wolfgang hoffelner | Swiss Federal Institute of Technology (ETH) (original) (raw)

Papers by wolfgang hoffelner

Journal of Materials Science, 2010

Future advanced nuclear plants are considered to operate as cogeneration plants for electricity a... more Future advanced nuclear plants are considered to operate as cogeneration plants for electricity and heat. Metals and alloys will be the main portion of structural materials employed (including fuel claddings). Due to the operating conditions these materials are exposed to damaging conditions like creep, fatigue, irradiation and its combinations. The paper uses the most important alloys: ferritic-martensitic steels, superalloys, oxide dispersion strengthened steels and to some extent titanium aluminides to discuss its responses to these exposure conditions. Extrapolation of stress rupture data, creep strain, swelling, irradiation creep and creep-fatigue interactions are considered. Although the stress rupture-and the creep behavior seem to meet expectations, the long design lives of 60 years are really challenging for extrapolations and particularly questions like negligible creep or occurrence of diffusion creep need special attention. Ferritic matrices (including oxide dispersion strengthened (ODS), steels) have better irradiation swelling behavior than austenites. Presence and size of dispersoids having a strong influence on high-temperature strength bring only insignificant improvements in irradiation creep. A strain-range-separation based approach for creep-fatigue interactions is presented which allows a real prediction of creep-fatigue lives. An assessment of capabilities and limitations of advanced materials modeling tools with respect to damage development is given.

... EC MINES PARIS,EVRY. HOURLIER, F. EC MINES PARIS,EVRY. PINEAU, A. EC MINES PARIS,EVRY. MC DOW... more ... EC MINES PARIS,EVRY. HOURLIER, F. EC MINES PARIS,EVRY. PINEAU, A. EC MINES PARIS,EVRY. MC DOWELL, DL. ... EC MINES PARIS,EVRY. COUDREUSE, L. EC NATL SUPER MINES ST ETIENNE. MAGNIN, T. EC NATL SUPER MINES ST ETIENNE. VINCENT, JN. ...

Elsevier eBooks, 2010

Abstract : New generation nuclear power plants (Generation IV) are designed to operate at higher ... more Abstract : New generation nuclear power plants (Generation IV) are designed to operate at higher temperatures, higher dose and in other environments compared with light water reactors. These demands require advanced materials which are able to operate safely, reliably, for a long time under such conditions. Nano-sized particles (oxide dispersion, carbo-nitrides) are promising candidates possessing superior strength and irradiation properties (particularly accommodation of He produced by irradiation). Properties of such materials (thermal creep, irradiation damage, irradiation creep) are summarized. Possibilities of how investigation methods for nano-structured materials (micro-sample testing, advanced analytical tools and materials modelling) could be used for determination of plant lifetimes are touched upon.

Springer eBooks, Oct 10, 2020

ABSTRACT

Nuclear Science, Mar 19, 2009

In the frame of the Generation IV initiative, different structural material candidates are invest... more In the frame of the Generation IV initiative, different structural material candidates are investigated at the Paul Scherrer Institute. These are oxide dispersion strengthened (ODS) steels, intermetallic materials and ceramic composite materials. The response of the material to different potential loads (irradiation, temperature …) is addressed in a multi-scale approach, both, modelling wise and also experimentally. The investigation of each scale delivers at least a qualitative understanding of possibly evolving damage in the material and also delivers a validation of the corresponding scale on the modelling side. From the experimental side, the lower end of the scale, the atomistic and structural level, can be investigated by conventional techniques, as for example transmission electron microscopy (TEM) and X-ray diffraction (XRD). However, the use of synchrotron radiation techniques offers an ideal, complementary way to investigate the material structure and other properties. This paper presents applications in the field of the ODS research, where the structural behaviour of the nanoscopic dispersoids can selectively be investigated, although only being present with roughly 5 wt % in the matrix. A study showing the structural behaviour of these oxide particles as a function of irradiation illustrates the potential of the extended X-ray absorption fine structure (EXAFS) technique. Using X-ray magnetic circular dichroism (XMCD), which is a difference-signal of two X-ray absorption spectra recorded for positive and negative helicities of the beam, the magnetic structure and some magnetic parameters, can be resolved. An example shows, how this can be applied to understand (Fe,Cr) systems, which is the base alloy of the investigated ODS steel. The results deliver an important crosscheck for modelling. Beside the presentation of these techniques, this paper shows how beamline techniques can serve nuclear research, with possibly activated materials. At the Paul Scherrer Institute, a sample holder for highly active materials has been developed, and has already served for EXAFS measurements at the Swiss Light Source (SLS). The set-up of this sample holder is briefly presented here.

