Search Results (253)

This study investigated the correlation between mechanical strengthening and electrochemical corrosion behavior in 18Ni300 maraging steel fabricated via laser powder bed fusion (LPBF). To evaluate the impact of post-processing, specimens were analyzed under four conditions: solution treated (S), solution peened (SP), solution aged (SA), and solution aged peened (SAP). The aging treatment (490 °C for 6 h) effectively enhanced the corrosion resistance by homogenizing the martensitic matrix and promoting the formation of a stable passive film, resulting in the lowest corrosion current density (<!-- MathType@Translator@5@5@MathML2 (no namespace).tdl@MathML 2.0 (no namespace)@ --> Full article

Peen forming is a dieless manufacturing process used to shape large, thin aerospace panels through controlled shot impacts that induce residual stresses and curvature. Despite long-standing industrial use, process monitoring still depends largely on indirect proxies such as Almen intensity and coverage, limiting spatially resolved deformation assessment and hindering closed-loop control. In parallel, vision-based artificial intelligence (AI) has enabled adaptive monitoring and feedback in smart-manufacturing domains such as welding, additive manufacturing, and sheet forming. This review examines how such sensing and learning strategies can be transferred to adaptive peening forming. We compare six vision sensing modalities and assess major AI model families for surface mapping, temporal prediction, robustness, and deployment maturity. The synthesis shows that progress is primarily constrained by limited validated datasets, harsh in-cabinet sensing conditions, scarce closed-loop demonstrations, and weak validation on curved aerospace geometries. We conclude that the sensing and AI foundations for adaptive peen forming are already emerging, but industrial translation now depends on stronger experimental validation, standardized benchmarking, robust multi-sensor integration, and edge-capable feedback pipelines. Full article

Titanium alloys exhibit exceptional strength-to-density ratios, high hardness, and outstanding resistance to elevated temperatures, making them indispensable structural materials in aerospace engineering, marine construction, and biomedical applications. In aerospace systems specifically, fatigue failure represents the predominant failure mode for titanium alloy components. This review systematically examines prevalent surface treatment techniques for titanium alloys—including shot peening, ultrasonic rolling treatment, hot isostatic pressing (HIP), physical vapor deposition (PVD), micro-arc oxidation (MAO), and thermal spray processes—and critically evaluates their respective effects on fatigue performance. The underlying mechanisms of each technique are concisely outlined, with emphasis on stress state evolution, near-surface microstructural refinement, and interfacial integrity. Building upon the characteristic surface-dominated fatigue fracture behavior of titanium alloys, this work focuses on how coating composition, architecture (e.g., graded, multilayer, or nanocomposite designs), and interfacial bonding strength govern fatigue resistance. A unified analysis is presented on the distinct yet complementary roles of substrate deformation strengthening (e.g., residual compression, grain refinement) and coating-mediated protection (e.g., barrier function, crack deflection, stress redistribution) during fatigue crack initiation and propagation. Key determinants of fatigue performance, including residual stress distribution, coating/substrate adhesion, thermal mismatch, and environmental degradation susceptibility, are rigorously assessed. Finally, emerging research frontiers are identified, including intelligent process–structure–property mapping, in situ monitoring of fatigue damage at coated interfaces, and design of multifunctional gradient coatings that synergistically enhance strength, wear resistance, and fatigue endurance of titanium alloy components. Full article

Additive-manufactured (AM) 316L stainless steel, produced via direct metal laser sintering (DMLS) and characterised by a surface topography of high irregularities and tensile residual stresses with specific anisotropy, was subjected to milling and shot peening. The milling process caused a reduction in surface topography parameters, but tensile residual stresses increased significantly. The shot peening process was carried out according to the full factorial design 3² and technological parameters such as a shot diameter in the range of 1-3 mm and an air supply pressure between 0.2 and 0.6 MPa. As a result of the experiments and the analysis, reduced surface topography was achieved, and a favourable residual stress state was formed with compressive stresses. The mechanism of the changes was demonstrated via microstructure observation and statistical models obtained by mathematical analysis. Full article

