Strain/Oxidation Interactions in Steels and Model Alloys

Holmes, D.R.; Pascoe, R. T.

doi:10.1002/maco.19720231003

Cited by 29 publications

(11 citation statements)

References 36 publications

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“…This can be compared with a similar estimate of 1.2% for &-A1203 on Fe-18%-Cr-8%-Ni-A1 alloy ( 14). These values (in the range 1.4 to 2.3%) are considerably greater than the strains likely to be induced by differential thermal contraction between the alloy and oxide on cooling.…”

Section: Discussionmentioning

confidence: 61%

“…These apparently higher fracture strains for anodically formed oxides compared with those thermally formed oxides have been accounted for in terms of fewer inherent defects in the former oxides compared with the latter (14). These apparently higher fracture strains for anodically formed oxides compared with those thermally formed oxides have been accounted for in terms of fewer inherent defects in the former oxides compared with the latter (14).…”

Section: Discussionmentioning

confidence: 95%

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The tensile straining of oxidized Fe‐Cr‐Al‐Y alloys

Golightly

Stott

Wood

1979

Materials & Corrosion

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The apparent tensile fracture strains, at which cracking of @A12 O3 scales formed on Fe-Cr-Al-Y alloys during oxidation in 1 atm oxygen at 1200 "C occur, have been determined by two methods at room temperature. The values are reproducible and depend on the oxidation time but are within the range 1.4% to 2.3%. These are significantly higher than other published values for thermally formed oxides. It has also been observed that an intermediate thermal cycle to room temperature during the oxidation period does not affect significantly the subsequently measured fracture strain. These relatively high values are discussed in terms of two tentative hypotheses, one relating to flaws in the oxide, the other to possible loss of cohesion of oxide which is too fine to be detected by the methods used.

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Section: Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 95%

The tensile straining of oxidized Fe‐Cr‐Al‐Y alloys

Golightly

Stott

Wood

1979

Materials & Corrosion

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“…oxidized faster after straining. 7 If exposure temperatures are sufficiently high, there is no difference between oxidation rates of cold worked and annealed material because of concurrent annealing. 6 The present results (Fig.…”

Section: Oxidation Of Fracture Surfaces In High Strain Fatiguementioning

confidence: 99%

“…7 Enhanced 64 Metal Science February 1978 oxidation with deformation acting concurrently has been reported during high strain fatigue of A-286 alloy at 510°C, 8 and has been measured after high frequency fatigue of En2 steel in air at 500 and 570°C. 9 It is not surprising, therefore, that after high strain fatigue testing of low alloy steel specimens at 550°C in air, surfaces and cracks were wellendowed with oxide.!'…”

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confidence: 94%

Cyclic oxidation and crack growth during high strain fatigue of low alloy steel

Skelton¹,

Bucklow²

1978

Metal Science

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This paper attempts to assess the contribution of oxidation to crack growth during high strain fatigue of a Cr-Mo-V steel at 550°C from three separate oxidation studies. Stress-free data are clearly inapplicable to the highly strained crack tip and so it is first shown that internal stresses, as in bainitic material, promote enhanced oxidation. Weight gain experiments on oxide-free fracture surfaces are next described. It is shown that the stored energy of fatigue fracture likewise causes an increase in oxidation rate but that it is difficult to simulate the process at the tip of an advancing crack. Similarly, metallography of oxide in fatigue cracks does not reveal propagation. history. Finally, a dynamically worked surface, provided. by high-strain fatigue specimens deforming at 550°C, causes increasing oxidation with increasing total strain above a threshold value of oxide strain. It is shown that this is due to layering producing at least a tenfold increase compared with stress-free specimens. Therefore the cyclic surface growth data are used together with observed crack propagation rates in air and vacuum to estimate the oxidation rate in the highly-strained crack tip.Several effects contribute to the fatigue failure of low alloy steels at high temperature. As well as the fatigue strain cycle there may be a component of creep, and environmental attack also becomes more pronounced than at low temperatures. Therefore it is important to be able to separate the contributions of 'oxidation' and 'creep' damage in high temperature fatigue. For example, when creep occurred during stress relaxation in the tension cycle in fatigue of !Mo steel at 500°C, endurances were reduced.! This applied both for air and vacuum tests. Vacuum testing eliminates the gross oxidation component and, for !CrMo-V steel at 550°C, increases the endurance? Recent experiments on Cr-Mo-V steels at 550°C have also shown that cracks advance faster in air than in vacuum, both in high strain fatigue 3 and in tests at a given stress intensity.4The exceptions are at low stress or strain amplitudes in air, where the crack becomes'sealed with oxide.Oxide behaviour at grain boundaries is also known to influence fatigue-crack initiation and propagation. 5 Clearly, an oxide scale which is firmly adherent to the deforming underlying metal will improve fatigue life.Oxidation rates in iron are increased by surface cold work,6 and, in 2!Cr-IMo steel, by prestraining. 7 Enhanced 64 Metal Science February 1978 oxidation with deformation acting concurrently has been reported during high strain fatigue of A-286 alloy at 510°C,8 and has been measured after high frequency fatigue of En2 steel in air at 500 and 570°C. 9 It is not surprising, therefore, that after high strain fatigue testing of low alloy steel specimens at 550°C in air, surfaces and cracks were wellendowed with oxide.!' 3The purpose of the present work is to assess the contribution of such oxidation to fatigue crack growth, during high strain fatigue. It was realized that stress-free oxidation data...

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“…c lattice of 4 oxygen. Maximal symmetry-induced deformation is shown to be 5,8% and "effective" PBR value varies from 1.12 to 1.19 according to the type of the growth process defined by the phase diagram, although classical PBR value for the FeEeO system is 1.68 [8,26]. Calculated temperature-internal field phase diagram shows variety of growth regimes : isotropic growth without phase transition, second order phase transition without structural incompatibility of the substrate and the interface, first order phase transition resulting in the loss of elastic continuity and grain formation.…”

Section: Introductionmentioning

confidence: 99%

Symmetry-Induced Deformation and Reconstructive Phase Transformation in Metal-Oxide Interface : The Fe (001) example

et al. 1996

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A model is proposed for the structural transformation and corresponding induced deformation in physical three-dimensional interface of the metal-oxide system. The thermodynamical and elastic state of the system is described by the Landau-Ginzbourg fiee energy. Calculated theoretical phase diagram shows several different types of isothermal growth processes. The model is applied to the case of the oxidation of the (001) Fe surface.

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Strain/Oxidation Interactions in Steels and Model Alloys

Cited by 29 publications

References 36 publications

The tensile straining of oxidized Fe‐Cr‐Al‐Y alloys

The tensile straining of oxidized Fe‐Cr‐Al‐Y alloys

Cyclic oxidation and crack growth during high strain fatigue of low alloy steel

Symmetry-Induced Deformation and Reconstructive Phase Transformation in Metal-Oxide Interface : The Fe (001) example

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