, cyclic fatigue or bending fatigue . The quasi static and cyclic fatigue fracture behavior of the steels examined coupled with various factors contributing to failure are briefly discussed in light of the conjoint and mutually interactive influences of intrinsic microstructural effects, nature of loading, and stress (load)-deformation-microstructural interactions.

  1. The influence of plasma nitriding on the fatigue behavior of austenitic stainless steel types AISI 316 and AISI 304

    International Nuclear Information System (INIS)

    Varavallo, Rogerio; Manfrinato, Marcos Dorigao; Rossino, Luciana Sgarbi; Spinelli, Dirceu; Riofano, Rosamel Melita Munoz

    2010-01-01

    The plasma nitriding process has been used as an efficient method to optimize the surface properties of steel and alloy in order to increase their wear, fatigue and corrosion resistance. This paper reports on a study of the composition and influence of the nitrided layer on the high-cycle fatigue properties of the AISI 316 and 304 type austenitic stainless steels. Test specimens of AISI 316 and 304 steel were nitrided at 400 deg C for 6 hours under a pressure of 4.5 mbar, using a gas mixture of 80% volume of H 2 and 20% volume of N 2 . The rotary fatigue limit of both nitrided and non-nitrided steels was determined, and the effect of the treatment on the fatigue limit of the two steels was evaluated. The mechanical properties of the materials were evaluated based on tensile tests, and the nitrided layer was characterized by microhardness tests, scanning electron microscopy and X-ray diffraction. The resulting nitride layer showed high hardness and mechanical strength, increasing the fatigue limit of the nitrided material in comparison with the non-nitrided one. The fatigue limit of the 316 steel increased from 400 MPa to 510 MPa in response to nitriding, while that of the 304 steel increased from 380 MPa to 560 MPa. One of the contributing factors of this increase was the introduction of residual compressive stresses during the surface hardening process, which reduce the onset of crack formation underneath the nitride layer. (author)

  2. Sensitivity of the magnetization curves of different austenitic stainless tube and pipe steels to mechanical fatigue

    International Nuclear Information System (INIS)

    Niffenegger, M.; Leber, H.J.

    2008-01-01

    In meta-stable austenitic stainless steels, fatigue is accompanied by a partial strain-induced transformation of paramagnetic austenite to ferromagnetic martensite [G.B. Olsen, M. Cohen, Kinetics of strain induced martensite nucleation, Metall. Trans. 6 (1975) 791-795]. The associated changes of magnetic properties as the eddy current impedance, magnetic permeability or the remanence field may serve as an indication for the degree of fatigue and therefore the remaining lifetime of a component, even though the exact causal relationship between martensite formation and fatigue is not fully understood. However, measuring these properties by magnetic methods may be limited by the low affinity for strain-induced martensite formation. Thus other methods have to be found which are able to detect very small changes of ferromagnetic contents. With this aim the influence of cyclic strain loading on the magnetization curves of the austenitic stainless tube and pipe steels TP 321, 347, 304L and 316L is analysed in the present paper. The measured characteristic magnetic properties, which are the saturation magnetization, residual magnetization, coercive field and the field dependent permeability (AC-magnetization), are sensitive to fatigue and the corresponding material changes (martensitic transformation). In particular, the AC-magnetization was found to be very sensitive to small changes of the amount of strain induced martensite and therefore also to the degree of fatigue. Hence we conclude that applying magnetic minor loops are promising for the non-destructive evaluation of fatigue in austenitic stainless steel, even if a very small amount of strain induced martensite is formed

  3. The Effect of Nitriding Treatment Variables on the Fatigue Limit of Alloy Steel (34crnimo6) Under High Cycle Fatigue

    International Nuclear Information System (INIS)

    Mohamed, J.; Al-Alkawi, H.; Salameh, M.

    2009-01-01

    The aim of this research is to improve the fatigue limit for alloy steel (34CrNiMo6) by salt bath nitriding process. This property is more effective to increase the fatigue life for parts which are used in continuous cyclic loading. All the fatigue tests were implemented before and after nitriding process under rotating bending. Constant and variable capacity stresses were applied before and after nitriding processes. The nitriding process were implemented in salt bath component at three different times (1, 2, 3) hr when temperature was constant at (555 degree centigrade). The depth of the nitride layer reached (0.24, 0.37, 0.5) mm. The nitriding process repeated of another specimens at the same times but the temperature was (600 degree centigrade), the layer depth reached (0.28, 0.41, 0.55) mm. The formation of a high nitrogen iron phases were detected with a layer of the hard chrome nitrides on the surface. The nitriding process is forming the barriers on the surface that resist the initiation and propagation of cracks, as well as generating the compressive residual stresses which delay the progress of fatigue crack. This research deduced that the nitriding processes increased the fatigue limit and this limit is proportional to the time of the nitriding process. When the time increased, the depth of nitride layer is increased, but decreased when the temperature increased to (600 degree centigrade) because of the formation of brittle phase,in spite of the increase in layer depth. (author)

  4. Fatigue testing of weldable high strength steels under simulated service conditions

    Science.gov (United States)

    Tantbirojn, Natee

    There have been concerns over the effect of Cathodic Protection (CP) on weldable high strength steels employed in Jack-up production platform. The guidance provided by the Department of Energy HSE on higher strength steels, based on previous work, was to avoid overprotection as this could cause hydrogen embrittlement. However, the tests conducted so far at UCL for the SE702 type high strength steels (yields strength around 690 MPa) have shown that the effect of over protection on high strength steels may not be as severe as previously thought. For this thesis, SE702 high strength steels have been investigated in more detail. Thick (85mm) parent and ground welded plates were tested under constant amplitude in air and seawater with CP. Tests were also conducted on Thick (40mm) T-butt welded plates under variable amplitude loading in air and seawater with two CP levels (-800mV and -1050mV). Different backing materials (ceramic and metallic) for the welding process of the T-butt plates were also investigated. The variable amplitude sequences employed were generated using the Jack-up Offshore Standard load History (JOSH). The fatigue results are presented as crack growth and S/N curves. They were compared to the conventional offshore steel (BS 4360 50D). The results suggested that the fatigue life of the high strength steels was comparable to the BS 4360 50D steels. The effect of increasing the CP was found to be detrimental to the fatigue life but the effect was not large. The effect of CP was less noticeable in T-butt welded plates. However, in general, the effect of overprotection is not as detrimental to the Jack-up steels as previously thought. The load histories generated by JOSH were found to have some unfavourable characteristics. The framework is based on Markov Chain method and pseudo-random number generator for selecting sea-states. A study was carried out on the sequence generated by JOSH. The generated sequences were analysed for their validity for fatigue

  5. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Yanhui Wang

    2016-11-01

    Full Text Available In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  6. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels.

    Science.gov (United States)

    Wang, Yanhui; Zhang, Fucheng; Yang, Zhinan; Lv, Bo; Zheng, Chunlei

    2016-11-25

    In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF) performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  7. Model-experiment dialog in low cycle fatigue of stainless steels

    International Nuclear Information System (INIS)

    Aubin, Veronique

    2008-01-01

    In this HDR report (accreditation to supervise research), the author first proposes a synthesis of her research activities in the study of the mechanical behaviour in low cycle fatigue (cyclic hardening, plasticity surfaces), of modelling of the fatigue mechanical behaviour (phenomenological modelling, modelling with scale change), of progressive deformation (experimental analysis, analysis and simulation of plasticity at the microstructure scale). The second part addresses other activities in the field of research (behaviour and damage characterization of an austenitic-ferritic stainless steel), publication and education supervising, teaching

  8. Resistance to corrosion fatigue fracture in heat resistant steels and their welded joints

    International Nuclear Information System (INIS)

    Timofeev, B.T.; Fedorova, V.A.; Zvezdin, Yu.I.; Vajner, L.A.; Filatov, V.M.

    1987-01-01

    Experimental data on cyclic crack resistance of heat-resistant steels and their welded joints employed for production of the reactor bodies are for the first time generalized and systematized. The formula is suggested accounting for surface and inner defects to calculate the fatigue crack growth in the process of operation. This formula for surface defects regards also the effect of the corrosion factor. Mechanisms of the reactor water effect on the fatigue crack growth rate are considered as well as a combined effect of radiation and corrosive medium on this characteristic

  9. Fatigue behaviors and damage mechanism of a Cr-Mn-N austenitic steel

    DEFF Research Database (Denmark)

    Lv, Z.; Cai, P.; Yu, Tianbo

    2017-01-01

    . It was found that multi-site crack nucleation took place on the surface of the steel during fatigue, and that the crack population (i.e., fatigue weak-links) was found to be a Weibull function of the applied stress. Usually only one or two of the initiated cracks could lead to the final failure of the samples....... Most of the cracks were initiated at the{111} primary slip bands, especially within coarse grains. The cracks were deflected at grain boundaries, which effectively resisted short crack growth and arrested most of the short cracks in the alloy. It can be anticipated that grain refinement could further...

