The Experts below are selected from a list of 12288 Experts worldwide ranked by ideXlab platform
Okan Unal - One of the best experts on this subject based on the ideXlab platform.
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effect of severe Shot Peening and ultra low temperature plasma nitriding on ti 6al 4v alloy
Vacuum, 2018Co-Authors: Okan Unal, Erfan Maleki, Remzi VarolAbstract:Abstract In this study, the fatigue behavior of Ti-6Al-4V alloy is tend to be improved by severe plastic deformation via Shot Peening and plasma nitriding. Shot Peening with sub-branches: Conventional Shot Peening (A12-14), severe Shot Peening (A28–30 and A34-36) and rePeening (N6-8) are exposed. Besides plasma nitriding is implemented at 500 °C, 550 °C and 600 °C with the durations of 4, 8 and 16 h. Due to utilization of Shot Peening as prior severe plastic deformation during diffusion of nitrogen, two methods are applied in sequence. Severe Shot Peening forms ultra-fine crystals and oriented grains by disintegrating of α and β phases just below the surface and increases surface roughness. Plasma nitriding temperature increase the compound layer thickness and the treatment leads to vanish of β particles through a certain line for diffusion layer. Prior severe plastic deformation by severe Shot Peening generally triggers the formation of thicker compound layer and emerges distinct diffusion depth with finer and oriented precipitation. The phase's intensity obtained from XRD peaks has been amplified by the application of prior Shot Peening. Each Shot Peening provides fatigue improvement on the other hand plasma nitriding application regardless of being pre or post treatments diminish the fatigue resistance.
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optimization of Shot Peening parameters by response surface methodology
Surface & Coatings Technology, 2016Co-Authors: Okan UnalAbstract:Abstract In this study, the Shot Peening parameters which directly influence the arc height of the Almen strip and its characteristics are optimized within the context of Almen intensity, surface roughness and surface hardness via response surface methodology. Determination of the Almen intensity by trial and error method depending on the experience of the technician (measuring the arc height of Almen strips by changing the parameters repeatedly for each Shot Peening process) makes the optimization approaches valuable. The optimization is considered to perform by selecting surface roughness and surface hardness as the responses in order to classify the Shot Peening processes by taking into consideration of wide range of plastic deformation level. The effect of input parameters air pressure, Shot diameter and Peening duration on the Almen intensity, surface roughness and surface hardness is to be determined by using ANOVA regression analysis. Based on the estimated models, optimum Peening conditions are introduced via response optimizer. The model adequacy is verified by the confirmation tests.
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Novel Type Shot Peening Applications on Railway Axle Steel
Journal of Mineral Metal and Material Engineering, 2016Co-Authors: Okan Unal, Ibrahim Zulcic, Ibrahim Karademir, Remzi Varol, Serkan AtesAbstract:In this study, novel type Shot Peening applications such as severe Shot Peening (SSP) and dual step Peening -DSP- (severe Shot Peening followed by re-Peening -RP-) have been applied to AISI 4340 railway axle steel. Microstructural and mechanical properties are compared with conventionally Shot peened (CSP) ones. The new treatments influence thicker surface layer and improve mechanical properties (microhardness and fatigue) by the way of Almen intensity enhancement. Disadvantageously, SSP increase surface roughness to the values that can be hazardous to the expected fatigue life of critical machine parts. However, DSP reduces the values and new approaches could be designed for making surface roughness values comparable with CSP in the aspect of the experimental outputs.
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surface severe plastic deformation of aisi 304 via conventional Shot Peening severe Shot Peening and rePeening
Applied Surface Science, 2015Co-Authors: Okan Unal, Remzi VarolAbstract:Abstract Air blast conventional Shot Peening (CSP), severe Shot Peening (SSP) and rePeening (RP) as a severe plastic deformation applications on AISI 304 austenitic stainless steel is addressed. Shot peened specimens are investigated based on optical, FESEM and digital microscope. The investigations present the austenite transformation to metastable martensite via mechanical twinning due to plastic deformation with high strain rates. It is found that SSP induces thicker nanograin layer with compared to CSP. In XRD studies, the austenite peaks broaden by means of severe Shot Peening and FWHM increase reveals the grain size reduction below 25 nm regimes on the surface. In EDAX line analysis of CSP specimen, carbon content increase has been detected from deformed layer through the nanocrystalline layer then the content reduces. The carbon segregation takes place due to the energy level distinction between dislocations and Fe C bonds. 3d contour digital microscope studies and roughness investigations reveal that SSP has deleterious side effect on the surface roughness and surface flatness. However, RP is an effective way to reduce the surface roughness to reasonable values.