Shot-peening treatments improve the fatigue performance of mechanical components thanks to the surface modifications introduced and mainly due to the residual compressive stresses present in the layer of material near the shot-peened surface. There is no unanimous agreement in scientific literature regarding the kinetics of the damage process. However, it is generally accepted that, due to morphological and microstructural changes in the shot-peened layer, the material is more prone to early crack initiation, the propagation of which is then significantly slowed down or even stopped by the local stress field. This work focuses on applying the acoustic emission (AE) technique to detect fatigue crack initiation and propagation in shot-peened Al-alloy components. The analysis is conducted on Al-7075-T6 alloy, subjected to different shot-peening conditions and fatigue tested under alternating four-point bending. The results from the AE analyses are then correlated with a fractographic analysis. For all shot-peening conditions investigated, acoustic emission consistently indicated probable crack nucleation at approximately two-thirds of the total fatigue life, followed by a significant damage accumulation phase prior to dominant crack propagation. The final increase in acoustic activity coincided with the measurable loss of stiffness, confirming the onset of accelerated crack growth leading to fracture. The results demonstrate that, despite some experimental challenges, AE monitoring has the potential for the early detection of damage initiation. Full article

Fatigue properties remain a key challenge for aluminum–steel self-piercing riveted (SPR) joints in lightweight structures. This study evaluates shot peening as a pretreatment for the AA5052 sheet to improve the fatigue behavior of AA5052/SPFC440 dissimilar joints and to clarify the underlying mechanisms. Shot-peened and conventional SPR joints were prepared for comparison. Quasi-static tensile tests were conducted, and tension–tension fatigue tests were performed at high and low load levels. After shot peening, multiple factors with residual compressive stress, subsurface hardening, and surface roughness influenced the fatigue performance of the SPR joints. This led to a load-level-dependent fatigue behavior, with improved fatigue performance at low load levels and reduced performance at high load levels. At high load conditions, the increased surface roughness played a more significant role, with more crack initiation sites observed, resulting in fatigue lives comparable to or slightly lower than those of conventional joints. In contrast, at low load levels in the long-life regime, surface tensile stress was effectively reduced, crack initiation at surface defects was suppressed, and crack initiation shifted from the surface to subsurface regions, resulting in an 11.3% improvement in fatigue strength. These findings provide practical guidance for improving the fatigue performance of dissimilar-material SPR joints through material surface pretreatment. Full article

This paper focuses on analyzing the corrosion mechanism of stone cutting tool surfaces. Rare earth oxide films were prepared on the tool surface using the electrophoretic deposition–sintering method, and their corrosion resistance was investigated. Microstructural and compositional analyses of the surface layer of shot-peened tools and rare earth oxide films were conducted using characterization techniques such as SEM, EBSD, and XRD. The corrosion resistance of the rare earth oxide films was evaluated via an electrochemical workstation. The results indicate that the corrosion morphology on the stone cutting tool surface is pitting corrosion, which is significantly influenced by the friction of the tool coolant. Shot-peening treatment refines the grains in the tool surface layer, promoting the growth of rare earth oxide films. The rare earth oxide film is mainly composed of cerium oxide (CeO₂), presenting a continuous and dense structure with slight peeling after sintering. The Group 3 (0.1 mol/L, 3000 V/m, 5 min) rare earth oxide film exhibits the optimal electrochemical behavior and excellent corrosion resistance, with a corrosion potential (Ecorr) of −0.49 V and a corrosion current density (icorr) of 1.445 × 10⁻⁷ A/cm². Full article