  10. Low cycle fatigue characteristics of duplex stainless steel with degradation under pure torsional load

    International Nuclear Information System (INIS)

    Kwon, Jae Do; Park, Joong Cheul

    2002-01-01

    Monotonic torsional and pure torsional low cycle fatigue (LCF) test with artificial degradation were performed on duplex stainless steel (CF8M). CF8M is used in pipes and valves in nuclear reactor coolant system. It was aged at 430 degree C for 3600hrs. Through the monotonic and LCF test, it is found that mechanical properties (i.e., yield strength, strain hardening exponent, strength coefficient etc.) increase and fatigue life (N f ) decreases with degradation of material. The relationship between shear strain amplitude (γ α ) and N f was proposed

  11. Experimental evaluation of the fretting fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2013-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. A method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires along the length of the monostrand. The experimental data....... Moreover, the paper provides relevant information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of the monostrand undergoing flexural deformations. The results presented herein are of special interest for the fatigue analysis of modern stay...

  12. Ratcheting and low cycle fatigue behavior of SA333 steel and their life prediction

    International Nuclear Information System (INIS)

    Paul, Surajit Kumar; Sivaprasad, S.; Dhar, S.; Tarafder, S.

    2010-01-01

    Ratcheting and low cycle fatigue (LCF) experiments have been conducted at 25 o C temperature in laboratory environment under different loading conditions. SA333 steel exhibits cyclic hardening throughout its life during LCF. It is found that ratcheting strain increases with both increasing mean stress and stress amplitude. It has also been noticed that plastic strain amplitude and plastic strain energy decrease with increase in mean stress at constant stress amplitude. Ratcheting and LCF life in the range of 10 2 -10 5 cycles have been predicted with the help of a mean stress-based fatigue lifing equation.

  13. Critical cleavage fracture stress characterization of A508 nuclear pressure vessel steels

    International Nuclear Information System (INIS)

    Wu, Sujun; Jin, Huijin; Sun, Yanbin; Cao, Luowei

    2014-01-01

    The critical cleavage fracture stress of SA508 Gr.4N and SA508 Gr.3 low alloy reactor pressure vessel (RPV) steels was studied through the combination of experiments and finite element method (FEM) analysis. The results showed that the value of the local cleavage fracture stress, σ F , of SA508 Gr.4N steel was significantly higher than that of SA508 Gr.3 steel. Detailed microstructural analysis was carried out using FEGSEM which revealed much smaller grains, finer and more homogenous carbide particles formed in SA508 Gr.4N steel. Compared with the SA508 Gr.3 steel currently used in the nuclear industry, the SA508 Gr.4N steel possesses higher strength and notch toughness as well as improved cleavage fracture behavior, and is considered a better candidate RPV steel for the next generation nuclear reactors. - Highlights: • Critical cleavage fracture stress was calculated through experiments and FEM. • Effects of both grain and carbide particle sizes on σ F were discussed. • The SA508 Gr.4N steel is a better candidate for the next generation nuclear reactors

  14. Fatigue crack growth in ferritic steels as influence by elevated temperature and environment

    International Nuclear Information System (INIS)

    Nakamura, H.; Minakawa, K.; Murali, K.; Mc Evily, A.J.

    1987-01-01

    Fatigue crack growth studies have been carried out at room temperature and at 538 deg C in air as well as in vacuum in order to assess the influence of both temperature and environment on the growth process. The materials investigated were 2 1/4Cr-1Mo steel, a modified 9Cr-1Mo steel and a 9Cr-2Mo steel, as well as weldments of the 9Cr-2Mo steel. Crack opening levels were determined for all test conditions. The R-dependency of the crack growth rate could be accounted for by crack closure, both at room and elevated temperature. Closure in air at 538 deg C was due to oxidation, whereas at room temperature closure was due to microstructurally related roughness and the influence of oxygen. (Author)

  15. Detection of Fatigue Damage in a Steel Member

    DEFF Research Database (Denmark)

    Rytter, Anders; Brincker, Rune; Hansen, Lars Pilegaard

    1991-01-01

    In this paper the possibilities of detection of crack extension in a steel beam by observation of changes in the dynamical response are investigated. System changes are observed by frequency domain and the time domain techniques. The position and the size of the crack are found by finite element...

  16. Detection of Fatigue Damage in a Steel Member

    DEFF Research Database (Denmark)

    Rytter, A.; Brincker, Rune; Hansen, Lars Pilegaard

    In this paper the posibilities of detection of crack extension in a steel beam by observation of changes in the dynamical response are investigated. System changes are observed by frequency domain and time domain techniques. The position and the size of the crack by finite element calculations...

  17. Influence of Deposition Conditions on Fatigue Properties of Martensitic Stainless Steel with Tin Film Coated by Arc Ion Plating Method

    Science.gov (United States)

    Fukui, Satoshi; Yonekura, Daisuke; Murakami, Ri-Ichi

    The surface properties like roughness etc. strongly influence the fatigue strength of high-tensile steel. To investigate the effect of surface condition and TiN coating on the fatigue strength of high-strength steel, four-point bending fatigue tests were carried out for martensitic stainless steel with TiN film coated using arc ion plating (AIP) method. This study, using samples that had been polished under several size of grind particle, examines the influence of pre-coating treatment on fatigue properties. A 2-µm-thick TiN film was deposited onto the substrate under three kinds of polishing condition. The difference of the hardness originated in the residual stress or thin deformation layer where the difference of the size of grinding particle of the surface polishing. And it leads the transformation of the interface of the substrate and the TiN film and improves fatigue limit.

  18. Irradiation effects in strain aged pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M; Myers, H P

    1962-02-15

    Tensile specimens, Charpy-V notch and subsize impact specimens of an aluminium killed carbon manganese steel, have been irradiated at 160 - 190 deg C in the reactor G1. The total neutron dose received was 2.4 x 10{sup 18} n/cm{sup 2} (> 1 MeV). Specimens were prepared from normalized plate and from strain aged material from the same plate. It was found that the changes in brittle ductile transition temperature due to neutron irradiation and those due to strain ageing must be considered additive.

  19. The influence of the martensitic transformation on the fatigue of an AISI type 316 metastable stainless steel

    International Nuclear Information System (INIS)

    Pacheco, D.J; Sousa e Silva, A.S. de; Monteiro, S.N.

    The influence of the martensitic transformation on the process of pulse tension fatigue of a AISI type 316 metastable stainless steel was studied at 25 0 and 196 0 c. The fatigue tests were performed on annealed and cold worked specimens in order to separate the effects of static transformation, dynamic transformation and work hardening. The fatigue limits obtained from the corresponding Wohler curves were compared for the different test conditions. The results showed that the fatigue is not affected by the dynamically induced martensite. On the other hand the static martensite, previously induced, appears to decrease the resistance to fatigue. The reasons for these effects are discussed. (Author) [pt

  20. Effect of weld metal properties on fatigue crack growth behaviour of gas tungsten arc welded AISI 409M grade ferritic stainless steel joints

    International Nuclear Information System (INIS)

    Shanmugam, K.; Lakshminarayanan, A.K.; Balasubramanian, V.

    2009-01-01

    The effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on fatigue crack growth behaviour of the gas tungsten arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single 'V' butt welded joints. Centre cracked tensile (CCT) specimens were prepared to evaluate fatigue crack growth behaviour. Servo hydraulic controlled fatigue testing machine was used to evaluate the fatigue crack growth behaviour of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength, hardness and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

  1. Fatigue fracture analysis in medium carbon structural steel and austenitic stainless steel by X-ray fractography

    International Nuclear Information System (INIS)

    Rao, N.N.; Azmi bin Rahmat

    1994-01-01

    Apart from the reidual stresses present in the bulk material, a growing fatigue crack may develop its own stress field ahead of the crack tip which in turn could influence the crack propagation behaviour. A fracture surface analysis through measurement of the residual stress of a failed component may provide some additional useful information to that obtained through conventional metallurgical and fracture mechanics investigations. This method of fracture surface analysis using x-ray diffraction technique is known as X -ray Fractography . Residual stress (ρ sub γ) and the full width at half maximum (FWHM) of the x-ray diffraction profile of any reflection are determined at different crack lengths on the fracture surface. These are then corelated to the fracture toughness parameters such as fracture toughness K sub I sub C, the maximum stress intensity factor K sub max and the stress intensity factor range δK. The present investigation aims at detailed x-ray analysis of the fatigue fractured surfaces of the compact tension specimens prepared from ferritic and austenitic stainless steels. The ferritic steel has been subjected to various heat treatments to obtain different microstructures and mechanical properties. The overall observations are analyzed through fatigue (cumulative) damage and material science concepts

  2. Electrode for welding steel for WWER-1000 reactor pressure vessel

    International Nuclear Information System (INIS)

    Lakatos, L.

    Of two types of electrodes, ie., with an alloyed core and with an unalloyed core, an electrode was chosen consisting of a basic coat and an unalloyed core. Fluctuations are shown of shear strength, tensile strenght and contraction with the welding mode and annealing temperature. It was found that pre-heating to 250 and 350 degC, respectively, was most suitable for welding a pressure vessel manufactured from material designated SKODA A3/II. Annealing aimed at removing stress was chosen at 650 to 700 degC. (H.S.)

