Austenitic high interstitial steels vs. CoCrMo – Comparison of fatigue behavior

Gueler, Sedat; Schymura, Michael; Fischer, Alfons

doi:10.1016/j.ijfatigue.2015.02.015

Cited by 9 publications

(9 citation statements)

References 37 publications

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“…This could be related to the low stacking fault energy of 8 mJ/ m 2 . It has been shown earlier that below 15 mJ/m 2 also the stacking fault energy plays a distinct role for metals with planar sliding characteristics [18]. Still it must be mentioned that the transformation induced plasticity steel CrMnNiCN0.11 shows marked cyclic hardening while the transformation induced plasticity cobalt chromium molybdenum alloys which also possesses a stacking fault energy !…”

Section: Discussionmentioning

confidence: 95%

“…Still the cyclic behavior cannot be directly related in a simple manner to these criteria. Since these steels have more or less the same stacking fault energy it does not count as criterion in contrast to for example cobalt-chromium-molybdenum (CoCrMo) alloys, which gain a higher fatigue limit from a markedly smaller amount of interstitials because of their very small stacking fault energy [18]. For a given stacking fault energy this would leave carbon + nitrogen and carbon/nitrogen as possible alloying criteria governing the density of free electrons and, therefore, the ductility as well as any twinning-induced plasticity or transformation-induced plasticity mechanism.…”

Section: Introductionmentioning

confidence: 99%

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The influence of the nitrogen/nickel‐ratio on the cyclic behavior of austenitic high strength steels with twinning‐induced plasticity and transformation‐induced plasticity effects

Güler

Schymura

Fischer

et al. 2018

Materialwissenschaft Werkst

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Austenitic high nitrogen (AHNS) and austenitic high interstitial steels (AHIS) are of interest for mechanical engineering applications because of their unique combination of mechanical (strength, ductility), chemical (corrosion resistance) and physical (non-ferromagnetic) properties. But despite their high strength values e. g. after cold deformation up to 2 GPa in combination with an elongation to fracture of 30 %, which is based on twinning-induced plasticity (TWIP) mechanisms and transformation-induced plasticity (TRIP) mechanisms, the fatigue limit remains relatively small. While for chromium-nickel steels the fatigue limit rises with about 0.5-times the elastic limit it does not at all for austenitic high-nitrogen steels or only to a much smaller extent for nickel-free austenitic high-interstitial steels. The reasons are still not fully understood but this behavior can roughly be related to the tendency for planar or wavy slip. Now the latter is hindered by nitrogen and promoted by nickel. This contribution shows the fatigue behavior of chromium-manganese-carbon-nitrogen (CrMnCn) steels with carbon + nitrogen-contents up to 1.07 wt.%. Beside the governing influence of these interstitials on fatigue this study displays, how the nitrogen/nickel-ratio might be another important parameter for the fatigue behavior of such steels.Keywords: Austenitic high strength steels / Ramberg-Osgood / twinning-induced plasticity (TWIP) / transformation-induced plasticity (TRIP) / nitrogen-nickel ratio / cyclic behavior Schlü sselwö rter: Austenitische hochfeste Stä hle / Ramberg-Osgood / durch Zwillingsbildung induzierte Plastizitä t (TWIP) / umwandlungsbewirkte Plastizitä t (TRIP) / Stickstoff-Nickel Verhä ltnis / zyklische Belastung Corresponding author: S. Gü ler, Institut fü r die Technologien der Metalle, Lehrstuhl Werkstofftechnik, Universitä t Duisburg-Essen,

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

The influence of the nitrogen/nickel‐ratio on the cyclic behavior of austenitic high strength steels with twinning‐induced plasticity and transformation‐induced plasticity effects

Güler

Schymura

Fischer

et al. 2018

Materialwissenschaft Werkst

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“…Most fatigue papers concentrate on finite life tests as they show dislocation activities galore. But here, the infinite life is aimed for and, therefore, no distinct differences as to the microstructures before and after fatigue tests can be shown [13,35]. One additional aspect to be regarded comes from the fact that at the fatigue limit, CrNiC and CrNiCN steels also slide only planarly, even though they are known for wavy slip in the finite life regime above a certain ε a,t [12].…”