International collaborations like the Generation IV initiative have the aim to create the technic... more International collaborations like the Generation IV initiative have the aim to create the technical basis for design and operation of advanced nuclear plants. Materials data shall be created in joint international materials projects. Data will be aggregated in databases like the “Generation IV materials handbook”. Mechanical data, but also microstructural information and information concerning materials production shall be included. This information will be used to create or amend code rules, to provide a basis for life-time analysis, damage assessments and for safety analyses. Such considerations need not only raw materials data but also tools for data analysis and evaluation. Multiscale modeling, establishing constitutive equations, development of advanced life-time prediction methods, quantitative correlation of mechanical properties with microstructure, quantification of environmental effects, tools for non destructive evaluation and condition based monitoring etc. are important analysis techniques needed for safe design and operation of advanced plants. These needs led the author to ask the question if current databases could not be enlarged by data evaluation and methods tools which could even end some day in the availability of web-based design codes and safety analyses. The database could also be used as a web-based discussion and development space. It could become then a powerful tool for knowledge management The paper will discuss this concept on basis of some examples.

Springer eBooks, Sep 22, 2012

ABSTRACT

A process for efficient and safe destruction of organics and vitrification of low/medium level ra... more A process for efficient and safe destruction of organics and vitrification of low/medium level radioactive waste is presented. A transferred arc plasma torch is employed as the heat source. The process handles several types of feed: combustibles, inorganic materials and metals. A non-leaching glassy solid which can be stored without further treatment is obtained as the final product. High volume-reduction factors can be achieved with this process. A wet gas cleaning system leads to extremely clean off-gas.

Springer eBooks, 1982

The fatigue crack growth properties of a number of industrial gas turbine alloys are reviewed ext... more The fatigue crack growth properties of a number of industrial gas turbine alloys are reviewed extensively in terms of fracture mechanics using data generated within the first two rounds of the European co-operation in science and technology (COST-action 50). The presentation considers the influence of microstructure, mean stress, environment and frequency on fatigue crack propagation rates in the low, medium and high ΔK regimes, based primarily on results gathered in the laboratories of the two authors. In practice, this type of data is used to assess the significance of defects in critical components and this aspect is discussed with reference to cast turbine blades and disc forgings.

Chemosphere, Oct 1, 1998

A systematic study with the aim to reduce NONO2, SO2 and to destroy VOCs and PCDD/F in flue gas b... more A systematic study with the aim to reduce NONO2, SO2 and to destroy VOCs and PCDD/F in flue gas by electrical discharge both in laboratory and at a pilot plant has been performed. Results show that 1) both indrect and direct treatment by electrical discharge can reduce NONO2 and SO2 and can destroy PCDD/F in flue gas; 2) Indirect treatment

Journal of Nuclear Materials, Jun 1, 2013

Irradia tion creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr hav... more Irradia tion creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr have been studied by homogeneously implantation with helium under uniaxial tensile stresses from 40 to 300 MPa. The maximum dose was about 1.2 dpa (5000 appm-He) with displac ement damage rates of 1 Â 10 À5 dpa/ s at a temperature of 300 °C. Irradiation creep compliances were measured to be 4.0 Â 10 À6 dpa À1 MPa À1 and 10 Â 10 À6 dpa À1 MPa À1 for 12 and 14Cr ODS, respectively. Subsequently, microstructural evolution was studied in detail by TEM observations, showing dislocation loops and bubbles distributed homogenously in the matrix. Some bubbles were attached to ODS particles. Finally, the effects of Cr content on irradiation creep and microstructural changes are discussed, including earlier results of a 19Cr ODS and a PM2000 ferritic steel.