  3. Fatigue management considering LWR coolant environments

    International Nuclear Information System (INIS)

    Park, Heung Bae; Jin, Tae eun

    2000-01-01

    Design fatigue curve for structural material in the ASME Boiler and Pressure Vessel Code do not explicitly address the effects of reactor coolant environments on fatigue life. Environmentally assisted cracking (EAC) of low-alloy steels in light water reactor (LWR) coolant environments has been a concern ever since the early 1970's. And, recent fatigue test data indicate a significant decrease in fatigue lives of carbon steels, low-alloy steels and austenitic stainless steels in LWR coolant environments. For these reasons, fatigue of major components has been identified as a technical issue remaining to be resolved for life management and license renewal of nuclear power plants. In the present paper, results of recent investigations by many organizations are reviewed to provide technical justification to support the development of utility approach regarding the management of fatigue considering LWR coolant environments for the purpose of life management and license renewal of nuclear power plants. (author)

  4. Ultimate Pressure Capacity of Prestressed Concrete Containment Vessels with Steel Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Hahm, Dae Gi; Choun, Young Sun; Choi, In Kil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-10-15

    The ultimate pressure capacity (UPC) of the prestressed concrete containment vessel (PCCV) is very important since the PCCV are final protection to prevent the massive leakage of a radioactive contaminant caused by the severe accident of nuclear power plants (NPPs). The tensile behavior of a concrete is an important factor which influence to the UPC of PCCVs. Hence, nowadays, it is interested that the application of the steel fiber to the PCCVs since that the concrete with steel fiber shows an improved performance in the tensile behavior compared to reinforced concrete (RC). In this study, we performed the UPC analysis of PCCVs with steel fibers corresponding to the different volume ratio of fibers to verify the effectiveness of steel fibers on PCCVs

  5. Apparent embrittlement saturation and radiation mechanisms of reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Pachur, D.

    1981-01-01

    The irradiation and annealing results of three different reactor pressure vessel steels are reported. Steel A, a basic material according to ASTM A-533 B having 0.15 percent vanadium; and Steel C contained 3.2 percent nickel. The steels were irradiated at 150, 300, and 400 degree C with neutron fluxes of 6 multiplied by 10 11 and 3 multiplied by 10 13 neutrons (n)/cm 2 /s. An apparent saturation-in-irradiation effect was found within certain neutron fluence ranges. During the annealing, various recovery processes occur in different temperature ranges. These are characterized by various activation energies. The individual processes were determined by the different time dependencies at various temperatures. Two causes for the apparent saturation were discovered from the behavior of the annealing curves

  6. FATIGUE BEHAVIOR OF HOT-ROLLED STEEL INTENDED FOR COLD FORMING

    Directory of Open Access Journals (Sweden)

    Gejza Rosenberg

    2011-07-01

    Full Text Available In the work, there are presented measured tension and fatigue properties of eight low-carbon steels moulded in form of 20 kg ingots that were processed by controlled regime of rolling /cooling and then exposed to simulated effect of two coiling temperatures. The experimental results presented in the work show, that steels with ferrite-martensite or ferrite-bainitic microstructure have in comparison to ferrite-pearlitic or ferrite-carbidic microstructure better strength-plastic properties, but worse resistance to cyclic loading.

  7. Preliminary tension effect on low-cycle fatigue of 40Kh13 steel in gaseous hydrogen

    International Nuclear Information System (INIS)

    Romaniv, A.N.

    1984-01-01

    Comparative bending tests of specimens deformed by tension at 65, 18 and 30% in hydrogen and vacuum were accomplished to reveal the effect of preliminary tension on low-cycle fatigue strength of 40Kh13 martensitic steel. It was found that small amounts of preliminary strains induced a considerable decrease in low-cycle durability in vacuum and hydrogen which was connected with developing defects arising at the early stages of plastic deformation. A rather high degree of preliminary tension promoted steel homogenization, hydrogen embrittlement decrease and service behaviour improvement

  8. Mechanical behavior of 9Cr-1Mo-1V steel due to creep fatigue deformation

    International Nuclear Information System (INIS)

    Kim, Sang Tae; Kim, Jae Kyoung; Lee, Hak Sun; Oh, Sang Hyun; Kwun, Sook In; Kim, Chung Seok

    2005-01-01

    Creep-fatigue tests with trapezoid load wave were performed on a 9Cr-1Mo-1V steel at high temperature(550 .deg. C). Trapezoid load wave is considering about hold time for creep effects. we could find out some information in the relationship between number of cycles to failure and hold time. The number of cycles to failure depended on hold time. The cyclic behavior of 9Cr-1Mo-1V steel was characterized by cyclic softening with increasing number of cycles in high temperature. Also we could observe some cavity in the specimens. The size of cavity was different from each hold time

  9. A fatigue initiation parameter for gas pipe steel submitted to hydrogen absorption

    Energy Technology Data Exchange (ETDEWEB)

    Capelle, J; Gilgert, J; Pluvinage, G [LaBPS - Ecole Nationale d' Ingenieurs de Metz et Universite Paul Verlaine Metz, Ile du Saulcy, 57045 Metz (France)

    2010-01-15

    Fatigue initiation resistance has been determined on API 5L X52 gas pipe steel. Tests have been performed on Roman Tile (RT) specimen and fatigue initiation was detected by acoustic emission. A comparison between specimens electrolytically charged with hydrogen and specimens without hydrogen absorption were made and it has been noted that fatigue initiation time is reduced of about 3 times when hydrogen embrittlement occurs. It has been proposed to use the concept of Notch Stress Intensity Factor as parameter to describe the fatigue initiation process. Due to the fact that hydrogen is localised in area with high hydrostatic pressure, definitions of local effective stress and distance have been modified when hydrogen is absorbed. This modification can be explained by existence of a ductile-brittle transition with hydrogen concentration. The fatigue initiation resistance curve allows that to determine a threshold for large number of cycles of fatigue non initiation. This parameter introduced in a Failure Assessment Diagram (FAD) provides supplementary information about defect nocivity in gas pipes: a non-critical defect can be detected as dormant or not dormant defect i.e., as non propagating defect. (author)

  10. Low cycle fatigue behavior in a medium-carbon carbide-free bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Kang, J. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, F.C., E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Long, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, B. [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-06-01

    In the paper, different morphologies of bainite were obtained through isothermal quenching at 320 °C and 395 °C in a medium-carbon carbide-free bainitic steel. The cyclic deformation mechanism was explored by using low cycle fatigue testing. The volume fraction of retained austenite was measured by X-ray diffraction and the space partitioning of the solute atoms was constructed by three-dimensional atom probe. Results showed that the fatigue life at 320 °C was always higher than that at 395 °C under low and high total strain amplitude. The cyclic softening at the early fatigue stage increased the plastic strain of the sample which was responsible for the reduction of the fatigue life at 395 °C. Strain-induced retained austenite to martensite contributed to initial cyclic hardening, but almost having no effect on the subsequent cyclic stable/softening behaviors. The finer bainitic ferrite sheaves obtained at 320 °C changed the small fatigue crack propagation direction and delayed the crack propagation rate, which was beneficial for the fatigue properties. In addition, the substitutional atoms did not redistribute between the retained austenite and bainitic ferrite before and after cyclic deformation.

  11. Modelling probabilistic fatigue crack propagation rates for a mild structural steel

    Directory of Open Access Journals (Sweden)

    J.A.F.O. Correia

    2015-01-01

    Full Text Available A class of fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and local strain-life damage models have been proposed in literature. The fatigue crack growth is regarded as a process of continuous crack initializations over successive elementary material blocks, which may be governed by smooth strain-life damage data. Some approaches account for the residual stresses developing at the crack tip in the actual crack driving force assessment, allowing mean stresses and loading sequential effects to be modelled. An extension of the fatigue crack propagation model originally proposed by Noroozi et al. (2005 to derive probabilistic fatigue crack propagation data is proposed, in particular concerning the derivation of probabilistic da/dN-ΔK-R fields. The elastic-plastic stresses at the vicinity of the crack tip, computed using simplified formulae, are compared with the stresses computed using an elasticplastic finite element analyses for specimens considered in the experimental program proposed to derive the fatigue crack propagation data. Using probabilistic strain-life data available for the S355 structural mild steel, probabilistic crack propagation fields are generated, for several stress ratios, and compared with experimental fatigue crack propagation data. A satisfactory agreement between the predicted probabilistic fields and experimental data is observed.

  12. The frequency effect on the fatigue crack growth rate of 304 stainless steel

    International Nuclear Information System (INIS)

    Shih, Y.-S.; Chen, J.-J.

    1999-01-01

    Under cyclic loading condition, the fatigue crack growth (FCG) rate governed by stress intensity factor and stress ratio is well known; Walker's equation, Forman's equation and Elber's equation are typical formulae to describe the fatigue crack growth rate. However, the loading frequency effect on the fatigue crack growth rate has yet to be explored. Recently, studies have focused on the loading frequency effect on some visco-elastic materials, and have provided a clearer understanding of the frequency effect on the fatigue crack growth rate. In a physical sense, knowledge about the loading frequency effect on the fatigue crack growth rate for 304 stainless steel is still lacking. James conducted a lot of experiments, and through data analysis, he concluded an evaluation equation which is based upon the experimental illustration. In this study, the physical properties of the material are used to illustrate the modification of fatigue crack growth rate, and a new formula which is based upon the modified Forman's equation, is provided. (orig.)