Section: Materials Science Aspectsmentioning

confidence: 99%

Fatigue Behavior of Cold-Worked High-Interstitial Steels

Güler

Fischer

2018

Metals

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The austenitic high-nitrogen (AHNS) and high-interstitial steels (AHIS) with more than 0.6 weight-% N allow for a yield strength above 1.1 GPa and a tensile strength above 1.5 GPa by maintaining an elongation to fracture markedly above 30%. These steels gain their prominent mechanical properties from the fact that at the chosen sum of C+N and C/N-ratios, the concentration of free electrons is higher compared to that of other steels. Thus, the capacity to dissipate plastic work under monotonic tensile loading is unique. Now, the fatigue limit of austenitic steels in general is mainly governed by the sum of interstitials and should be further improved by cold working. Unfortunately, this is not the case for the AHNS and AHIS and is in contrast to the classical CrNiC-or CrMnC-steels. Thus, tensile and fatigue tests of cold-worked samples were conducted and analyzed by scanning-and transmission-electron microscopy. This paper tries to elucidate the metallurgical reasons, as well as the material engineering aspects, of such peculiar behavior of AHNS and AHIS.

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“…The fatigue resistance of forged alloys is considerably higher than that of cast alloys; for example, the fatigue strength of forged Co–Cr exceeds 600 MPa (in air) compared with 300 MPa of cast Co–Cr [9,10,11]. Forged Co–Cr has higher fatigue strength due to the wrought microstructure obtained via solid-state phase transformation from a face-centred cubic to a hexagonal close-packed (HCP) crystal structure during cold working [9,12]; therefore, the fatigue, yield and ultimate tensile strengths of the F799 alloy are approximately twice those of as-cast ASTM F75 [9]. However, for the alloy to be forged easily, its carbon content must be sufficiently low, which compromises the wear resistance [9,12].…”

Section: Introductionmentioning

confidence: 99%

“…Forged Co–Cr has higher fatigue strength due to the wrought microstructure obtained via solid-state phase transformation from a face-centred cubic to a hexagonal close-packed (HCP) crystal structure during cold working [9,12]; therefore, the fatigue, yield and ultimate tensile strengths of the F799 alloy are approximately twice those of as-cast ASTM F75 [9]. However, for the alloy to be forged easily, its carbon content must be sufficiently low, which compromises the wear resistance [9,12]. Meanwhile, because of the brittle nature of the HCP structure, the generation and propagation of cracks are generally accelerated [12].…”

Section: Introductionmentioning

confidence: 99%

Influence of Boron Additions and Heat Treatments on the Fatigue Resistance of CoCrMo Alloys

et al. 2019

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Cobalt-based alloys are widely used in the manufacture of joint prostheses. In this study, the effect of boron additions and heat treatment on the ASTM F75 was evaluated by rotating bending fatigue. The boron ranged from 0.06–1 wt %. The alloys were tested in as-cast and heat-treated conditions. In the as-cast condition, the infinite life was observed at 380 MPa, improving to 433–615 MPa according to the amount of boron added. In the heat treatment condition, the fatigue resistance was improved only in the base alloy. The addition of 0.06 wt % boron and heat treatment led to the same resistance as in the as-cast condition. Adding large amounts of boron combined with heat treatment diminished the fatigue limit. The fracture analysis revealed primarily brittle behaviour with some ductile features even on the same sample; only the heat-treated alloy with 0.06 wt % boron was clearly ductile. This alloy also exhibited notably better toughness to crack propagation.

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Austenitic high interstitial steels vs. CoCrMo – Comparison of fatigue behavior

Cited by 9 publications

References 37 publications

The influence of the nitrogen/nickel‐ratio on the cyclic behavior of austenitic high strength steels with twinning‐induced plasticity and transformation‐induced plasticity effects

The influence of the nitrogen/nickel‐ratio on the cyclic behavior of austenitic high strength steels with twinning‐induced plasticity and transformation‐induced plasticity effects

Fatigue Behavior of Cold-Worked High-Interstitial Steels

Influence of Boron Additions and Heat Treatments on the Fatigue Resistance of CoCrMo Alloys

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