Peening

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

Gas turbine engine rotor blades

Abstract: A component for a gas turbine engine having at least one surface, that has been treated by ultrasonic hammer peening so as to provide a region of deep compressive residual stress in the treated region.

Thermal relaxation of residual stresses in shot peened surface layer of (TiB + TiC)/Ti–6Al–4V composite at elevated temperatures

Abstract: As an effective and important surface treatment method, shot peening can introduce high residual compressive stress and microstructure variation at near surface deformation layers. In this work, residual stresses relaxation behaviors of the shot peened layer of (TiB + TiC)/Ti–6Al–4V composite were investigated during thermal exposure, and the microstrain was calculated according to the integral breadth after isothermal annealing. The microstrain decreased fast and reached the minimum at 500 °C, which resulted from the thermal recovery and dynamic recrystallization. At elevated temperatures, the residual compressive stresses were relaxed in the whole deformation layers, which were caused by the thermally activated gliding of dislocations. The processes of relaxation can be described using a Zener–Wert–Avrami function and the activation energy of the residual stresses relaxation was higher than that of titanium self diffusion, which was ascribed to the hindrance effects of reinforcements as sink sources of dislocations during annealing.

Laser shock peening and its effects on microstructure and properties of additively manufactured metal alloys: a review

Abstract: This review paper discusses the recent progress in laser shock peening (LSP) of additively manufactured (AM) parts. LSP is an advanced post-processing technique that optimizes the service lives of critical components for various applications by inducing severe plastic deformation accompanied by the enhancement of surface properties in treatedmaterials.Material improvement is enabled through the generation of high-density dislocations, grain refinement, and beneficial phase transformations. Thesemechanisms produce highmagnitude compressive residual stresses which harden treated regions to depths exceeding 1mm.However, amajor roadblock for AMparts stems from the various fabrication processes themselves where detrimental tensile residual stresses are introduced during partmanufacturing, alongwith near-surface voids and cracks, all of which severely limit their applications. In addition to post-fabrication heat treatment that is typically required to homogenize themicrostructure and relieve the residual stresses of AMparts, post-processing surface treatments have also been developed tomanipulate the residual stresses of AMmaterials. Tensile residual stresses generated duringmanufacturing affect the fatigue life of AMmaterial negatively and could potentially surpass thematerial’s yield strength, resulting in acute geometric distortion. Recent studies have shown the potential of LSP tomitigate these stresses,modify themechanical properties of theAMparts, and to close near-surface voids and cracks. Furthermore, the thermal stability of favorablemicrostructuralmodifications in laser peenedAMparts, which allows for its use in high temperature environments, is not well understood and is currently limiting its effective utilization in these scenarios. Themain goal of this review is to provide the detailed insight needed for widespread acceptance of this technique as a post-processingmethod for AMmaterials.

Dynamic response and residual stress fields of Ti6Al4V alloy under shock wave induced by laser shock peening

Abstract: Laser shock peening (LSP), an innovative surface treatment technique, generates compressive residual stress on the surface of metallic components to improve their fatigue performance, wear resistance and corrosion resistance. To illustrate the dynamic response during LSP and residual stress fields after LSP, this study conducted FEM simulations of LSP in a Ti6Al4V alloy. Results showed that when power density was 7 GW cm−2, a plastic deformation occurred at 10 ns during LSP and increased until the shock pressure decayed below the dynamic yield strength of Ti6Al4V after 60 ns. A maximum tensile region appeared beneath the surface at around 240 ns, forming a compressive-tensile-compressive stress sandwich structure with a thickness of 98, 1020 and 606 μm for each layer. After the model became stabilized, the value of the surface residual compressive stress was 564 MPa at the laser spot center. Higher value of residual stress across the surface and thicker compressive residual stress layers were achieved by increasing laser power density, impact times and spot sizes during LSP. A 'Residual stress hole' occurred with a high laser power density of 9 GW cm−2 when laser pulse duration was 10 ns, or with a long laser pulse duration of 20 ns when laser power density was 7 GW cm−2 for Ti6Al4V. This phenomenon occurred because of the permanent reverse plastic deformation generated at laser spot center.