  13. Study on low-cycle fatigue property of candidate stainless steels for SCWR

    International Nuclear Information System (INIS)

    Chen Le; Tang Rui; Liang Bo; Zhang Qiang; Liu Hong

    2013-01-01

    Low cyclic fatigue property of three austenitic stainless steels (316Ti, 347 and HR3C) as candidate materials for SCWR was investigated at room temperature (RT) and 650℃ under a strain amplitude of ± 0.5%, and fracture morphology of all the samples was observed by scanning electron microscope (SEM). The results showed that, at both temperatures the fatigue life of 347 was best and 316Ti worst. For each material, the area of hysteresis was nearly the same in the two temperatures. The elastic deformation was 0.1% - 0.15% both at RT and 650℃ for the three materials with different fatigue lives, indicating it had no direct connection with fatigue life. There was different cyclic hardening/saturation behavior for each material. The maximum/minimum stress of either HR3C or 347 was quite different at the two temperatures, while of 316Ti was almost the same. The cyclic hardening behavior was more remarkable in 316Ti compared with 347 at 650℃. SEM observation found that the fatigue striation width was only 1.87 μm for 347, but up to 4.67 μm and 3.0 μm for 316Ti and HR3C respectively, which further demonstrated that 347 had the best fatigue property at 650℃. (authors)

  14. Effect of helium on fatigue crack growth and life of reduced activation ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Nogami, Shuhei; Takahashi, Manabu; Hasegawa, Akira; Yamazaki, Masanori

    2013-01-01

    The effects of helium on the fatigue life, micro-crack growth behavior up to final fatigue failure, and fracture mode under fatigue in the reduced activation ferritic/martensitic steel, F82H IEA-heat, were investigated by low cycle fatigue tests at room temperature in air at a total strain range of 0.6–1.5%. Significant reduction of the fatigue life due to helium implantation was observed for a total strain range of 1.0–1.5%, which might be attributable to an increase in the micro-crack propagation rate. However, the reduction of fatigue life due to helium implantation was not significant for a total strain range of 0.6–0.8%. A brittle fracture surface (an original point of micro-crack initiation) and a cleavage fracture surface were observed in the helium-implanted region of fracture surface. A striation pattern was observed in the non-implanted region. These fracture modes of the helium-implanted specimen were independent of the strain range

  15. Fatigue crack growth behaviour of 21/4Cr1Mo steel tube at elevated temperature

    International Nuclear Information System (INIS)

    Bulloch, J.H.; Buchanan, L.W.

    1987-01-01

    The fatigue crack growth characteristics of 21/4Cr1Mo steel tube have been examined at 588 0 C over the frequency range 0.02-20 Hz and dwell time range 10-960 min. All tests were conducted under load control in laboratory air at an R-ratio of 0.5. The elevated temperature fatigue crack growth characteristics were adequately described in terms of the stress intensity range ΔKAPPA. The continuous cyclic test data exhibited a significant effect of frequency that agreed well with predicted effects using a simple mathematical model of the high temperature fatigue process. With the dwell time range of 10-100 min there was a significant dwell time effect on the critical ΔKAPPA level for creep-fatigue interactive growth. At dwell times > 100 min the dwell time effect saturates. When creep-fatigue interactive growth occurs, growth rates reside above the maximum for continuum-controlled fatigue crack growth, and exhibit a da/dN varies as ΔKAPPA 10 dependence; failure is then intergranular in nature. (author)

  16. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    Directory of Open Access Journals (Sweden)

    G. Magudeeswaran

    2014-03-01

    Full Text Available Quenched and Tempered (Q&T steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC in the heat affected zone (HAZ after welding. The use of austenitic stainless steel (ASS consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW and Flux cored arc welding (FCAW were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.

  17. S-N Fatigue and Fatigue Crack Propagation Behaviors of X80 Steel at Room and Low Temperatures

    Science.gov (United States)

    Jung, Dae-Ho; Kwon, Jae-Ki; Woo, Nam-Sub; Kim, Young-Ju; Goto, Masahiro; Kim, Sangshik

    2014-02-01

    In the present study, the S-N fatigue and the fatigue crack propagation (FCP) behaviors of American Petroleum Institute X80 steel were examined in the different locations of the base metal (BM), weld metal (WM), and heat-affected zone (HAZ) at 298 K, 223 K, and 193 K (25 °C, -50 °C, and -80 °C). The resistance to S-N fatigue of X80 BM specimen increased greatly with decreasing temperature from 298 K to 193 K (25 °C to -80 °C) and showed a strong dependency on the flow strength (½(yield strength + tensile strength)). The FCP rates of X80 BM specimen were substantially reduced with decreasing temperature from 298 K to 223 K (25 °C to -50 °C) over the entire ∆ K regime, while further reduction in FCP rates was not significant with temperature from 223 K to 193 K (-50 °C to -80 °C). The FCP rates of the X80 BM and the WM specimens were comparable with each other, while the HAZ specimen showed slightly better FCP resistance than the BM and the WM specimens over the entire ∆K regime at 298 K (25 °C). Despite the varying microstructural characteristics of each weld location, the residual stress appeared to be a controlling factor to determine the FCP behavior. The FCP behaviors of high strength X80 steel were discussed based on the microstructural and the fractographic observations.

  18. Influence of sodium on the low-cycle fatigue behavior of types 304 and 316 stainless steel

    International Nuclear Information System (INIS)

    Smith, D.L.; Zeman, G.J.; Natesan, K.; Kassner, T.F.

    1976-01-01

    Fatigue tests in sodium were conducted to investigate the influence of a high-temperature sodium environment on the low-cycle fatigue behavior of Types 304 and 316 stainless steel. The effects of testing in a sodium environment as well as long-term sodium exposure were investigated. The fatigue tests were conducted at 600 and 700 0 C in sodium of controlled purity, viz., approximately 1 ppM oxygen and 0.4 ppM carbon, at a strain rate of 4 x 10 -3 s -1 . The fatigue life of annealed Type 316 stainless steel is substantially greater in sodium than when tested in air; however, the fatigue life of annealed Type 304 stainless steel is altered much less when tested in sodium. A 1512-h preexposure to sodium had no significant effect on the fatigue life of Type 316 stainless steel tested in sodium. However, a similar exposure substantially increased the fatigue life of Type 304 stainless steel in sodium. 10 fig

  19. APFIM investigation of clustering in neutron-irradiated Fe-Cu alloys and pressure vessel steels

    International Nuclear Information System (INIS)

    Auger, P.; Pareige, P.; Blavette, D.

    1996-01-01

    Pressure vessel steels used in PWRs are known to be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are commonly supposed to result from the formation of point defects, dislocation loops, voids and copper-rich precipitates. However, the real nature of the irradiation induced damage, in these particularly low copper steels (>0,1 wt%), has not been clearly identify yet. A new experimental work has been carried out thanks to atom probe and field ion microscopy (APFIM) facilities and, more particularly with a new generation of atom probe recently developed, namely the tomographic atom probe (TAP), in order to improve: the understanding of the complex behavior of copper precipitation which occurs when low-alloyed Fe-Cu model alloys are irradiated with neutrons; the microstructural characterization of the pressure vessel steel of the CHOOZ A reactor under various fluences (French Surveillance Programme). The investigations clearly reveal the precipitation of copper-rich clusters in irradiated Fe-Cu alloys while more complicated Si, Ni, Mn and Cu-solute 'clouds' were observed to develop in the low-copper ferritic solid solution of the pressure vessel steel. (authors)

  20. Correlation between radiation damage and magnetic properties in reactor vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Kempf, R.A., E-mail: kempf@cnea.gov.ar [División Caracterización, GCCN, CAC-CNEA (Argentina); Sacanell, J. [Departamento Física de la Materia Condensada, GIyA, CAC-CNEA, CONICET (Argentina); Milano, J. [División Resonancias Magnéticas, CAB-CNEA, CONICET (Argentina); Guerra Méndez, N. [Departamento Física de la Materia Condensada, GIyA, CAC-CNEA, CONICET (Argentina); Winkler, E.; Butera, A. [División Resonancias Magnéticas, CAB-CNEA, CONICET (Argentina); Troiani, H. [División Física de Metales, CAB-CNEA and Instituto Balseiro (UNCU), CONICET (Argentina); Saleta, M.E. [División Resonancias Magnéticas, CAB-CNEA, CONICET (Argentina); Fortis, A.M. [Departamento Estructura y Comportamiento. Gerencia Materiales-GAEN, CAC-CNEA (Argentina)

    2014-02-01

    Since reactor pressure vessel steels are ferromagnetic, provide a convenient means to monitor changes in the mechanical properties of the material upon irradiation with high energy particles, by measuring their magnetic properties. Here, we discuss the correlation between mechanical and magnetic properties and microstructure, by studying the flux effect on the nuclear pressure vessel steel used in reactors currently under construction in Argentina. Charpy-V notched specimens of this steel were irradiated in the RA1 experimental reactor at 275 °C with two lead factors (LFs), 93 and 183. The magnetic properties were studied by means of DC magnetometry and ferromagnetic resonance. The results show that the coercive field and magnetic anisotropy spatial distribution are sensitive to the LF and can be explained by taking into account the evolution of the microstructure with this parameter. The saturation magnetization shows a dominant dependence on the accumulated damage. Consequently, the mentioned techniques are suitable to estimate the degradation of the reactor vessel steel.

  1. Fatigue crack propagation behavior and acoustic emission characteristics of the heat affected zone of super duplex stainless steel

    International Nuclear Information System (INIS)

    Do, Jae Yoon; Kim, Jin Hwan; Ahn, Seok Hwan; Park, In Duck; Kang, Chang Yong; Nam, Ki Woo

    2002-01-01

    Because duplex stainless steel shows the good strength and corrosion resistance properties, the necessity of duplex stainless steel, which has long life in severe environments, has been increased with industrial development. The fatigue crack propagation behavior of Heat Affected Zone(HAZ) has been investigated in super duplex stainless steel. The fatigue crack propagation rate of HAZ of super duplex stainless steel was faster than that of base metal of super duplex stainless steel. We also analysed acoustic emission signals during the fatigue test with time-frequency analysis method. According to the results of time-frequency analysis, the frequency ranges of 200-400 kHz were obtained by striation and the frequency range of 500 kHz was obtained due to dimple and separate of inclusion

  2. Fatigue testing of TBC on structural steel by cyclic bending

    Czech Academy of Sciences Publication Activity Database

    Mušálek, Radek; Kovářík, O.; Medřický, Jan; Curry, N.; Bjorklund, S.; Nylen, P.