Remzi Varol - One of the best experts on this subject based on the ideXlab platform.
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effect of severe Shot Peening and ultra low temperature plasma nitriding on ti 6al 4v alloy
Vacuum, 2018Co-Authors: Okan Unal, Erfan Maleki, Remzi VarolAbstract:Abstract In this study, the fatigue behavior of Ti-6Al-4V alloy is tend to be improved by severe plastic deformation via Shot Peening and plasma nitriding. Shot Peening with sub-branches: Conventional Shot Peening (A12-14), severe Shot Peening (A28–30 and A34-36) and rePeening (N6-8) are exposed. Besides plasma nitriding is implemented at 500 °C, 550 °C and 600 °C with the durations of 4, 8 and 16 h. Due to utilization of Shot Peening as prior severe plastic deformation during diffusion of nitrogen, two methods are applied in sequence. Severe Shot Peening forms ultra-fine crystals and oriented grains by disintegrating of α and β phases just below the surface and increases surface roughness. Plasma nitriding temperature increase the compound layer thickness and the treatment leads to vanish of β particles through a certain line for diffusion layer. Prior severe plastic deformation by severe Shot Peening generally triggers the formation of thicker compound layer and emerges distinct diffusion depth with finer and oriented precipitation. The phase's intensity obtained from XRD peaks has been amplified by the application of prior Shot Peening. Each Shot Peening provides fatigue improvement on the other hand plasma nitriding application regardless of being pre or post treatments diminish the fatigue resistance.
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From Conventional Shot Peening to Severe Shot Peening as a Novel Surface Grain Refinement Method
2017Co-Authors: Remzi VarolAbstract:As a mechanical surface treatment Shot Peening process is widely used in industry for last five decade. By multiplying the kinetic energy of Shot impacts with special combinations of Peening parameters is called as Severe Shot Peening (SSP). Recently, SSP processes are also used as a severe plastic deformation method for achieving superior surface properties of peened materials rather than Conventional Shot Peening. Many type of metallic and ceramic materials may be Shot peened. Shot Peening affects fatigue properties, corrosion fatigue, stress corrosion cracking, fretting galling and erosion in peened materails. It has been possible to obtain ultrafine and/or nanostructures on or under the surface with SSP.
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Novel Type Shot Peening Applications on Railway Axle Steel
Journal of Mineral Metal and Material Engineering, 2016Co-Authors: Okan Unal, Ibrahim Zulcic, Ibrahim Karademir, Remzi Varol, Serkan AtesAbstract:In this study, novel type Shot Peening applications such as severe Shot Peening (SSP) and dual step Peening -DSP- (severe Shot Peening followed by re-Peening -RP-) have been applied to AISI 4340 railway axle steel. Microstructural and mechanical properties are compared with conventionally Shot peened (CSP) ones. The new treatments influence thicker surface layer and improve mechanical properties (microhardness and fatigue) by the way of Almen intensity enhancement. Disadvantageously, SSP increase surface roughness to the values that can be hazardous to the expected fatigue life of critical machine parts. However, DSP reduces the values and new approaches could be designed for making surface roughness values comparable with CSP in the aspect of the experimental outputs.
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surface severe plastic deformation of aisi 304 via conventional Shot Peening severe Shot Peening and rePeening
Applied Surface Science, 2015Co-Authors: Okan Unal, Remzi VarolAbstract:Abstract Air blast conventional Shot Peening (CSP), severe Shot Peening (SSP) and rePeening (RP) as a severe plastic deformation applications on AISI 304 austenitic stainless steel is addressed. Shot peened specimens are investigated based on optical, FESEM and digital microscope. The investigations present the austenite transformation to metastable martensite via mechanical twinning due to plastic deformation with high strain rates. It is found that SSP induces thicker nanograin layer with compared to CSP. In XRD studies, the austenite peaks broaden by means of severe Shot Peening and FWHM increase reveals the grain size reduction below 25 nm regimes on the surface. In EDAX line analysis of CSP specimen, carbon content increase has been detected from deformed layer through the nanocrystalline layer then the content reduces. The carbon segregation takes place due to the energy level distinction between dislocations and Fe C bonds. 3d contour digital microscope studies and roughness investigations reveal that SSP has deleterious side effect on the surface roughness and surface flatness. However, RP is an effective way to reduce the surface roughness to reasonable values.