Resources Conservation and Recycling, Apr 1, 1994

Environmental regulations and quality demands require clean and efficient processes for recovery ... more Environmental regulations and quality demands require clean and efficient processes for recovery of materials from scrap and waste. Thermal plasma is a heat source for recovering metals pyrometallurgicaly. High energy density, high temperatures and flexibility in the plasma gases employed are the basic advantages of plasma. Plasma methods are gaining importance for scrap melting of reactive and refractory metals and alloys, aluminum containing wastes, steel plant wastes and recovery of metals from spent catalysts. In the paper, some metal-containing wastes in different scrap and waste categories, related problems, goals and recycling furnace concepts will be presented and discussed: titanium scrap consolidation and refining (Plasma Cold Hearth Furnace), aluminum dross recycling (Plasma Rotating Hearth Furnace), MMC's, spent catalyst recycling and dust treatment. The paper also summarizes recent developments and some future aspects of plasma metal recovery from scrap and waste.

The separation of creep deformation and plastic deformation under slowly varying cyclic loading c... more The separation of creep deformation and plastic deformation under slowly varying cyclic loading conditions is discussed for the cast nickelbase-superalloy IN 738 LC at 850°C. Continuously changing loads were replaced by a stepwise increase or decrease of the load. Creep rates during cycling were compared with monotonic creep data and were found to be higher than monotonic creep rates. Under cyclic loading creep of the material was found even when the applied stress was zero. Such a behaviour can be understood in terms of an effective stress. The results are treated with respect to life time prediction methods.

OECD eBooks, Mar 19, 2009

Elsevier eBooks, 1984

ABSTRACT In order to correlate fatigue crack growth data measured at high strain amplitudes, the ... more ABSTRACT In order to correlate fatigue crack growth data measured at high strain amplitudes, the linear-elastic stress intensity factor has to be replaced by another load parameter. It is shown that a path independent integral Z, similar to the J-integral, is the appropriate parameter for materials for which the stress increments are a unique function of the strain increments. The Z parameter was used to interprete fatigue crack growth data measured on three steels over a wide range of strain amplitudes. Experimental evidence shows that the range where the present concept may be applied is limited but extends far beyond the range of the linear-elastic stress intensity factor.

A lab-size Plasma Arc Centrifugal Treatment (PACT) system has been operated with a variety of fee... more A lab-size Plasma Arc Centrifugal Treatment (PACT) system has been operated with a variety of feedstocks containing surrogates for radioactive wastes. The system uses energy from an arc, between a plasma torch and a rotating 0.6 m (2 ft.) diameter tub, inside a sealed chamber to melt inorganic components of waste fed and to evaporate organic and other volatile components. Burnable substances are oxidized either in the primary chamber or in a downstream secondary combustion chamber. The PACT-2 system can readily be moved to a new treatment site in tow 2.4 m x 2.4 m x 6 m (8` x 8` x 20`) shipping containers.

Recovery of metals from complex mixed wastes is a challenging task of modern material and waste m... more Recovery of metals from complex mixed wastes is a challenging task of modern material and waste management strategies. Thermal methods are an important tool in this respect. Plasma turned out to be particularly useful for treatment of complex or toxic wastes and residuals. In order to study plasma processes at reasonable costs, a pilot plasma plant has been used and wastes like spent Raney-Nickel catalysts, copper and aluminum drosses, and other metal containing wastes were investigated. The paper summarizes the most significant findings.

Elsevier eBooks, 2014

Abstract: Structural materials are key elements in the safe and reliable operation of machine and... more Abstract: Structural materials are key elements in the safe and reliable operation of machine and plant components. However, the harsh operating conditions found in power plants are at the limits of what current materials can withstand. Metallic materials remain widely used for structural applications, with the implementation of nanofeatures allowing their use in more extreme service conditions. The most significant improvement is in their creep and stress rupture properties, obtained through the inclusion of nanosized obstacles. These features act as sinks for helium, a by-product of radiation exposure in reactors. Nanosized grains may help to improve strength and radiation resistance, but their stability at elevated temperatures requires further enhancement. Nanosized powders are another option.

Springer eBooks, 1987

The applicability of crack growth laws for a quantitative evaluation of the low cycle fatigue (LC... more The applicability of crack growth laws for a quantitative evaluation of the low cycle fatigue (LCF) curves of smooth specimens tested at elevated temperatures is discussed. Crack growth laws (Δa/ΔN versus cyclic J) were integrated between an initial crack length and a final crack length. Typical high temperature materials: CrMoV-steels, a cast superalloy and an oxide dispersion alloy (ODS) were studied. I£F-curves of CrMoV steels can be well predicted. For the other materials and for creep-fatigue not so good predictions were obtained.