    2015-01-01

    Roč. 24, 1-2 (2015), s. 168-174 ISSN 1059-9630 R&D Projects: GA ČR(CZ) GPP108/12/P552 Institutional support: RVO:61389021 Keywords : atmospheric plasma spray * failure mechanism * fatigue * NiCoCrAlY * thermal barrier coatings * yttria-stabilized zirconia Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.568, year: 2015 http://link.springer.com/article/10.1007%2Fs11666-014-0180-4

  3. Fatigue crack growth of 316NG austenitic stainless steel welds at 325 °C

    Science.gov (United States)

    Li, Y. F.; Xiao, J.; Chen, Y.; Zhou, J.; Qiu, S. Y.; Xu, Q.

    2018-02-01

    316NG austenitic stainless steel is a commonly-used material for primary coolant pipes of pressurized water reactor systems. These pipes are usually joined together by automated narrow gap welding process. In this study, welds were prepared by narrow gap welding on 316NG austenitic stainless steel pipes, and its microstructure of the welds was characterized. Then, fatigue crack growth tests were conducted at 325 °C. Precipitates enriched with Mn and Si were found in the fusion zone. The fatigue crack path was out of plane and secondary cracks initiated from the precipitate/matrix interface. A moderate acceleration of crack growth was also observed at 325°Cair and water (DO = ∼10 ppb) with f = 2 Hz.

  4. An engineering method for estimating notch-size effect in fatigue tests on steel

    Science.gov (United States)

    Kuhn, Paul; Hardrath, Herbert F

    1952-01-01

    Neuber's proposed method of calculating a practical factor of stress concentration for parts containing notches of arbitrary size depends on the knowledge of a "new material constant" which can be established only indirectly. In this paper, the new constant has been evaluated for a large variety of steels from fatigue tests reported in the literature, attention being confined to stresses near the endurance limit. Reasonably satisfactory results were obtained with the assumption that the constant depends only on the tensile strength of the steel. Even in cases where the notches were cracks of which only the depth was known, reasonably satisfactory agreement was found between calculated and experimental factors. It is also shown that the material constant can be used in an empirical formula to estimate the size effect on unnotched specimens tested in bending fatigue.

  5. Corrosion Fatigue Characteristics of 12Cr Alloy Steel in Na2SO4 Solution

    Science.gov (United States)

    Bae, D. H.; Cho, S. Y.

    In order to estimate reliability of 12Cr alloy steel using as the turbine blade material of the steam power plant, its corrosion fatigue characteristics in Na2SO4 solution considering its percentage and temperature that were determined from the polarization test results were investigated, and compared with the results in air. The corrosion characteristic of 12Cr alloy steel was remarkably susceptible in 12.7wt.% (IM) Na2SO4 solution, and its susceptibility increased with the solution temperature increase. The corrosion fatigue characteristics in 12.7wt.% Na2SO4 solution were similar to that of in air at 25°C. The crack growth rate was however increased with the temperature of solution increase. The reasons showing such results are due to the difference of the crack growth mechanism according to the electro-chemical activity of the corrosion factors.

  6. X-ray analysis on the fatigue fracture surface of stainless steels

    International Nuclear Information System (INIS)

    Yoshioka, Yasuo; Guimard, B.

    1986-01-01

    Several X-ray diffraction parameters were observed on the fatigue fracture surface and its vicinity of both of SUS420J1 martensitic and SUS304 austenitic stainless steels and we discussed the relation between the stress intensity factor and these parameters. Monotonic plastic zone depth determined by the measurement of residual stress distribution proportionals to the squre of the maximum stress intensity factor as well as the case of ferritic steel. However, it is very difficult to find the relation between the stress intensity factor and residual stress or half value breadth of X-ray diffraction profile in the fracture surface for both materials. On the other hand, the amount of martensite induced by the transformation during fatigue process in SUS304 is related to the maximum stress intensity factor in the fracture surface regardless the stress ratio R. (author)

  7. Assessment of environmentally assisted cracking in PWR pressure vessel steels

    International Nuclear Information System (INIS)

    Tice, D.R.

    1987-01-01

    1) Since environmentally assisted cracking (EAC) is a time dependent process, assessment should be based on time rather than cycle dependent parameters. Thus an a/sub e/ vs a/sub i/ (or strain rate) basis for assessment should be used in preference to da/dN vs ΔK. 2) The threshold strain rate or velocity for the onset of EAC is controlled by material and environmental factors (e.g. steel sulphur content and water chemistry), and possibly by mechanical loading factors such as R ratio and load interaction effects. Above the threshold, crack growth rates are usually unacceptably rapid. 3) Sample calculations show that predicted crack growth rates using a time based model can be below or above those calculated using ASME XI depending on the value of the EAC threshold velocity but that for normal PWR operating conditions rates are likely to be below those predicted by the ASME code

  8. Fatigue life evaluation of 42CrMo4 nitrided steel by local approach: Equivalent strain-life-time

    International Nuclear Information System (INIS)

    Terres, Mohamed Ali; Sidhom, Habib

    2012-01-01

    Highlights: → Ion nitriding treatment of 42CrMo4 steel improves their fatigue strength by 32% as compared with the untreated state. → This improvement is the result of the beneficial effects of the superficial work- hardening and of the stabilized compressive residual stress. → The notch region is found to be the fatigue crack nucleation site resulting from a stress concentration (Kt = 1.6). → The local equivalent strain-fatigue life method was found to be an interesting predictive fatigue life method for nitrided parts. -- Abstract: In this paper, the fatigue resistance of 42CrMo4 steel in his untreated and nitrided state was evaluated, using both experimental and numerical approaches. The experimental assessment was conducted using three points fatigue flexion tests on notched specimens at R = 0.1. Microstructure analysis, micro-Vickers hardness test, and scanning electron microscope observation were carried out for evaluating experiments. In results, the fatigue cracks of nitrided specimens were initiated at the surface. The fatigue life of nitrided specimens was prolonged compared to that of the untreated. The numerical method used in this study to predict the nucleation fatigue life was developed on the basis of a local approach, which took into account the applied stresses and stabilized residual stresses during the cyclic loading and the low cyclic fatigue characteristics. The propagation fatigue life was calculated using fracture mechanics concepts. It was found that the numerical results were well correlated with the experimental ones.

  9. Tensile properties of irradiated and fatigue exposed stainless steel DIN X 6 CrNi 1811 (similar to AISI type 304) plate and welded joints

    International Nuclear Information System (INIS)

    Vries, M.I. de; Schaaf, B. van der; Elen, J.D.

    1979-10-01

    Test specimens of plate metal and welded joints of stainless steel DIN 1.4948, which is similar to AISI type 304, have been irradiated at 723 K and 823 K up to fluences of 1.10 23 n.m -2 and 5.10 24 n.m -2 (E > 0.1 MeV). These are representative conditions for the SNR-300 reactor vessel and inner components after 16 years of operation. High-rate (depsilon/dt = 1 s -1 ) tensile tests were performed after fatigue exposure up to various fractions of fatigue life (D) ranging from 5% to 95% at the same temperatures as the nominal temperatures of the irradiation series

  10. Influence Voltage Pulse Electrical Discharge In The Water at the Endurance Fatigue Of Carbon Steel

    OpenAIRE

    I.A. Vakulenko; A.G. Lisnyak

    2016-01-01

    Effect of pulses of electrical discharge in the water at the magnitude of the limited endurance under cyclic loading thermally hardened carbon steel was investigated. Observed increase stamina during cyclic loading a corresponding increase in the number of accumulated dislocations on the fracture surface. Using the equation of Cofino-Manson has revealed a decrease of strain loading cycle after treatment discharges. For field-cycle fatigue as a result of processing the voltage pulses carbon st...

  11. Room temperature fatigue behaviour of a normalized steel SAE 4140 in torsion

    International Nuclear Information System (INIS)

    Klumpp, S.; Eifler, D.; Macherauch, E.

