Sharif Digital Repository

Mechanical failures in most cases originate from the exterior layers of the components. It is considerably effective to apply methods and treatments capable to improve the mechanical properties on component’s surface. Surface nanocrystallization produced by severe plastic deformation (SPD) processes such as severe shot peening (SSP) is increasingly considered in the recent years. However, artificial intelligence systems such as artificial neural network (ANN) as an efficient approach instead of costly and time consuming experiments is widely employed to predict and optimize the science and engineering problems in the last decade. In the present study the application of ANN in predicting of... 

Severe plastic deformation methods such as severe shot peening are used in order to improve mechanical properties of the components by surface microstructure nanocrystallization. Severe shot peening is one of the popular mechanical surface treatments generally aimed at generating nanograined layer and compressive residual stress close to the surface. Moreover, artificial neural network has been used as an efficient approach to predict and optimize the engineering problems. In present study effects of conventional and severe shot peening on cast iron were modelled by means of artificial neural networks and they were compared. The obtained results indicate that severe shot peening has superior... 

Shot peening (SP), as one of the severe plastic deformation (SPD) methods is employed for surface modification of the engineering components by improving the metallurgical and mechanical properties. Furthermore, artificial neural network (ANN) has been widely used in different science and engineering problems for predicting and optimizing in the last decade. In the present study, effects of conventional shot peening (CSP) and severe shot peening (SSP) on properties of AISI 1060 high carbon steel were modelled and compared via ANN. In order to networks training, the back propagation (BP) error algorithm is developed and data of experimental tests results are employed. Experimental data... 

This study involves the capability of severe shot peening (SSP) as a catalyst intake for plasma nitriding process and the probability of reducing the requirement of thermal energy individually on the diffusion of interstitial atoms. To this end, combination of mechanical-thermal energy is run with pure thermal plasma assisted energy. Therefore, SSP is exposed to AISI 304 austenitic stainless steel as a former treatment and gradient structured surface (nanograined zone, ultrafine grain martensite-twin intersections zone and twin densed zone) is created. Then, plasma nitriding at 400 0 C-4h and 475 0 C-2h temperature-duration conditions. The condition of 475 0 C-2h provides the requirements of... 

AA7075 alloy is exposed to severe shot peening (SSP) with an Almen intensity of 20A. The microstructure is analyzed via FEGSEM and EBSD microscopy. X-ray diffraction (XRD) analysis is used to evaluate the crystallite size in terms of FWHM measurements. The residual stress measurements show a thicker compressed layer (600 µm) formed by SSP. Microhardness improvements are observed as 30% on topmost surface and releases substantially after 600 µm. Coefficient of friction (COF) of treated material remains higher throughout the sliding distance, however, is reduced particularly in the early stage of sliding distance for the wear load of 20 N. The effect of SSP is vanished particularly at lower... 

This paper presents the influence of the severe shot peening process on the fatigue life of the laser-cladded Inconel 718 specimens which can be employed during refurbishment of components enduring high mechanical cyclic loads such as gas turbine components. In order to quantitatively evaluate the destructive effect of laser cladding on the fatigue endurance, fatigue tests are first performed on the as-received and laser-cladded specimens. Then, microstructural analysis by scanning electron microscope (SEM) is carried out to identify the root causes of the drawback of laser cladding. Moreover, by employing a comprehensive laser-cladding FE analysis considering cyclic plastic material... 

The effects of severe shot-peening process and formation of a nanostructured surface layer on mechanical properties of A356.0 alloy were investigated in this paper. X-ray diffraction analyses revealed that the average size of near-surface grains in severe shot-peened specimens is 75.8 nm. Three types of disk-shaped specimens, non-treated, conventionally shot-peened, and severely shot-peened were subjected to pin-on-disk wear test in the dry condition, in different loading and sliding speeds. Shot-peening process increases both hardness and roughness of the surface, and these two factors have, respectively, positive and negative effects on wear resistance. However, because of high-density...