Peening

About: Peening is a research topic. Over the lifetime, 5538 publications have been published within this topic receiving 73073 citations.

Rehabilitation and repair of welded elements and structures by ultrasonic peening

Abstract: The Ultrasonic Peening (UP) is the most efficient technique for increasing the fatigue life of welded elements as compared to such existing improvement treatments as grinding, TIG-dressing, shot peening, hammer peening, etc. The results of experimental investigation of the efficiency of UP for rehabilitation and repair of welded elements and structures with the goal of preventing the origination and propagation of fatigue cracks are considered in this document. UP treatment was applied to large-scale welded specimens in as-welded condition, after 50 % of expected fatigue life and after repair of fatigue cracks. Also, different techniques for restraining and repair of fatigue cracks were analyzed and compared: overloading; drilling of the crack tips; drilling of the crack tips with installation of high strength bolts; local explosive treatment; local heat treatment; welding with and without UP of weld toe zones. As an example, the practical application of UP for rehabilitation and repair of welded elements of highway and railway bridges are also discussed.

Effects of surfaces nanocrystallization induced by shot peening on material properties : a Review

Abstract: A brief description of surface nanosrystallization process via severe plastic deformation is presented. To come to the point different shot peening methods which have proved to be able to create nanocrystalline layers are demonstrated clarifying the actual state of the art. Then the influence of the process is reviewed on material behavior and a wide range of affected properties are investigated. On this basis some possible addresses for future research in this field are drawn and underlined.

Compound technology of manufacturing and multiple laser peening on microstructure and fatigue life of dual-phase spring steel

Abstract: The present work proposes an advanced double quenching and tempering heat treatment based laser surface modification process of dual-phase spring steel. Multiple laser peening without coating process utilized the decarburized surface as the protective layer for the further cold working process. The electron backscattering diffraction analysis on crystallographic orientation of individual grains and phase map exhibits a perfect dual-phase steel. Also, the high resolution transmission electron microscopic study explains the high strain induced microstructural grain refinement features and plastic deformation behaviors. The laser peening technique taking an advantage that it induces a large and high magnitude compressive residual stress with good thermal stability. The micro and nano-hardness profile provides better surface and sub-surface mechanical properties. The controlled average surface roughness is achieved in this course of work. The stress-strain characteristics on tensile properties are analyzed through the pre-fatigued specimens. The fully reversed high cycle fatigue test indicates that the current laser peening has substantially improves the fatigue life of the specimens.

A comparison of AA2024 and AA7150 subjected to ultrasonic shot peening: Microstructure, surface segregation and corrosion

Abstract: The influence of ultrasonic shot peening (USSP) on microstructure, surface segregation, localized and electrochemical corrosion of AA2024 was investigated using immersion test, OCP, EIS, polarization, XRD and SEM-EDS methods. The results are compared with those of AA7150. Like AA7150, second phase particles of AA2024 peened surface layer dissolved into Al matrix due to the extended solid solubility caused by USSP. After USSP, corrosion rate of AA2024 increased by 2–3 times due to surface contamination, however, intergranular corrosion (IGC) resistance of AA2024 is significantly enhanced by USSP treatment. The improvement in localized corrosion resistance is mainly attributed to grain refinement and microstructure homogenization. As opposed to AA7150, OCP of AA2024 in 3.5 wt% NaCl solution (pH = 5.8) shifts to more noble direction after USSP. This is due to the different surface segregation behaviours of the two studied alloys. The mechanism of surface segregation is also briefly discussed.

Investigation of shot-peened austenitic stainless steel 304L by means of magnetic Barkhausen noise

Abstract: Different shot peening conditions were applied to an austenitic stainless steel AISI 304L in order to transform austenite to martensite α′ at different depths. Magnetic Barkhausen noise measurements performed on this steel reveal a correlation between the strength of the signal and the depth of the treatment. The combined effect of the volume fraction of martensite and the residual stress in martensite determined using X-ray diffraction analysis were found to be responsible for the evolution of the Barkhausen noise response. Using tensile plastic deformation, the residual stress in martensite was changed, giving rise to a strong increase of the Barkhausen noise activity. This variation was correlated to a modification of the sign and amplitude of the residual stress in the martensite phase. Directional measurements of the Barkhausen noise revealed the anisotropy of the residual stresses induced by the tensile plastic deformation. It is concluded that the Barkhausen noise activity recording could lead to the determination of the residual stresses in martensite induced by shot peening processes.