    1990-01-01

    Cyclic deformation behaviour of a normalized steel SAE 4140 in shear strain-controlled torsion is characterized by cyclic softening and cyclic hardening. If mean shear stresses are superimposed to an alternating shear stress, cycle-dependent creep occurs, and the number of cycles to failure decreases. In shear strain-controlled torsional loading, mean stresses are observed to relax nearly to zero within a few cycles. Fatigue life is not influenced by mean shear strains. (orig.) [de

  12. Fatigue damage evaluation of stainless steel pipes in nuclear power plants using positron annihilation lineshape analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Yasuhiro [Institute of Nuclear Safety System, Inc., Mihama, Fukui (Japan); Nakamura, Noriko; Yusa, Satoru [Ishikawajima-Harima Heavy Industries Co., Tokyo (Japan)

    2002-09-01

    Since positron annihilation lineshape analysis can evaluate the degree of fatigue damage by detecting defects such as dislocations in metals, we applied this method to evaluate that in a type 316 stainless steel pipe which was used in the primary system of a nuclear power plant. Using {sup 68}Ge as a positron source, an energy spread of annihilation gamma ray peak from the material was measured and expressed as the S-parameter. Actual plant material cut from a surge line pipe of a pressurizer in a pressurized water reactor type nuclear power plant was measured by positron annihilation lineshape analysis and the S-parameter was obtained. Comparing the S-parameter with a relationship between the S-parameter and fatigue life ratio of the type 316 stainless steel, we evaluated the degree of fatigue damage of the actual material. Furthermore, to verify the evaluation, microstructures of the actual material were investigated with TEM (transmission electron microscope) to observe dislocation densities. As a result, a change in the S-parameter of the actual material from standard as-received material (type 316 stainless steel) was in the range from -0.0013 to 0.0014, while variations in the S-parameter of the standard as-received material were about {+-}0.002, and hence the differences between the actual material and the as-received material were negligible. Moreover, the dislocation density of the actual plant material observed with TEM was almost the same as that of the as-received one. In conclusion, we could confirm the applicability of the positron annihilation lineshape analysis to fatigue damage evaluation of stainless steel. (author)

  13. Influenced prior loading on the creep fatigue damage accumulation of heat resistant steels

    International Nuclear Information System (INIS)

    Kloos, K.H.; Granacher, J.; Scholz, A.

    1990-01-01

    On two heat resistant power plant steels the influence of prior strain cycling on the creep rupture behaviour and the influence of prior creep loading on the strain cycling behaviour is investigated. These influences concern the number of cycles to failure and the rupture time being the reference values of the generalized damage accumulation rule and they are used for a creep fatigue analysis of the results of long term service-type strain cycling tests. (orig.) [de

  14. Fatigue behavior of type 316 stainless steel following neutron irradiation inducing helium

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Liu, K.C.

    1980-01-01

    Since a tokamak fusion reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially the first wall and blanket. Type 316 stainless steel in the 20% cold-worked condition has been irradiated in the HFIR in order to introduce helium as well as displacement damage. A miniature hourglass specimen was developed for the reactor irradiations and subsequent fully reversed low cycle fatigue testing. For material irradiated and tested at 430 0 C in vacuum to a damage level of 7 to 15 dpa and containing 200 to 1000 appm He, a reduction in life by a factor of 3 to 10 was observed. An attempt was made to predict irradiated fatigue life by fitting data from irradiated material to a power law equation similar to the universal slopes equation and using ductility ratios from tensile tests to modify the equation for irradiated material

  15. 77 K Fatigue Crack Growth Rate of Modified CF8M Stainless Steel Castings

    International Nuclear Information System (INIS)

    Walsh, R. P.; Toplosky, V. J.; Han, K.; Heitzenroeder, P. J.; Nelson, B. E.

    2006-01-01

    The National Compact Stellerator Experiment (NCSX) is the first of a new class of stellarators. The modular superconducting coils in the NCSX have complex geometry that are manufactured on cast stainless steel (modified CF8M) winding forms. Although CF8M castings have been used before at cryogenic temperature there is limited data available for their mechanical properties at low temperatures. The fatigue life behavior of the cast material is vital thus a test program to generate data on representative material has been conducted. Fatigue test specimens have been obtained from key locations within prototype winding forms to determine the 77 K fatigue crack growth rate. The testing has successfully developed a representative database that ensures confident design. The measured crack growth rates are analyzed in terms of the Paris law parameters and the crack growth properties are related to the materials microstructure

  16. Dislocation concepts applied to fatigue properties of austenitic stainless steels including time-dependent modes

    Energy Technology Data Exchange (ETDEWEB)

    Tavassoli, A.A.

    1986-10-01

    Dislocation substructures formed in austenitic stainless steel 304L and 316L, fatigued at 673 K, 823 K and 873 K under total imposed strain ranges of 0.7 to 2.25%, and their correlation with mechanical properties have been investigated. In addition substructures formed at lower strain ranges have been examined using foils prepared from parts of the specimens with larger cross-sections. Investigation has also been extended to include the effect of intermittent hold-times up to 1.8 x 10/sup 4/s and sequential creep-fatigue and fatigue-creep. The experimental results obtained are analysed and their implications for current dislocation concepts and mechanical properties are discussed.

  17. Influence of De-icers on the Corrosion and Fatigue Behavior of 4140 Steel

    Science.gov (United States)

    Dean, William P.; Sanford, Brittain J.; Wright, Matthew R.; Evans, Jeffrey L.

    2012-11-01

    The purpose of this test was to evaluate the effects of calcium magnesium acetate (CMA) and sodium chloride (NaCl)—two common substances used to de-ice roadways—on the corrosion and fatigue behavior of annealed AISI 4140 steel. When CMA-corroded, NaCl-corroded, and as-machined samples were tested using R = 0.1, and f = 20 Hz, it was found that, within the scope of this study, samples corroded in both 3.5% CMA solution and 3.5% NaCl solution exhibited a lower fatigue strength than samples tested in the as-machined, uncorroded condition. For the short lives tested in this study, the difference in the effects of CMA and NaCl is minimal. However, at longer lives it is suspected, based on the trends, that the CMA solution would be less detrimental to the fatigue life.

  18. Estimation of Low Cycle Fatigue Response of 316 LN Stainless Steel in the Presence of Notch

    Science.gov (United States)

    Agrawal, Richa; Veerababu, J.; Goyal, Sunil; Sandhya, R.; Uddanwadiker, Rashmi; Padole, Pramod

    2018-02-01

    Notches introduced in the plain specimen result in the multiaxial state of stress that exists in the actual components due to the presence of flaws and defects. In the present work, low cycle fatigue life estimation of plain and notched specimens of 316 LN stainless steel is carried out at room temperature and 823 K. The plain and notched specimens with different notch radii were subjected to varying strain amplitudes ranging from ± 0.25 to ± 1.0% at a strain rate of 3 × 10-3 s-1. The fatigue life decreased in the presence of notch for all strain amplitudes at both the temperatures. The decrease in fatigue life was found to be more at room temperature than at 823 K. The fatigue life of the notched specimen decreased by approximately 94.2% compared to plain specimen at room temperature. However, at 823 K the decrease in fatigue life for notched specimen was approximately 84.6%. Low cycle fatigue life of the plain and notched specimens was estimated by Neuber's rule and finite element analysis approach. Neuber's rule overestimated the fatigue life by maximum factor of 2.6 for specimens at room temperature and by maximum factor of 5 for specimens at 823 K. However, it gives closer approximation at higher strain amplitudes at 823 K. Life estimation by finite element analysis at room temperature was within a factor of 1.5 as compared to experimental life, whereas it underestimated the fatigue life within a factor of 6 at high temperature.

  19. Mechanical Properties, Short Time Creep, and Fatigue of an Austenitic Steel

    Directory of Open Access Journals (Sweden)

    Josip Brnic

    2016-04-01

    Full Text Available The correct choice of a material in the process of structural design is the most important task. This study deals with determining and analyzing the mechanical properties of the material, and the material resistance to short-time creep and fatigue. The material under consideration in this investigation is austenitic stainless steel X6CrNiTi18-10. The results presenting ultimate tensile strength and 0.2 offset yield strength at room and elevated temperatures are displayed in the form of engineering stress-strain diagrams. Besides, the creep behavior of the steel is presented in the form of creep curves. The material is consequently considered to be creep resistant at temperatures of 400 °C and 500 °C when subjected to a stress which is less than 0.9 of the yield strength at the mentioned temperatures. Even when the applied stress at a temperature of 600 °C is less than 0.5 of the yield strength, the steel may be considered as resistant to creep. Cyclic tensile fatigue tests were carried out at stress ratio R = 0.25 using a servo-pulser machine and the results were recorded. The analysis shows that the stress level of 434.33 MPa can be adopted as a fatigue limit. The impact energy was also determined and the fracture toughness assessed.

  20. Mechanical Properties, Short Time Creep, and Fatigue of an Austenitic Steel.

    Science.gov (United States)

    Brnic, Josip; Turkalj, Goran; Canadija, Marko; Lanc, Domagoj; Krscanski, Sanjin; Brcic, Marino; Li, Qiang; Niu, Jitai

    2016-04-20

    The correct choice of a material in the process of structural design is the most important task. This study deals with determining and analyzing the mechanical properties of the material, and the material resistance to short-time creep and fatigue. The material under consideration in this investigation is austenitic stainless steel X6CrNiTi18-10. The results presenting ultimate tensile strength and 0.2 offset yield strength at room and elevated temperatures are displayed in the form of engineering stress-strain diagrams. Besides, the creep behavior of the steel is presented in the form of creep curves. The material is consequently considered to be creep resistant at temperatures of 400 °C and 500 °C when subjected to a stress which is less than 0.9 of the yield strength at the mentioned temperatures. Even when the applied stress at a temperature of 600 °C is less than 0.5 of the yield strength, the steel may be considered as resistant to creep. Cyclic tensile fatigue tests were carried out at stress ratio R = 0.25 using a servo-pulser machine and the results were recorded. The analysis shows that the stress level of 434.33 MPa can be adopted as a fatigue limit. The impact energy was also determined and the fracture toughness assessed.

