Laser-shock-peening technology is an international research hotspot in the surface-strengthening field, which utilizes the mechanical effects of laser-induced plasma shock waves to effectively improve the fatigue performance of metallic components by introducing the gradient microstructures and compressive residual stress into the surface layer of processed materials. The fatigue failure caused by high-frequency vibrations in aeroengines during service is the most important threat to flight safety, and this case is more prominent for military aeroengines because their service situation is harsher. The present paper focuses on components such as high-temperature components, fan/compressor blade, and thin-walled weldments, and it systematically introduces the researching findings about surface nanocrystallization and compressive residual stress formation mechanism in typical aeronautical metallic materials treated by laser shock peening. The contents mainly involve the characteristics, formation process, fatigue resistance mechanism, thermal stability of residual compressive stress, and nanocrystallization generated by laser shock peening.

https://www.mdpi.com/2075-4701/13/5/979/pdf?version=1684486154

Review on Anti-Fatigue Performance of Gradient Microstructures in Metallic Components by Laser Shock Peening

This study aimed to identify the optimal combination of wavelength and laser pulse density to achieve the optimal pulse pressure that can induce the maximum compressive residual stress at the subsurface of microalloyed steel. For this, laser shock peening without coating (LSPwC) was performed on microalloyed steel samples at the fundamental wavelength (1064 nm) with pulse densities of 3, 6, 9, and 12 GW/cm2 and at the second harmonic wavelength (532 nm) with pulse densities of 3, 6, and 9 GW/cm2. The residual stress distributions were studied to a depth of 500 µm in the laser-treated samples. Tensile residual stress was observed at the surface of laser-peened specimens in both wavelength conditions (1064 and 532 nm). The significant impartment of compressive residual stress across the depth was achieved at the fundamental wavelength (1064 nm). The maximum compressive residual stress was attained with a laser pulse density of 9 GW/cm2 in the 1064nm wavelength condition. The optical micrographic analysis in the subsurface regions of the LSPwC specimen at 1064 nm and 9 GW/cm2 shows evidence of a high degree of plastic deformation. Electron backscatter diffraction (EBSD) analysis shows that there is grain refinement due to plastic deformations in samples subjected to the fundamental wavelength. Microhardness distribution analysis across the subsurface region shows work-hardening effects in the laser-processed samples in the 1064 nm condition. This study also shows that there is an indication of a thermal softening effect in the samples treated with the 532 nm wavelength, and it is correlated with lower compressive residual stress across the depth.

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Effect of Laser Shock Peening without Coating on Grain Size and Residual Stress Distribution in a Microalloyed Steel Grade

Aza-donor ligands- A key to synthesizing mononuclear to coordination polymers of cadmium phosphinates.


 The failure of turbine blades due to solid particle erosion is a serious concern in aviation applications. This research investigates the solid particle erosion behaviour of laser powder bed fused IN718 alloy for the effect of temperature (400°C, 500°C and 600°C) and impact angle (45° and 90°) in a gas-jet erosion setup. The erosion rate progressively increased with the test temperature and it is significantly higher in the 45° eroded samples. The eroded samples were characterized for residual stress distribution, surface topography and surface roughness using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and 3D optical profilometer. Compressive residual stress is evident in all eroded samples, and higher residual stress is measured in the 90° eroded samples. Ploughing, crater lip formation and cracking are the erosion features observed in 45° eroded samples. In comparison, localized plastic deformation, platelet mechanisms and cracked ridges are observed in 90° eroded samples. Crack formation at 600°C test condition is attributed to severe erosion degradation in both the impact angles (45° and 90°). The as-printed and solution-double aged samples were thoroughly investigated for microstructure and microhardness distribution at the region parallel and perpendicular to the build direction.

High-Temperature Solid Particle Erosion Behaviour of Laser Powder Bed Fused Inconel 718

This paper investigates the reactivity and optical properties of transition metal-incorporated organoantimony(V) clusters prepared by a solvothermal route. The detailed structural characterization of novel heterometallic M2Sb4 oxo clusters is reported herein. Single crystal X-ray diffraction revealed the formation of hexanuclear organoantimony(V) based oxo clusters [(p-ClC6H4Sb)4V2(O)2(μ3-O)2(μ2-O)2(t-BuPO3)4(μ2-OCH3)4] (1), [M2(p-iPr-C6H4Sb)4(μ3-O)2(μ2-O)2(μ2-OCH3)4(t-BuPO3)4(py)2]·xCH3OH, where M = Mn, x = 2 (2), Co, x = 1 (3), Ni, x = 2 (4) and Cu, x = 2 (5). The magnetic behaviour of the clusters was probed by magnetic susceptibility measurements. Optical absorption studies showed that bandgap reduction can be achieved by incorporating an appropriate transition metal into the homometallic Sb6 oxo cluster.

Calvin Samuel

Papers

Effect of Laser Shock Peening without Coating on Grain Size and Residual Stress Distribution in a Microalloyed Steel Grade

Aza-donor ligands- A key to synthesizing mononuclear to coordination polymers of cadmium phosphinates.

High-Temperature Solid Particle Erosion Behaviour of Laser Powder Bed Fused Inconel 718

Tunable bandgaps in self-assembled transition metal-incorporated heterometallic M2Sb4 (M = V, Mn, Co, Ni, and Cu) oxo clusters.

Stibonic Acids / Stibonate-Phosphonate Clusters: Synthesis, Characterization and Bioactivity Evaluation