The residual stress field induced by surface strengthening processes such as mechanical shot peening and other forms of plastic deformation does not generally exhibit a simple"monotonic"distribution *** rese...
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The residual stress field induced by surface strengthening processes such as mechanical shot peening and other forms of plastic deformation does not generally exhibit a simple"monotonic"distribution *** researchers have analyzed this fact from a mechanical perspective based on Hertz ***,the micro/nano-scale microstructural changes corresponding to the distribution of residual stress fields still appear to be *** this study,we focused on a widely used material in aviation manufacturing,namely nickel-based superalloy GH4169,as our experimental *** subjected GH4169 alloy to me-chanical strengthening treatment using a shot peening intensity of 0.25 mmA,followed by quantitative testing of micromechanical performance indicators such as microhardness and residual *** thor-oughly investigate the relationship between micromechanical properties and microstructure changes,we utilized transmission electron microscopy(TEM)to observe and analyze shot-peened materials at differ-ent *** findings revealed that the most severe microstructural distortion induced by mechanical shot peening in GH4169 alloy was likely to occur within a depth range of 25 to 75 *** observation aligns with the actual phenomenon that the maximum microhardness and maximum residual compres-sive stress did not manifest on the outermost surface of the *** presenting a detailed analysis of deformation defects such as dislocations,stacking faults,and twinning in different depths of mechan-ically strengthened layers,our study contributes to a deeper understanding and practical application of post-processing technologies based on plastic deformation.
The problems of electromagnetic wave(EMW)pollution in X and Ku bands(8–18 GHz)are becoming more and more ***,it is urgent to design EMW absorbing materials with high-efficiency such as thin thickness,lightweight,wide...
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The problems of electromagnetic wave(EMW)pollution in X and Ku bands(8–18 GHz)are becoming more and more ***,it is urgent to design EMW absorbing materials with high-efficiency such as thin thickness,lightweight,wide bandwidth and strong EMW *** by the biomorph of sea cucumber,Nb_(2)CT_(x) MXene@Co nitrogen-doped carbon nanosheet arrays@carbon fiber aerogels(Nb_(2)CT_(x)@Co-NC@CFA,Nb_(2)CT_(x)=niobium carbide)were constructed by self-assembly,in-situ chemical deposition and subsequent *** carbon fiber aerogel,as the basic skeleton of sea cucumber,forms lightweight three-dimensional interconnected conductive network,enhances the dielectric loss and extends the multiple reflection and absorption paths of *** the tentacles of sea cucumber surface,Nb_(2)CT_(x) MXene and Co nitrogen-doped carbon nanosheet arrays exist rich heterogeneous interfaces,which play an important role in improving EMW polarization loss and optimizing impedance *** minimum reflection loss(RLmin)of Nb_(2)CT_(x)@Co-NC@CFA reaches−54.7 dB at 9.84 GHz(2.36 mm)with a low filling ratio of 10 wt.%and the effective absorption bandwidth(EAB)of Nb_(2)CT_(x)@Co-NC@CFA reaches 2.96 GHz(8.48–11.44 GHz)with 2.36 mm and 5.2 GHz(12.8–18 GHz)with 1.6 mm,covering most of X and Ku bands by adjusting *** radar cross section(RCS)value of Nb_(2)CT_(x)@Co-NC@CFA is 26.64 dB·m^(2),which is lower than that of the perfect electrical conductor(PEC),indicating that Nb_(2)CT_(x)@Co-NC@CFA can effectively decrease the probability of the target being detected by the radar *** work provides ideas for design and development of EMW absorbing materials with high-efficiency EMW absorption in X and Ku bands.
To mitigate the substantial computational costs associated with modeling the mechanical behavior of large-scale architected lattice structures, this work introduces a concurrent multiscale approach: the Generalized No...
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The study focuses on a novel post-treatment method, high-energy impact composite modification, combining mechanical shot peening and laser shock processing to improve the fatigue performance of the nickel-based supera...
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The study focuses on a novel post-treatment method, high-energy impact composite modification, combining mechanical shot peening and laser shock processing to improve the fatigue performance of the nickel-based superalloy GH4169 at intermediate temperatures. The synergistic interaction between mechanical impact (SP-induced plastic deformation) and laser-induced shock waves enabled a 2.5-fold increase in effective treatment depth (up to 1500 μm) compared to SP alone (400 μm), while achieving a surface hardness of 520 HV and compressive residual stress of −1465 MPa, exceeding single-process results by 4.5% and 54.2%, respectively. The dual-impact approach significantly enhanced surface hardness and compressive residual stress, addressing the high sensitivity to stress concentration. Experimental results demonstrate that HEICM eliminated stress concentration sensitivity at 650 °C, elevating the fatigue limit of notched specimens (Kt = 3) to 638 MPa – equivalent to the fatigue strength of smooth specimens (Kt = 1) in conventional grinding states (636 MPa). This represents a 116% improvement over untreated notched specimens (295 MPa) and surpasses SP-treated counterparts (446 MPa) by 43%, thereby extending the fatigue life of GH4169 alloys in aerospace applications.
Thermal barrier coatings (TBCs) were deposited on DD6 specimens with [001] orientation, and the TBCs coated DD6 specimens were exposed at 1150 °C for one hour. Then, both the TBCs coated and bared specimens were ...
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Despite the advancements of traditional surface treatments like shot peening (SP) and laser shock peening (LSP) in enhancing the fatigue life of GH4169 superalloy, these techniques remain limited, particularly under h...
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Despite the advancements of traditional surface treatments like shot peening (SP) and laser shock peening (LSP) in enhancing the fatigue life of GH4169 superalloy, these techniques remain limited, particularly under high-stress concentration conditions. This study introduces a novel high-energy impact composite modification method that integrates SP and LSP to comprehensively address the fatigue strength sensitivity to stress concentration, a persistent issue for GH4169 in high-cycle fatigue applications. For the modified specimens, the fatigue limit under high-stress concentration conditions of Kt = 3 increased from 215 MPa to 517 MPa, more than doubling. Compared to grinding, composite modification shifts fatigue crack initiation from the surface to subsurface regions, demonstrating superior fatigue resistance. The high-intensity surface modification eliminates structural stress concentration as the primary factor determining the fatigue life of the material. The concentrated stress at the carbide phase interfaces within the material, which cannot be sufficiently weakened by residual compressive stress, becomes the new weak point. The study concludes that high-energy impact composite modification offers a viable method to enhance the durability and performance of GH4169 superalloys in demanding applications.
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