Journal of Materials Science, 2010

Future advanced nuclear plants are considered to operate as cogeneration plants for electricity a... more Future advanced nuclear plants are considered to operate as cogeneration plants for electricity and heat. Metals and alloys will be the main portion of structural materials employed (including fuel claddings). Due to the operating conditions these materials are exposed to damaging conditions like creep, fatigue, irradiation and its combinations. The paper uses the most important alloys: ferritic-martensitic steels, superalloys, oxide dispersion strengthened steels and to some extent titanium aluminides to discuss its responses to these exposure conditions. Extrapolation of stress rupture data, creep strain, swelling, irradiation creep and creep-fatigue interactions are considered. Although the stress rupture-and the creep behavior seem to meet expectations, the long design lives of 60 years are really challenging for extrapolations and particularly questions like negligible creep or occurrence of diffusion creep need special attention. Ferritic matrices (including oxide dispersion strengthened (ODS), steels) have better irradiation swelling behavior than austenites. Presence and size of dispersoids having a strong influence on high-temperature strength bring only insignificant improvements in irradiation creep. A strain-range-separation based approach for creep-fatigue interactions is presented which allows a real prediction of creep-fatigue lives. An assessment of capabilities and limitations of advanced materials modeling tools with respect to damage development is given.

... EC MINES PARIS,EVRY. HOURLIER, F. EC MINES PARIS,EVRY. PINEAU, A. EC MINES PARIS,EVRY. MC DOW... more ... EC MINES PARIS,EVRY. HOURLIER, F. EC MINES PARIS,EVRY. PINEAU, A. EC MINES PARIS,EVRY. MC DOWELL, DL. ... EC MINES PARIS,EVRY. COUDREUSE, L. EC NATL SUPER MINES ST ETIENNE. MAGNIN, T. EC NATL SUPER MINES ST ETIENNE. VINCENT, JN. ...

Elsevier eBooks, 2010

Abstract : New generation nuclear power plants (Generation IV) are designed to operate at higher ... more Abstract : New generation nuclear power plants (Generation IV) are designed to operate at higher temperatures, higher dose and in other environments compared with light water reactors. These demands require advanced materials which are able to operate safely, reliably, for a long time under such conditions. Nano-sized particles (oxide dispersion, carbo-nitrides) are promising candidates possessing superior strength and irradiation properties (particularly accommodation of He produced by irradiation). Properties of such materials (thermal creep, irradiation damage, irradiation creep) are summarized. Possibilities of how investigation methods for nano-structured materials (micro-sample testing, advanced analytical tools and materials modelling) could be used for determination of plant lifetimes are touched upon.

Springer eBooks, Oct 10, 2020

ABSTRACT

Nuclear Science, Mar 19, 2009

In the frame of the Generation IV initiative, different structural material candidates are invest... more In the frame of the Generation IV initiative, different structural material candidates are investigated at the Paul Scherrer Institute. These are oxide dispersion strengthened (ODS) steels, intermetallic materials and ceramic composite materials. The response of the material to different potential loads (irradiation, temperature …) is addressed in a multi-scale approach, both, modelling wise and also experimentally. The investigation of each scale delivers at least a qualitative understanding of possibly evolving damage in the material and also delivers a validation of the corresponding scale on the modelling side. From the experimental side, the lower end of the scale, the atomistic and structural level, can be investigated by conventional techniques, as for example transmission electron microscopy (TEM) and X-ray diffraction (XRD). However, the use of synchrotron radiation techniques offers an ideal, complementary way to investigate the material structure and other properties. This paper presents applications in the field of the ODS research, where the structural behaviour of the nanoscopic dispersoids can selectively be investigated, although only being present with roughly 5 wt % in the matrix. A study showing the structural behaviour of these oxide particles as a function of irradiation illustrates the potential of the extended X-ray absorption fine structure (EXAFS) technique. Using X-ray magnetic circular dichroism (XMCD), which is a difference-signal of two X-ray absorption spectra recorded for positive and negative helicities of the beam, the magnetic structure and some magnetic parameters, can be resolved. An example shows, how this can be applied to understand (Fe,Cr) systems, which is the base alloy of the investigated ODS steel. The results deliver an important crosscheck for modelling. Beside the presentation of these techniques, this paper shows how beamline techniques can serve nuclear research, with possibly activated materials. At the Paul Scherrer Institute, a sample holder for highly active materials has been developed, and has already served for EXAFS measurements at the Swiss Light Source (SLS). The set-up of this sample holder is briefly presented here.