  1. A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique

    International Nuclear Information System (INIS)

    Oh, Sae Wook; Park, Young Chul; Park, Soo Young; Kim, Deug Jin; Hue, Sun Chul

    1996-01-01

    This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, W y , were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. K max could be estimated by the measurement of W y

  2. Fatigue life response of ASME SA 106-B steel in pressurized water reactor environments

    Energy Technology Data Exchange (ETDEWEB)

    Terrell, J B [Materials Engineering Associates, Inc., Lanham, MD (USA)

    1989-01-01

    Fatigue strain-life tests were conducted on ASMESA 106-B piping steel base metal and weld metal specimens in 288{sup 0}C (550{sup 0}F) pressurized water reactor (PWR) environments as a function of strain amplitude, strain ratio, notch acuity, and cyclic frequency. Notched base metal specimens tested at 0.017 Hz in 0.001 part per million (ppm) dissolved oxygen environments nearly completely used up the margins of safety of 2 on stress and 20 on cycles incorporated into the ASMA Section III design curve for carbon steels. Tests conducted with smooth base metal and weld metal specimens at 1.0 Hz showed virtually no degradation in cycles to failure when compared to 288{sup 0}C air test results. In all cases, however, the effect of temperature alone reduced the margin of safety offered by the design curve in the low cycle regime for the test specimens. Comparison between the fatigue life results of smooth and notched specimens suggests that fatigue crack initiation is not significantly affected by 0.001 ppm dissolved oxygen, and that most of the observed degradation may be attributed to crack growth acceleration. These results suggest that the ASMA Section III methodology should be reviewed, taking into account the PWR environment variables which degrade the fatigue life of pressure-retaining components. (author).

  3. Effects of Coatings on the High-Cycle Fatigue Life of Threaded Steel Samples

    Science.gov (United States)

    Eder, M. A.; Haselbach, P. U.; Mishin, O. V.

    2018-05-01

    In this work, high-cycle fatigue is studied for threaded cylindrical high-strength steel samples coated using three different industrial processes: black oxidation, normal-temperature galvanization and high-temperature galvanization. The fatigue performance in air is compared with that of uncoated samples. Microstructural characterization revealed the abundant presence of small cracks in the zinc coating partially penetrating into the steel. This is consistent with the observation of multiple crack initiation sites along the thread in the galvanized samples, which led to crescent type fracture surfaces governed by circumferential growth. In contrast, the black oxidized and uncoated samples exhibited a semicircular segment type fracture surface governed by single-sided growth with a significantly longer fatigue life. Numerical fatigue life prediction based on an extended Paris-law formulation has been conducted on two different fracture cases: 2D axisymmetric multisided crack growth and 3D single-sided crack growth. The results of this upper-bound and lower-bound approach are in good agreement with experimental data and can potentially be used to predict the lifetime of bolted components.

  4. Low-cyclic fatigue behavior of modified 9Cr–1Mo steel at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Guguloth, Krishna; Sivaprasad, S. [CSIR-National Metallurgical laboratory, Material Science and Technology Division, Jamshedpur 831007 (India); Chakrabarti, D. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302 (India); Tarafder, S. [CSIR-National Metallurgical laboratory, Material Science and Technology Division, Jamshedpur 831007 (India)

    2014-05-01

    The low-cycle fatigue behavior of indigenously developed modified 9Cr–1Mo steel has been evaluated using a constant strain rate (1×10{sup −3} s{sup −1}) at ambient temperature (25 °C) and at elevated temperatures (500–600 °C) over the strain amplitudes varying between ±0.7% and ±1.2%. Cyclic stress response showed a gradual softening regime that ended in a stress plateau until complete failure of the specimens. The estimated fatigue life decreased with the increase in test temperature. The effect of temperature on fatigue life was more pronounced at lower strain amplitudes. The cyclic deformation behavior at different temperatures has been analyzed from hysteresis loop and also in view of the changes taking place in dislocation structure and dislocation–precipitation interaction. Evaluation of low-cycle fatigue properties of modified 9Cr–1Mo steel over a range of test temperature can help in designing components for in-core applications in fast breeder reactors and in super heaters for nuclear power plants.

  5. Fatigue life response of ASME SA 106-B steel in pressurized water reactor environments

    International Nuclear Information System (INIS)

    Terrell, J.B.

    1989-01-01

    Fatigue strain-life tests were conducted on ASMESA 106-B piping steel base metal and weld metal specimens in 288 0 C (550 0 F) pressurized water reactor (PWR) environments as a function of strain amplitude, strain ratio, notch acuity, and cyclic frequency. Notched base metal specimens tested at 0.017 Hz in 0.001 part per million (ppm) dissolved oxygen environments nearly completely used up the margins of safety of 2 on stress and 20 on cycles incorporated into the ASMA Section III design curve for carbon steels. Tests conducted with smooth base metal and weld metal specimens at 1.0 Hz showed virtually no degradation in cycles to failure when compared to 288 0 C air test results. In all cases, however, the effect of temperature alone reduced the margin of safety offered by the design curve in the low cycle regime for the test specimens. Comparison between the fatigue life results of smooth and notched specimens suggests that fatigue crack initiation is not significantly affected by 0.001 ppm dissolved oxygen, and that most of the observed degradation may be attributed to crack growth acceleration. These results suggest that the ASMA Section III methodology should be reviewed, taking into account the PWR environment variables which degrade the fatigue life of pressure-retaining components. (author)

  6. Effect of pre-deformation on the fatigue crack initiation life of X60 pipeline steel

    International Nuclear Information System (INIS)

    Zheng, M.; Luo, J.H.; Zhao, X.W.; Bai, Z.Q.; Wang, R.

    2005-01-01

    It is impossible to keep petroleum and natural gas transmission pipelines free from defects in the manufacturing, installation and servicing processes. The damage might endanger the safety of pipelines and even shorten their service life; gas or petroleum release due to defects may jeopardise the surrounding ecological environments with associated economic and life costs. Pre-tensile deformation of X60 steel is employed to experimentally simulate the influence of dents on the fatigue crack initiation life. The investigation indicates that the fatigue crack initiation life of pre-deformed X60 pipeline steel can be assessed by a previously proposed energetic approach. The threshold for crack initiation increases with the pre-deformation due to a strain hardening effect, while the fatigue resistant factor exhibits a maximum with pre-deformation owing to its special dependence on fracture strain and fracture strength. The result is expected to be beneficial to the understanding of the effect of damage on the safety of pipelines and fatigue life prediction

  7. Hydrogen Embrittlement Mechanism in Fatigue Behavior of Austenitic and Martensitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Sven Brück

    2018-05-01

    Full Text Available In the present study, the influence of hydrogen on the fatigue behavior of the high strength martensitic stainless steel X3CrNiMo13-4 and the metastable austenitic stainless steels X2Crni19-11 with various nickel contents was examined in the low and high cycle fatigue regime. The focus of the investigations were the changes in the mechanisms of short crack propagation. Experiments in laboratory air with uncharged and precharged specimen and uncharged specimen in pressurized hydrogen were carried out. The aim of the ongoing investigation was to determine and quantitatively describe the predominant processes of hydrogen embrittlement and their influence on the short fatigue crack morphology and crack growth rate. In addition, simulations were carried out on the short fatigue crack growth, in order to develop a detailed insight into the hydrogen embrittlement mechanisms relevant for cyclic loading conditions. It was found that a lower nickel content and a higher martensite content of the samples led to a higher susceptibility to hydrogen embrittlement. In addition, crack propagation and crack path could be simulated well with the simulation model.

  8. Effects of microstructure and residual stress on fatigue crack growth of stainless steel narrow gap welds

    International Nuclear Information System (INIS)

    Jang, Changheui; Cho, Pyung-Yeon; Kim, Minu; Oh, Seung-Jin; Yang, Jun-Seog

    2010-01-01

    The effects of weld microstructure and residual stress distribution on the fatigue crack growth rate of stainless steel narrow gap welds were investigated. Stainless steel pipes were joined by the automated narrow gap welding process typical to nuclear piping systems. The weld fusion zone showed cellular-dendritic structures with ferrite islands in an austenitic matrix. Residual stress analysis showed large tensile stress in the inner-weld region and compressive stress in the middle of the weld. Tensile properties and the fatigue crack growth rate were measured along and across the weld thickness direction. Tensile tests showed higher strength in the weld fusion zone and the heat affected zone compared to the base metal. Within the weld fusion zone, strength was greater in the inner weld than outer weld region. Fatigue crack growth rates were several times greater in the inner weld than the outer weld region. The spatial variation of the mechanical properties is discussed in view of weld microstructure, especially dendrite orientation, and in view of the residual stress variation within the weld fusion zone. It is thought that the higher crack growth rate in the inner-weld region could be related to the large tensile residual stress despite the tortuous fatigue crack growth path.

  9. Survey of postirradiation heat treatment as a means to mitigate radiation embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Hawthorne, J.R.

    1979-01-01

    Nuclear-radiation service typically produces a progressive reduction in the notch ductility of low-alloy steels. The reduction is manifested by a decrease in Charpy-V (Csub(v)) upper-shelf energy level and by an elevation in temperature of the ductile-to-brittle transition. Post irradiation heat treatment (annealing) is being investigated as a method for the reversal of these detrimental radiation effects for reactor-vessel steels. This study was undertaken to analyze factors which could affect annealing response, report data available to qualify suspected influences on annealing, and summarize experimental results generated for many commercially produced reactor materials and companion materials produced in the laboratory

  10. Hydrogen attack of pressure-vessel steel. Progress report, April 1, 1980-March 31, 1981

    International Nuclear Information System (INIS)

    Shewmon, P.G.

