Experimental Examination of Surface  Micro-Hardness Improvement Ratio  in Burnishing of External Cylindrical Workpieces

Varga, Gyula; Ferencsik, Viktoria

doi:10.20998/2078-7405.2020.93.13

Cited by 4 publications

(1 citation statement)

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“…In recent years, many studies have been devoted to improving the surface integrity (SI) and operating behavior (wear, corrosion and fatigue resistance) of CNASS components by means of static SCW methods: ball burnishing [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], roller burnishing [6,[22][23][24][25] and DB [2][3][4][26][27][28][29][30][31][32][33][34][35]. There are relatively few studies devoted to improvement in the fatigue behavior of CNASS components by means of SCW [2][3][4][8][9][10][11][12][13]18,23].…”

Section: Introductionmentioning

confidence: 99%

Improvement in Fatigue Strength of Chromium–Nickel Austenitic Stainless Steels via Diamond Burnishing and Subsequent Low-Temperature Gas Nitriding

Maximov,

Duncheva,

Anchev

et al. 2024

Applied Sciences

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Chromium–nickel austenitic stainless steels are widely used due to their high corrosion resistance, good weldability and deformability. To some extent, their application is limited by their mechanical characteristics. As a result of their austenitic structure, increasing the static and dynamic strength of the components can be achieved by surface cold work. Due to the tendency of these steels to undergo intercrystalline corrosion, another approach to improving their mechanical characteristics is the use of low-temperature thermo-chemical diffusion processes. This article proposes a new combined process based on sequentially applied diamond burnishing (DB) and low-temperature gas nitriding (LTGN) to optimally improve the fatigue strength of 304 steel. The essence of the proposed approach is to combine the advantages of the two processes (DB and LTGN) to create a zone of residual compressive stresses in the surface and subsurface layers—the enormous surface residual stresses (axial and hoop) introduced by LTGN, with the significant depth of the compressive zone characteristic of static surface cold working processes. DB (both smoothing and single-pass hardening), in combination with LTGN, achieves a fatigue limit of 600 MPa, an improvement of 36.4% compared to untreated specimens. Individually, smoothing DB, single-pass DB and LTGN achieve 540 MPa, 580 MPa and 580 MPa, respectively. It was found that as the degree of plastic deformation of the surface layer introduced by DB increases, the content of the S-phase in the nitrogen-rich layer formed by LTGN decreases, with a resultant increased content of the ε-phase and a new (also hard) phase: stabilized nitrogen-bearing martensite.

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Section: Introductionmentioning

confidence: 99%

Improvement in Fatigue Strength of Chromium–Nickel Austenitic Stainless Steels via Diamond Burnishing and Subsequent Low-Temperature Gas Nitriding

Maximov,

Duncheva,

Anchev

et al. 2024

Applied Sciences

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Explicit correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

Maximov,

Duncheva,

Anchev

et al. 2024

Int J Adv Manuf Technol

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Direct correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

Maximov,

Duncheva,

Anchev

et al. 2023

Preprint

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Direct correlations were established between basic surface integrity (SI) characteristics (roughness, microhardness, residual stresses) obtained as a result of surface cold working (SCW) and bending fatigue limit of chromium-nickel austenitic stainless steels (CNASS). The results of experimental tests and optimization of the SCW process, implemented via hardening diamond burnishing (DB), are presented. When the requirement for the corresponding component is a high fatigue limit, the information obtained will help the researcher to find the inverse correlation between SI and finishing so that when the SCW process is implementing by another method, the same high fatigue limit can be achieved. Five roughness parameters that are functionally significant indicators of fatigue behavior, microhardness, and surface residual axial and hoop stresses form the vector of objective functions. The governing factors are the burnishing force and the number of passes. The fatigue limit was obtained by the accelerated Locati’s method. The models of the corresponding SI characteristics and the fatigue limit were obtained by a planned experiment and regression analyses. Direct correlations between SI characteristics and the fatigue limit were obtained by eliminating the variables in the corresponding pairs of models. The change trends of the microhardness and fatigue limit were found to be identical, i.e., the fatigue limit of CNASS can be controlled via inexpensively measured SI characteristics such as roughness parameters and surface microhardness. In other words, any static coldworking process can be optimized without carrying out fatigue tests by choosing these SI characteristics as objective functions and seeking a compromise optimal solution that simultaneously achieves high values of the microhardness and skewness and a low value of the roughness parameter Ra. Given the direct correlation between the microhardness and the fatigue limit, the compromise optimal solution maximizes the fatigue limit while satisfying the particular roughness requirements. The multi-objective optimization performed and comparisons made prove the effectiveness of the proposed approach.

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Experimental Examination of Surface Micro-Hardness Improvement Ratio in Burnishing of External Cylindrical Workpieces

Cited by 4 publications

References 0 publications

Improvement in Fatigue Strength of Chromium–Nickel Austenitic Stainless Steels via Diamond Burnishing and Subsequent Low-Temperature Gas Nitriding

Improvement in Fatigue Strength of Chromium–Nickel Austenitic Stainless Steels via Diamond Burnishing and Subsequent Low-Temperature Gas Nitriding

Explicit correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

Direct correlation between surface integrity and fatigue limit of surface cold worked chromium-nickel austenitic stainless steels

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