International collaborations like the Generation IV initiative have the aim to create the technic... more International collaborations like the Generation IV initiative have the aim to create the technical basis for design and operation of advanced nuclear plants. Materials data shall be created in joint international materials projects. Data will be aggregated in databases like the “Generation IV materials handbook”. Mechanical data, but also microstructural information and information concerning materials production shall be included. This information will be used to create or amend code rules, to provide a basis for life-time analysis, damage assessments and for safety analyses. Such considerations need not only raw materials data but also tools for data analysis and evaluation. Multiscale modeling, establishing constitutive equations, development of advanced life-time prediction methods, quantitative correlation of mechanical properties with microstructure, quantification of environmental effects, tools for non destructive evaluation and condition based monitoring etc. are important analysis techniques needed for safe design and operation of advanced plants. These needs led the author to ask the question if current databases could not be enlarged by data evaluation and methods tools which could even end some day in the availability of web-based design codes and safety analyses. The database could also be used as a web-based discussion and development space. It could become then a powerful tool for knowledge management The paper will discuss this concept on basis of some examples.

Springer eBooks, Sep 22, 2012

ABSTRACT

A process for efficient and safe destruction of organics and vitrification of low/medium level ra... more A process for efficient and safe destruction of organics and vitrification of low/medium level radioactive waste is presented. A transferred arc plasma torch is employed as the heat source. The process handles several types of feed: combustibles, inorganic materials and metals. A non-leaching glassy solid which can be stored without further treatment is obtained as the final product. High volume-reduction factors can be achieved with this process. A wet gas cleaning system leads to extremely clean off-gas.

Springer eBooks, 1982

The fatigue crack growth properties of a number of industrial gas turbine alloys are reviewed ext... more The fatigue crack growth properties of a number of industrial gas turbine alloys are reviewed extensively in terms of fracture mechanics using data generated within the first two rounds of the European co-operation in science and technology (COST-action 50). The presentation considers the influence of microstructure, mean stress, environment and frequency on fatigue crack propagation rates in the low, medium and high ΔK regimes, based primarily on results gathered in the laboratories of the two authors. In practice, this type of data is used to assess the significance of defects in critical components and this aspect is discussed with reference to cast turbine blades and disc forgings.

Chemosphere, Oct 1, 1998

A systematic study with the aim to reduce NONO2, SO2 and to destroy VOCs and PCDD/F in flue gas b... more A systematic study with the aim to reduce NONO2, SO2 and to destroy VOCs and PCDD/F in flue gas by electrical discharge both in laboratory and at a pilot plant has been performed. Results show that 1) both indrect and direct treatment by electrical discharge can reduce NONO2 and SO2 and can destroy PCDD/F in flue gas; 2) Indirect treatment

Journal of Nuclear Materials, Jun 1, 2013

Irradia tion creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr hav... more Irradia tion creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr have been studied by homogeneously implantation with helium under uniaxial tensile stresses from 40 to 300 MPa. The maximum dose was about 1.2 dpa (5000 appm-He) with displac ement damage rates of 1 Â 10 À5 dpa/ s at a temperature of 300 °C. Irradiation creep compliances were measured to be 4.0 Â 10 À6 dpa À1 MPa À1 and 10 Â 10 À6 dpa À1 MPa À1 for 12 and 14Cr ODS, respectively. Subsequently, microstructural evolution was studied in detail by TEM observations, showing dislocation loops and bubbles distributed homogenously in the matrix. Some bubbles were attached to ODS particles. Finally, the effects of Cr content on irradiation creep and microstructural changes are discussed, including earlier results of a 19Cr ODS and a PM2000 ferritic steel.