Sébastien Remy - One of the best experts on this subject based on the ideXlab platform.
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Simulation of Shot dynamics for ultrasonic Shot Peening: Effects of process parameters
International Journal of Mechanical Sciences, 2014Co-Authors: Jawad Badreddine, Emmanuelle Rouhaud, Matthieu Micoulaut, Sébastien RemyAbstract:Ultrasonic Shot Peening is a pre-stressing process that enhances the life span of mechanical parts. The spheres constituting the Shot are set in motion with a sonotrode and impact the treated part to generate a compressive residual stress field, hence increasing fatigue life. A model predicting the dynamics of the Shot within the ultrasonic Shot Peening chamber is proposed. The influence of the initial conditions on the Shot dynamics is first studied. The model is then used to obtain predictive values for the impact density and the spatial distribution of the velocity of the spheres before the impacts. The influence of the ultrasonic Shot Peening parameters is also evaluated. The variation of the geometry of the Shot Peening chamber is further considered with the use of a prismatic geometry.
Kenichiro Mori - One of the best experts on this subject based on the ideXlab platform.
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effect of processing temperature on warm Shot Peening of spring steel
Journal of Materials Processing Technology, 2005Co-Authors: Y Harada, Kenichiro MoriAbstract:Abstract Effects of processing temperature on the residual stress and hardness in the warm Shot Peening process of springs were investigated to determine the optimum Shot Peening conditions. Springs made of hard spring steel were heated to facilitate a Shot Peening operation by the decrease in flow stress. In a model experiment using Shots of a large size, the Shot Peening apparatus was covered to keep the processing temperature constant, and the distributions of residual stress and hardness in the peened workpieces were measured. Although the flow stress of the workpiece is decreased by the increase in the processing temperature, the decrease of hardness and residual stress in the workpiece increases. The compressive residual stress and the hardness in the peened workpiece were the highest at a temperature of 200 °C. The optimum temperature was also evaluated in an experiment using an actual Shot Peening apparatus with Shots of an average size.
Duan Xiong - One of the best experts on this subject based on the ideXlab platform.
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Test research of premixed water jet Shot Peening surface roughness
Journal of China Coal Society, 2009Co-Authors: Duan XiongAbstract:Chosen Shot Peening pressure,nozzle scanning velocity,target distance as effect factors,chosen glass pill whose diameter was 0. 25 mm,did Shot Peening test to 45 steel and 2Al1 aluminum alloy material by premixed water jet. Adopted stylus method for measuring Shot Peening surface roughness,observed macroscopically shape character of Shot Peening surface by scanning electron microscope. The result indicates that the surface roughness of peened material obviously augments because of premixed water jet Shot Peening,and surface roughness augments as the increase of Shot Peening pressure and minishs as the increase of scanning velocity,the biggest surface roughness target distance exists. The bar distortion area which is"furrow"shape with approximatively equal width appears on the whole Shot Peening surface,and countless non clearance impacting concave whose shape is anomalous bestrews on the whole Shot Peening surface,roughness curve presents"saw tooth"shape,it quite inosculates with"furrow" shape character on Shot Peening surface.
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Technology of Water Jet Shot Peening at High Pressure
Surface Technology, 2005Co-Authors: Dong Xing, Duan XiongAbstract:The mechanism of the water jet Shot Peening at high pressure is analyzed base on organize structure and mechanics action , and the effect of the multiform water jet Shot Peening is gived. New methods of the pre-mixed water jet and the pre-mixed self-oscillating water jet Shot Peening are put forward. The results show that the technology of water jet Shot Peening at high pressure is advanced and superiority evidence and has expansive application foreground.
