Measurement and tailoring of residual stress in expanded austenite on austenitic stainless steel

Fernandes, Frederico Augusto Pires; Christiansen, Thomas; Winther, Grethe; Somers, Marcel A. J.

doi:10.1016/j.msea.2017.06.082

Cited by 16 publications

(16 citation statements)

References 24 publications

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“…15c was previously published in Ref. [26], but the occurrence of tensile stress induced cracks remained unobserved. Unfortunately, in Ref.…”

Section: Discussionmentioning

confidence: 96%

“…9 (from Ref. [26]). The horizontal arrows indicate the locations of cracks that were most likely initiated by the introduction of tensile stress in the plastically deformed region caused by de-nitriding.…”

Section: Discussionmentioning

confidence: 99%

“…Unfortunately, in Ref. [26] the micrographs in Fig. 1 for nitrided and de-nitrided expanded austenite were swapped.…”

Section: Discussionmentioning

confidence: 99%

“…9a) give −5 GPa for the nitrided condition to −100 MPa (virtually zero stress) for the subsequently de-nitrided condition. Evidently, removing the composition profile in the first 12 μm of the expanded austenite zone by de-nitriding leads to removal of elastic residual stress at the surface [26]. Most likely the virtually zero-stress state extends to the entire zone where the nitrogen content is constant (see Fig.…”

Section: Grazing-incidence X-ray Diffraction At Variable Incidence Anmentioning

confidence: 95%

“…(b) GD-OES nitrogen depth profiles of nitrided and subsequently de-nitrided specimens. (c) Corresponding hardness-depth profiles show only a small decrease in hardness on de-nitriding (data from Ref [26]…”

mentioning

confidence: 99%

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Residual Stress in Expanded Austenite on Stainless Steel; Origin, Measurement, and Prediction

Somers

Kücükyildiz

Ormstrup

et al. 2018

Materials Performance and Characterization

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Expanded austenite is a supersaturated solid solution of nitrogen/carbon in austenite that forms as a case by the diffusion of nitrogen/carbon into austenitic stainless steel. Expanded austenite has a high level of hardness that provides resistance against galling and wear, superior resistance against localized corrosion, and contributes to improvement of the fatigue performance. This latter characteristic is a consequence of the huge compressive residual stresses in the expanded austenite case. Such stresses are induced by the high interstitial content in the austenite lattice and are accommodated elasto-plastically. The experimental assessment of the elastic lattice strains is complicated by the presence of steep composition-depth and stress-depth profiles, which necessitate special measurement or correction procedures to unravel the influence of composition and stress on the lattice spacing and avoid artifacts arising from (steep) lattice-spacing gradients. In the present work the sin 2 ψ method was combined with grazing incidence X-ray diffraction to keep the information depth during measurement shallow, independent of the (effective) tilt angle ψ. The plastic strains in the expanded austenite 27 zone were estimated from the lattice rotations, as determined with electron backscatter diffraction. It is demonstrated that the level of elastic lattice strains in expanded austenite can be adjusted by retracting part of the dissolved nitrogen. The experimental results for elastic and plastic strains are compared to those predicted by a comprehensive numerical Manuscript

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“…15c was previously published in Ref. [26], but the occurrence of tensile stress induced cracks remained unobserved. Unfortunately, in Ref.…”

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

“…Unfortunately, in Ref. [26] the micrographs in Fig. 1 for nitrided and de-nitrided expanded austenite were swapped.…”

Section: Discussionmentioning

confidence: 99%

Section: Grazing-incidence X-ray Diffraction At Variable Incidence Anmentioning

confidence: 95%

mentioning

confidence: 99%

See 3 more Smart Citations

Residual Stress in Expanded Austenite on Stainless Steel; Origin, Measurement, and Prediction

Somers

Kücükyildiz

Ormstrup

et al. 2018

Materials Performance and Characterization

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A Novel Concept of Hybrid Treatment for High‐Hardenability Steels: Concomitant Hardening and Paraequilibrium Thermochemical Treatment to Produce Interstitially Hardened/Stabilized Austenite Surfaces

Toscano

Cardoso

Brunatto

2020

steel research int.

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Steel components' performance requirements are being strongly increased due to the technological evolution of machines. In most of the cases, surface and bulk material requirements are extremely different, so, an optimised component should present different surface and bulk properties. In such a context, the application of surface engineering processes becomes unavoidable and, to achieve the desired performance at acceptable cost, frequently, new materials and/or processing routes are necessary. The novel concept of hybrid treatment proposed here makes possible to obtain components with such characteristics in a single thermal cycle. So it should be a powerful tool helping to overcome the challenges imposed to the metallurgical industry to produce components that present simultaneously high strength and wear and corrosion resistances at lower costs. This process is the subject of a pending patent BR1020180150758 [1] and this communication has the objective of presenting the new hybrid treatment concept, proving its feasibility by means of a case study. The hybrid process, applicable to highhardenability steels, consists in carrying out a thermochemical treatment during the isothermal step of the martempering or austempering hardening treatment (see Figure 1), above the martensite start temperature and so in the metastable austenite field. Thus, this process combines a surface treatment and a substrate bulk treatment, in a same thermal cycle, probably leading to the reduction of the treatment costs as a whole (hardening plus thermochemical treatment). In addition, it enables to produce a hard interstitially hardened/stabilized austenite treated surface, supposedly presenting higher wear and corrosion resistances than the substrate bulk material. In this concept, depending on the steel hardenability and the chosen processing parameters, the bulk material can be either martensitic or bainitic. The stabilized austenite surface can be produced by paraequilibrium nitriding or carburizing thermochemical treatment. The new concept of hybrid treatment is schematically shown in Figure 1. The first step consists in heating a high-hardenability steel component until the austenitizing temperature, waiting for its complete transformation to stable austenite, and this is the "zero" time point in the Figure 1 scheme. In the sequence, the component/part is cooled down to a temperature that enables the paraequilibrium thermochemical treatment to be conducted, in the metastable austenite field, avoiding the martensitic transformation. The paraequilibrium thermochemical treatment step, in the present case nitriding, is successfully performed at temperatures usually below 420 C for austenitic steels. [2-4] As soon as the paraequilibrium thermochemical treatment step is concluded, the component/part can be cooled down to the room temperature. The last cooling step can produce different microstructure in the component bulk (see Figure 1): 1) for the process ending in "A", a martensitic bulk material will be produced;

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Greater diffusion rate of carbon atoms from nonlinear migration in micro-cell and spatially heterogeneous stable states in FCC iron

Wang

Qing

et al. 2018

J Mater Sci

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Measurement and tailoring of residual stress in expanded austenite on austenitic stainless steel

Cited by 16 publications

References 24 publications

Residual Stress in Expanded Austenite on Stainless Steel; Origin, Measurement, and Prediction

Residual Stress in Expanded Austenite on Stainless Steel; Origin, Measurement, and Prediction

A Novel Concept of Hybrid Treatment for High‐Hardenability Steels: Concomitant Hardening and Paraequilibrium Thermochemical Treatment to Produce Interstitially Hardened/Stabilized Austenite Surfaces

Greater diffusion rate of carbon atoms from nonlinear migration in micro-cell and spatially heterogeneous stable states in FCC iron

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