    1980-12-01

    The nucleation and growth of methane bubbles in the hydrogen attack of pressure vessel steel has been shown to obey models developed to describe the growth of bubbles limiting the creep ductility of metals. This has been done through studies of the effect of prior deformation on bubble nucleation as well as the effect of methane pressure (stress) and temperature on growth kinetics. A comprehensive model of the factors limiting growth has been developed. Its application to the hydrogen attack of a 2 1/4 Cr-1 Mo steel leads to several interesting predictions

  11. Electron-microscopic investigation of a pressure vessel steel after neutron irradiation

    International Nuclear Information System (INIS)

    Klaar, H.J.

    1975-01-01

    As an introduction, changes in the mechanical properties of pressure vessel steels on neutron irradiation and the causes of radiation embrittlement are discussed. After this, the author describes his own experiments with steel of the composition 0.19% C; 3.88% Ni; 1.57% Cr; 0.51% Mo; 0.2% V. Samples of this material were irradiated in-pile at 300 0 C with various neutron doses. To study the influence of neutron dose, irradiation temperature, and heat treatment on the mechanical properties, tensile tests, notched bar impact bending tests, hardness tests and structural analyses were carried out. The findings are reported. (GSC) [de

  12. Evaluation of defects induced by neutron radiation in reactor pressure vessels steels

    International Nuclear Information System (INIS)

    Lopez Jimenez, J.

    1978-01-01

    We have developed a method for calculating the production of neutron induced defects (depleted zone and crowdions) in ferritic pressure vessel steels for different neutron spectra. They have been analysed both the recoil primary atoms produced by elastic and inelastic collisions with fast neutrons and the ones produced by gamma-ray emission by thermal neutron absorption. Theoretical modelling of increasing in the ductile-brittle transition temperature of ferritic steels has been correlated with experimental data at irradiation temperature up to 400 degree centigree (Author) 15 refs

  13. Creep, fatigue and creep-fatigue damage evaluation and estimation of remaining life of SUS 304 austenitic stainless steel at high temperature

    International Nuclear Information System (INIS)

    Nishino, Seiichi; Sakane, Masao; Ohnami, Masateru

    1986-01-01

    Experimental study was made on the damage evaluation and estimation of remaining life of SUS 304 stainless steel in creep, low-cycle fatigue and creep-fatigue at 873 K in air. Creep, fatigue and creep-fatigue damage curves were drawn by the method proposed by D.A. Woodford and the relations between these damages and non-destructive parameters, i.e., microvickers hardness and quantities obtained from X-ray diffraction, were discussed. From these tests, the following conclusions were obtained. (1) Constant damage lines in the diagram of remaining lives in creep and fatigue could be drawn by changing load levels during the tests. Constant damage lines in creep-fatigue were also made by a linear damage rule using both static creep and fatigue damage curves, which agree well with the experimental data in creep-fatigue. (2) Microvickers hardness and half-value breadth in X-ray diffraction are appropriate parameters to evaluate creep damage but are not proper to evaluate fatigue damage. Particle size and microstrain obtained by X-ray profile analysis are good parameters to evaluate both creep and fatigue damages. (author)

  14. Behaviour of the nozzle corner region during the first phase of the fatigue test on scaled models of pressure vessels (JRC Vessel A)

    International Nuclear Information System (INIS)

    Jovanovic, A.; Lucia, A.C.; Brunnhuber, R.; Elbaz, J.M.; Schwarz, U.

    1987-01-01

    The work presented here deals mainly with the stress and fracture mechanics aspects of the first phase of the structural reliability experimental program based on the scaled experimental vessel at Ispra. The overall research and experiments make also part of the structural reliability assessment extrapolation pattern for the full-scale structures. The work presented here deals with the problem of the nozzle corner cracks induced by the fatigue under the pressure cycling

  15. Relationships between Charpy impact shelf energies and upper shelf Ksub(IC) values for reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Witt, F.J.

    1983-01-01

    Charpy shelf data and lower bound estimates of Ksub(IC) shelf data for the same steels and test temperatures are given. Included are some typical reactor pressure vessel steels as well as some less tough or degraded steels. The data were evaluated with shelf estimates of Ksub(IC) up to and exceeding 550 MPa√m. It is shown that the high shelf fracture toughness representative of tough reactor pressure vessel steels may be obtained from a knowledge of the Charpy shelf energies. The toughness transition may be obtained either by testing small fracture toughness specimens or by Charpy energy indexing. (U.K.)

  16. Updated embrittlement trend curve for reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Kirk, M.; Santos, C.; Eason, E.; Wright, J.; Odette, G.R.

    2003-01-01

    The reactor pressure vessels of commercial nuclear power plants are subject to embrittlement due to exposure to high energy neutrons from the core. Irradiation embrittlement of RPV belt-line materials is currently evaluated using US Regulatory Guide 1.99 Revision 2 (RG 1.99 Rev 2), which presents methods for estimating the Charpy transition temperature shift (ΔT30) at 30 ft-lb (41 J) and the drop in Charpy upper shelf energy (ΔUSE). A more recent embrittlement model, based on a broader database and more recent research results, is presented in NUREG/CR-6551. The objective of this paper is to describe the most recent update to the embrittlement model in NUREG/CR-6551, based upon additional data and increased understanding of embrittlement mechanisms. The updated ΔT30 and USE models include fluence, copper, nickel, phosphorous content, and product form; the ΔT30 model also includes coolant temperature, irradiation time (or flux), and a long-time term. The models were developed using multi-variable surface fitting techniques, understanding of the ΔT30 mechanisms, and engineering judgment. The updated ΔT30 model reduces scatter significantly relative to RG 1.99 Rev 2 on the currently available database for plates, forgings, and welds. This updated embrittlement trend curve will form the basis of revision 3 to Regulatory Guide 1.99. (author)

  17. Embrittlement recovery due to annealing of reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Eason, E.D.; Wright, J.E.; Nelson, E.E.; Odette, G.R.; Mader, E.V.

    1998-01-01

    The irradiation embrittlement of nuclear reactor pressure vessels (RPV) can be reduced by thermal annealing at temperatures higher than the normal operating conditions. The objective of this work was to analyze the pertinent data and develop quantitative models for estimating the recovery in 41 J (30 ft-lb) Charpy transition temperature (TT) and Charpy upper shelf energy (USE) due to annealing. An analysis data base was developed, reviewed for completeness and accuracy, and documented as part of this work. Models were developed based on a combination of statistical techniques, including pattern recognition and transformation analysis, and the current understanding of the mechanisms governing embrittlement and recovery. The quality of models fitted in this project was evaluated by considering both the Charpy annealing data used for fitting and a surrogate hardness data base. This work demonstrates that microhardness recovery is a good surrogate for shift recovery and that there is a high level of consistency between the observed annealing trends and fundamental models of embrittlement and recovery processes. (orig.)

  18. Regulatory aspects of radiation embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Randall, P.N.

    1979-01-01

    One purpose of this conference, is to re-examine the conventional wisdom about neutron radiation embrittlement and the methods used to counteract embrittlement in reactor vessels. Perhaps, there have been sufficient advances in fracture mechanics, core physics, dosimetry, and physical metallurgy to permit a forward step in the quantitative treatment of the subject. Certainly this would be consistent with the position of the U.S. Nuclear Regulatory Commission (the NRC) in general. ''There has been a continued evolution toward increased specificity.'' This statement appeared in the response prepared by the staff to a request from the Commission to explain how the staff decides to apply a new requirement and to whom, i.e., to back-fit or forward-fit-only or whatever. Pressure for increased specificity, i.e., for fleshing out general design criteria, comes from ''technical surprises'' in the form of operating experiences or from research information, and from attempts to improve our confidence in the safety of plants, especially new plants. Our goal is to have anticipated and evaluated all possible modes of failure with sufficient quantitativeness that the probability of failure can be estimated with some accuracy. Failing this, regulators demand large margins of safety to cover our ignorance

  19. Development of a Fatigue Model for Low Alloy Steels Using a Cycle-Dependent Cohesive Zone Law

    Directory of Open Access Journals (Sweden)

    Kyungmok Kim

    2014-03-01

    Full Text Available A fatigue model for SAE 4130 steels is developed using a cycle-dependent cohesive zone law. Reduction of fracture energy and degradation of stiffness are considered to describe failure resistance after certain number of cycles. The reduction rate of fracture energy is determined with experimental stress (S- number of cycles to failure (N scatter found in the literature. Three-dimensional finite element models containing a cohesive zone are generated with commercial software (ABAQUS. Calculated fatigue lives at different stress ratios are in good agreement with experimental ones. In addition, fatigue behavior of hardened SAE 4130 steels is predicted with that of normalized material.

  20. Influence of mechanical stress level in preliminary stress-corrosion testing on fatigue strength of a low-carbon steel

    International Nuclear Information System (INIS)

    Aleskerova, S.A.; Pakharyan, V.A.

    1978-01-01

    Effect of corrosion and mechanical factors of preliminary stress corrosion of a metal in its fatigue strength, has been investigated. Smooth cylindrical samples of 20 steel have been tested. Preliminary corrosion under stress has been carried out under natural sea conditions. It is shown that mechanical stresses in the case of preliminary corrosion affect fatigue strength of low-carbon steels, decreasing the range of limited durability and fatigue limit. This effect increases with the increase of stress level and agressivity of corrosive medium