Yazarlar
Yayınlar
- MakaleYayıncıda açık erişim2026Scopus SJRQ1Surface modification and tribological performance of AISI 4140 steel via shot peening and plasma nitriding: A systematic evaluation of conventional, repeated and severe plastic deformation
Erdoğan, Ömer; Kovacı, Halim
Despite its widespread industrial use, AISI 4140 steel exhibits limited resistance to wear and surface damage. This study investigates the effects of vibratory shot peening and plasma nitriding processes, applied individually and in combination, on the tribological performance of AISI 4140 steel. Shot peening was performed under conventional (CSP), re-shot peening (RSP) and severe shot peening (SSP) conditions, while plasma nitriding was carried out at temperatures of 460 °C and 535 °C. The severe plastic deformation created by shot peening increased dislocation density, significantly improving nitrogen diffusion during plasma nitriding. The SSP condition resulted in the highest surface hardness, increasing from 248 HV0.1 to 533 HV0.1, while the combined SSP and plasma nitriding treatment produced a maximum hardness of 920 HV0.1. In dry wear tests, the combined application of shot peening and plasma nitriding significantly reduced the wear rate, achieving a reduction of approximately 94% compared to the untreated sample. In saltwater environments, wear behaviour was controlled by the continuity of the nitride layer and the diffusion depth, resulting in an 82% reduction in wear rate for the SSP and plasma nitriding condition. Overall, it has been observed that applying vibratory shot peening prior to plasma nitriding significantly improves the tribological performance of AISI 4140 steel.
- MakaleAçık Erişim2015Scopus SJRQ1Numerical modeling of cold powder compaction using multi particle and continuum media approaches
Güner, Faruk; Cora, Ömer Necati; Sofuoğlu, Hasan
Numerical analysis of powder compaction process requires multi-particle modeling approach as continuum models fail to simulate the nature of process (e.g. interparticle, and particle-die interactions), accurately. This study aimed for analyzing powder compaction process utilizing 3-D finite element modeling approach along with different material models including modified Cam-Clay, Mohr-Coulomb, Shima-Oyane and von-Mises. The finite element analyses were carried out by implementing multi-particle finite element method. Moreover, continuum modeling was also performed for comparison purposes. In both cases, the compaction of spherical copper particles was analyzed at room temperature conditions. The obtained FEA results were compared in terms of equivalent stress and strain, and deformed shape. Results showed that the FE models in which von-Mises and modified Cam-clay material models were used yielded results of similar magnitude while those of Shima-Oyane and Mohr-Coulomb material models resulted in equivalent stress and strain values are in close proximity. Effect of coefficient of friction on the results was also investigated by implementing three distinct coefficients of friction ( μ= 0.1, 0.25, 0.4). It was noted that increasing friction resulted in elevated level of deformation for the particles and harsher particle-particle, and particle-die contact interactions.
AtıfScopus72WoS67OpenAlex76
İncele