Fatigue strength of ion nitrided steel specimens

Tchankov, D.S.; Dimitrov, Dimitar

doi:10.1504/ijmpt.2000.001231

Cited by 5 publications

(5 citation statements)

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“…Krauss [1] found that although martensite is the major component of hardened high carbon steels, the microstructural system is quite complex and may consist of several other phases such as bainite and retained austenite in a variety of arrangements relative to the martensite. Tchankov and Dimitrov [2] found that high nitrogen phase γ ’‐ ɛ exists in the surface layer of ion‐nitrided specimens and nitrous ferrite may be observed beneath this layer. Nitride particles precipitate along the grain boundaries and in the grain volume.…”

Section: Introductionmentioning

confidence: 99%

Monotonic and Cyclic Deformations of Case‐Hardened Steels Including Residual Stress Effects

Yin

Fatemi

2011

Strain

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Monotonic and cyclic deformations of case‐hardened steel specimens under axial loading were investigated experimentally and analytically. A finite element (FE) model for the case‐hardened specimens was constructed to study multiaxial stresses due to different plastic flow behaviour between the case and the core, as well as to evaluate residual stress relaxation and redistribution subsequent to cyclic loading. The multiaxial stress is shown to increase the effective stress on the surface, and, therefore, unfavourable to yielding or fatigue crack nucleation. The residual stresses are shown to relax or redistribute, even in the elastic‐behaving region, when any part of a case‐hardened specimen or component undergoes plastic deformation. Multi‐layer models were used to analyse and predict monotonic and cyclic deformation behaviours of the case‐hardened specimen based on the core and case material properties, and the results are compared with the experimental as well as FE model results. The predicted monotonic stress–strain curves were close to the experimental curves, but the predicted cyclic stress–strain curves were higher than the experimental curves.

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Section: Introductionmentioning

confidence: 99%

Monotonic and Cyclic Deformations of Case‐Hardened Steels Including Residual Stress Effects

Yin

Fatemi

2011

Strain

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“…Thus, the shallow residual stresses in the material were determined using a PANalytical (XRD) diffractometer by the sin 2 ψ method 28 . The material constants were obtained from previous studies, 29,30 and the Bragg–Brentano configuration was applied for Cu‐Kα radiation (45 kV, 40 mA) in the (211) plane. The residual stress was obtained using the following expression, which is provided in the ASTM E2860 method 31 :

d_{\emptyset ψ} = ([], \frac{1}{2} S_{2}^{(italichkl)} σ_{\emptyset} d_{o} \sin^{2} ψ) - C

Section: Methodsmentioning

confidence: 99%

“…The material constants were obtained from previous studies, 29,30 and the Bragg–Brentano configuration was applied for Cu‐Kα radiation (45 kV, 40 mA) in the (211) plane. The residual stress was obtained using the following expression, which is provided in the ASTM E2860 method 31 :

d_{\emptyset ψ} = ([], \frac{1}{2} S_{2}^{(italichkl)} σ_{\emptyset} d_{o} \sin^{2} ψ) - C

where d ϕψ is the interplanar spacing, and ½ S 2 (hkl) is the value of the elastic constant calculated using the modulus of elasticity obtained by nanoindentation on cross sections at 15 μm from the sample surface of the untreated and the treated samples and the theoretical Poisson's ratio 0.30 for CA6NM martensitic stainless steel, 32 0.26 for ceramic materials treated by thermochemical nitriding 30 and 0.27 for HVOF‐treated materials 29 . Additionally, (hkl) corresponds to the indices of the study plane, σ ϕ is the residual stress, d o is the initial interplanar spacing, ψ is the angle between the specimen surface normal and the scattering vector, that is, the normal to the diffracting plane obtained by XRD, and C is a fitting constant.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, the shallow residual stresses in the material were determined using a PANalytical (XRD) diffractometer by the sin 2 ψ method. 28 The material constants were obtained from previous studies, 29,30 and the Bragg-Brentano configuration was applied for Cu-Kα radiation (45 kV, 40 mA) in the (211) plane. The residual stress was obtained using the following expression, which is provided in the ASTM E2860 method 31 :…”

Section: Determination Of Residual Stressesmentioning

confidence: 99%

See 1 more Smart Citation

Improving fatigue strength of hydromachinery 13Cr‐4Ni CA6NM steel with nitriding and thermal spraying surface treatments

Hernández‐Rengifo

Rodríguez

Coronado

2021

Fatigue Fract Eng Mat Struct

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In this study, the rotating‐bending fatigue behavior in water of a 13Cr‐4Ni martensitic stainless steel as substrate, with two different thermochemical treatments and with a thermal sprayed coating was characterized. Hardness profiles were measured by instrumented nanoindentation. X‐ray diffraction was used to identify the phases and measure the residual stresses, and the fracture micromechanisms were characterized by scanning electron microscopy. The results show increases of 27%, 74%, and 95% in the fatigue strength from WC‐10Co‐4Cr coating, plasma nitriding and salt bath nitrocarburizing, respectively, compared with that untreated material at 106 cycles. The good fatigue behavior of the treated surfaces was found to result from an increase in the surface hardness and the generated compressive stresses that delay crack initiation.

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“…The crack nucleation site was affected by both the duration of treatment and the strain amplitude. Tchankov and Dimitrov 3 found that heterogeneous distribution of nitrogen had significant effects on micro hardness and residual stresses of ion‐nitrided specimens.…”

Section: Introductionmentioning

confidence: 99%

Fatigue behaviour and life predictions of case‐hardened steels

Yin

Fatemi

2009

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper presents experimental and analytical results on fatigue behaviour of casehardened steel. Fully reversed strain-controlled constant amplitude axial fatigue tests were performed on through-hardened case, through-hardened core and case-hardened steel specimens. Surface versus sub-surface cracking and the role of residual stresses and their relaxation are discussed. Multi-layer models of the case-hardened specimens were used to predict crack nucleation sites as well as fatigue lives, and the predictions corresponded well with the experimental results. Linear elastic fracture mechanics (LEFM) was also used to conduct fatigue crack growth analysis to further explain the experimental observations from the fracture surfaces of the case-hardened specimens. A fatigue strength estimation method based on hardness and inclusion size was used to estimate the fatigue limit of the materials investigated. Fractography of fracture surfaces and crack nucleation location are also presented.

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Fatigue strength of ion nitrided steel specimens

Cited by 5 publications

References 0 publications

Monotonic and Cyclic Deformations of Case‐Hardened Steels Including Residual Stress Effects

Monotonic and Cyclic Deformations of Case‐Hardened Steels Including Residual Stress Effects

Improving fatigue strength of hydromachinery 13Cr‐4Ni CA6NM steel with nitriding and thermal spraying surface treatments

Fatigue behaviour and life predictions of case‐hardened steels

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