Resources Conservation and Recycling, Apr 1, 1994

Environmental regulations and quality demands require clean and efficient processes for recovery ... more Environmental regulations and quality demands require clean and efficient processes for recovery of materials from scrap and waste. Thermal plasma is a heat source for recovering metals pyrometallurgicaly. High energy density, high temperatures and flexibility in the plasma gases employed are the basic advantages of plasma. Plasma methods are gaining importance for scrap melting of reactive and refractory metals and alloys, aluminum containing wastes, steel plant wastes and recovery of metals from spent catalysts. In the paper, some metal-containing wastes in different scrap and waste categories, related problems, goals and recycling furnace concepts will be presented and discussed: titanium scrap consolidation and refining (Plasma Cold Hearth Furnace), aluminum dross recycling (Plasma Rotating Hearth Furnace), MMC's, spent catalyst recycling and dust treatment. The paper also summarizes recent developments and some future aspects of plasma metal recovery from scrap and waste.

The separation of creep deformation and plastic deformation under slowly varying cyclic loading c... more The separation of creep deformation and plastic deformation under slowly varying cyclic loading conditions is discussed for the cast nickelbase-superalloy IN 738 LC at 850°C. Continuously changing loads were replaced by a stepwise increase or decrease of the load. Creep rates during cycling were compared with monotonic creep data and were found to be higher than monotonic creep rates. Under cyclic loading creep of the material was found even when the applied stress was zero. Such a behaviour can be understood in terms of an effective stress. The results are treated with respect to life time prediction methods.

OECD eBooks, Mar 19, 2009

Elsevier eBooks, 1984

ABSTRACT In order to correlate fatigue crack growth data measured at high strain amplitudes, the ... more ABSTRACT In order to correlate fatigue crack growth data measured at high strain amplitudes, the linear-elastic stress intensity factor has to be replaced by another load parameter. It is shown that a path independent integral Z, similar to the J-integral, is the appropriate parameter for materials for which the stress increments are a unique function of the strain increments. The Z parameter was used to interprete fatigue crack growth data measured on three steels over a wide range of strain amplitudes. Experimental evidence shows that the range where the present concept may be applied is limited but extends far beyond the range of the linear-elastic stress intensity factor.

A lab-size Plasma Arc Centrifugal Treatment (PACT) system has been operated with a variety of fee... more A lab-size Plasma Arc Centrifugal Treatment (PACT) system has been operated with a variety of feedstocks containing surrogates for radioactive wastes. The system uses energy from an arc, between a plasma torch and a rotating 0.6 m (2 ft.) diameter tub, inside a sealed chamber to melt inorganic components of waste fed and to evaporate organic and other volatile components. Burnable substances are oxidized either in the primary chamber or in a downstream secondary combustion chamber. The PACT-2 system can readily be moved to a new treatment site in tow 2.4 m x 2.4 m x 6 m (8` x 8` x 20`) shipping containers.

Recovery of metals from complex mixed wastes is a challenging task of modern material and waste m... more Recovery of metals from complex mixed wastes is a challenging task of modern material and waste management strategies. Thermal methods are an important tool in this respect. Plasma turned out to be particularly useful for treatment of complex or toxic wastes and residuals. In order to study plasma processes at reasonable costs, a pilot plasma plant has been used and wastes like spent Raney-Nickel catalysts, copper and aluminum drosses, and other metal containing wastes were investigated. The paper summarizes the most significant findings.

Elsevier eBooks, 2014

Abstract: Structural materials are key elements in the safe and reliable operation of machine and... more Abstract: Structural materials are key elements in the safe and reliable operation of machine and plant components. However, the harsh operating conditions found in power plants are at the limits of what current materials can withstand. Metallic materials remain widely used for structural applications, with the implementation of nanofeatures allowing their use in more extreme service conditions. The most significant improvement is in their creep and stress rupture properties, obtained through the inclusion of nanosized obstacles. These features act as sinks for helium, a by-product of radiation exposure in reactors. Nanosized grains may help to improve strength and radiation resistance, but their stability at elevated temperatures requires further enhancement. Nanosized powders are another option.

Springer eBooks, 1987

The applicability of crack growth laws for a quantitative evaluation of the low cycle fatigue (LC... more The applicability of crack growth laws for a quantitative evaluation of the low cycle fatigue (LCF) curves of smooth specimens tested at elevated temperatures is discussed. Crack growth laws (Δa/ΔN versus cyclic J) were integrated between an initial crack length and a final crack length. Typical high temperature materials: CrMoV-steels, a cast superalloy and an oxide dispersion alloy (ODS) were studied. I£F-curves of CrMoV steels can be well predicted. For the other materials and for creep-fatigue not so good predictions were obtained.