Effects of shot peening and artificial surface defects on fatigue properties of 50CrV4 steel (original) (raw)
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Fatigue behavior of a low-alloy steel with nanostructured surface obtained by severe shot peening
Engineering Fracture Mechanics, 2012
Severe shot peening aimed to generate a nanograined layer over specimens' surface has been applied by means of standard air blast equipment but using peening parameters essentially different from typical ones. Different experimental processes including microscopy observation, microhardness, roughness and X-ray diffraction measurements have been performed to characterize the treated surface of specimens. The results confirm the generation of a nanocrystallized surface layer. Rotating bending fatigue tests are then performed on smooth specimens to evaluate the effect of the nanocrystallized layer on fatigue strength. The results indicate improvement of fatigue life notwithstanding the specimen's very high surface roughness: a refinement of the treatment parameters aimed at reducing the roughness is proposed.
Fatigue behavior of X70 microalloyed steel after severe shot peening
International Journal of Fatigue, 2013
The so called ''severe plastic deformation'' (SPD) processes are object of increasing interest due to their ability to obtain a nanostructured surface layer of material with supposed superior properties. Among these processes, severe shot peening (SSP) is very attractive from an industrial point of view, due to its versatility and wide applicability.
Metals and Materials International
This study investigates and compares the effects of different shot peening treatments including conventional and severe shot peening on microstructure, mechanical properties, fatigue behavior, and residual stress relaxation of AISI 1060 steel. Shot peening treatments were applied with two Almen intensities of 17 and 21 A and a wide ranges of coverage (100%–1500%). Various microstructural observations were carried out to analyze the evolution of microstructure. Microhardness, residual stress and surface roughness measurements and also axial fatigue test were performed. Moreover, the extent of the residual stress relaxation during cyclic loading was investigated by means of XRD measurements. Furthermore, numerical simulation of residual stress relaxation due to fatigue loading was carried out and validated against experimental investigations. The comparison indicated a good agreement for the surface residual stress relaxation up to 100 cycles. The experimental results indicated the ef...
Fatigue behaviour of a low-alloy steel with a nanostructured surface obtained by severe shot peening
Engineering Fracture Mechanics, 2011
Severe shot peening aimed to generate a nanograined layer over specimens' surface has been applied by means of standard air blast equipment but using peening parameters essentially different from typical ones. Different experimental processes including microscopy observation, microhardness, roughness and X-ray diffraction measurements have been performed to characterize the treated surface of specimens. The results confirm the generation of a nanocrystallized surface layer. Rotating bending fatigue tests are then performed on smooth specimens to evaluate the effect of the nanocrystallized layer on fatigue strength. The results indicate improvement of fatigue life notwithstanding the specimen's very high surface roughness: a refinement of the treatment parameters aimed at reducing the roughness is proposed.
Malaysian Journal of Fundamental and Applied Sciences, 2018
ASTM A516 Grade 70 is widely used in the industrial sector as it provides very good mechanical properties in tough conditions. The main usage of this material is in moderate and low operating services. This paper focuses on the effect of shot peening process on ASTM A516 Grade 70 on improving the mechanical properties and fatigue life of the material. Samples have been shot peened with steel shot to induce compressive residual stress. Hardness, tensile and fatigue test as well as microstructure were done on the samples before and after shot peening process to study the effects on mechanical properties. The result shows that there is an increment in every test after shot peening process. There is a slight increment of 0.47% in hardness value, 0.39% increment in tensile strength and 6.78% increment in fatigue life of the material after shot peening process applied. The slight increment in every result was due to the low intensity of the shot peening process. Result also shows that the...
Materials and Design, 2013
Among severe plastic deformation methods that result in surface nanocrystallization, shot peening has proved to be a promising technique. Application of severe air blast shot peening results in surface nanocrystallization, affects a thick layer of material with high compressive residual stresses but at the same time produces rather high surface roughness. In this study notched specimens with a stress concentration factor common in many structural components have been subjected to severe shot peening process. The mentioned treatment uses peening parameters essentially different from conventional ones. Roughness and X-ray diffraction residual stress measurements as well as microscopy observations have been carried out on the treated specimens. Room temperature rotating bending fatigue tests are performed to evaluate the effect of the treatment on specimens' fatigue strength. Fracture surfaces have been then observed by scanning electron microscopy. The results indicate a very significant fatigue strength improvement for severely shot peened specimens in spite of their very high surface roughness.
International Journal of Fatigue, 2013
The plastic deformation resulting from shot peening treatments applied to the ferritic heat resistant steel FV448 has been investigated. Two important effects have been quantified: surface roughness and strain hardening. 2D and 3D tactile and optical techniques for determining surface roughness amplitude parameters have been investigated; it was found that whilst R a and S a were consistent, S z was generally higher than R z due to the increased probability of finding the worst case surface feature. Three different methods for evaluating the plastic strain profile have been evaluated with a view to establishing the variation in yield strength near the surface of a shot peened component. Microhardness, X-ray diffraction (XRD) line broadening and electron backscatter diffraction (EBSD) local misorientation techniques were applied to both uniaxially deformed calibration samples of known plastic strain and samples shot peened at intensities varying from 4A to 18A to establish the variation in plastic strain and hence the variation in yield strength. The results from the three methods were compared; XRD and EBSD profiles were found to be the most similar with microhardness profiles extending much deeper into the sample. Changes in the measured plastic strain profile after exposure to low cycle fatigue and the correlation of these changes with the cyclic stress-strain behaviour of the material are also discussed with a view to assessing the importance of the dislocation profile in component life assessment procedures.
International Journal of Fatigue, 2014
Fatigue strength of mechanical components can be greatly enhanced by generating compressive residual stress, increasing the hardness and reducing the grain size. It is well known that while the use of mechanical treatments is able to generate an effective field of compressive residual stresses and, if severe parameters are used, to cause grain refinement, thermochemical treatments are able to increase the surface hardness. This justifies the interest in developing combined treatments, able to achieve all the just mentioned factors.