Gear systems operate under high mechanical and tribological loads, making their surfaces vulnerable to wear and fatigue. Improving surface durability requires finishing processes that improve near-surface properties and extend service life. Since machine hammer peening (MHP) offers such potential, this study investigates its influence on the performance of case-hardened spur gears and evaluates its suitability as an alternative to shot peening as a conventional finishing method. Analog specimens with simplified geometries were treated using various MHP parameters to identify effective process settings. These optimized settings were then applied to real spur gears to assess performance under practical conditions. The experiments showed that MHP can significantly modify surface integrity, achieving surface roughness reductions of up to 55%, surface hardness increases of up to 30%, and compressive residual stresses exceeding −1400 MPa with stability to depths of 200 µm. These modifications resulted in improved wear and fatigue performance, with increases in load cycle number in the tooth flank up to 99% and an increase in load amplitude in the tooth root of more than 5%. For comparison, specimens were also treated with shot peening. Although MHP induced stronger surface integrity modifications, shot peening achieved higher overall load-carrying capacity because several critical areas could not be fully accessed by MHP, limiting its effectiveness. Overall, MHP shows promise as a finishing process, but its full potential depends on overcoming accessibility limitations in complex gear geometries. Full article

The present work aims to develop a deformation-based method for measuring the residual stress of the strengthened layer. The proposed method determines both the average residual stress in the strengthened layer and the layer’s thickness from the change in surface curvature after partial substrate removal. In order to examine the feasibility of the proposed method, the residual stress in the surface-strengthened layers and the layers’ thickness of 45 and 16Mn steel specimens subjected to shot-peening are measured using the proposed method and the widely recognized X-ray–electrochemical corrosion stripping method (X-/ECSM). The maximum differences in the residual stress and the thickness between the two methods for the two specimens are 19.7% and 17.6%, respectively. The results of two methods still show acceptable agreement, supporting the feasibility of the proposed method. The newly proposed method offers simpler specimen preparation, better machining accuracy control, and a more streamlined procedure compared to classical methods. However, it is inherently destructive, cannot determine residual stress distribution, and is unsuitable for specimens with complex geometries. Full article

To address surface defects and enhance the wear resistance of 316L stainless steel parts fabricated by Selective Laser Melting (SLM), this study applied shot peening (SP) surface treatment to the SLM-processed samples. Ball-on-disk tribological tests were systematically conducted under water-lubricated conditions to investigate the evolution of surface morphology, microstructure, microhardness, and tribological performance before and after SP. The results indicate that SP induced severe plastic deformation in the surface layer, effectively refining the coarse columnar crystals and melt pool structures characteristic of SLM, and forming a crystalline hardened layer with a depth of 70–80 μm. Consequently, the surface microhardness increased by 21.97% compared to the un-peened samples. Under loads of 20 N and 30 N, the coefficient of friction (COF) of the SP-treated samples decreased by 16.36% and 12.4%, while the wear rate was reduced by 17.09% and 14.9%, respectively. In this load range, the samples primarily exhibited uniform plowing and localized adhesive wear, demonstrating significantly improved resistance to plastic deformation and crack initiation. However, when the load increased to 40 N, intense stress and thermal effects diminished the strengthening benefits of SP, resulting in no significant difference in tribological performance between the SP-treated and untreated samples. At this stage, the dominant wear mechanism transitioned to severe plastic deformation, extensive delamination, and thermally induced adhesion. Full article

Cr8 steel should be Steel containing ~8 wt.% of chromium is widely used in demanding die applications due to its excellent wear resistance; however, conventional shot peening, while enhancing strength, inevitably increases surface roughness, thereby compromising overall performance. To address this limitation, this study systematically investigates the influence of ultrasonic surface rolling (USR) step size—comparing 0.06 mm and 0.12 mm—on mitigating surface degradation and improving surface integrity. Friction wear and electrochemical corrosion tests demonstrate that USR effectively reduces surface roughness and enhances microhardness. The 0.06 mm step size achieves superior results, yielding the lowest surface roughness (0.8317 μm), highest microhardness (647.47 HV), lowest friction coefficient (0.655), and optimal corrosion resistance (minimum corrosion rate reduction: 3.472 µA·cm⁻², corresponding to an inhibition efficiency of 37.05%). These performance improvements are attributed to the synergistic effects of surface smoothing and work hardening, resulting from more uniform processing achieved under a smaller step size. Consequently, a 0.06 mm step size is determined to be optimal, establishing the integrated shot peening–USR process as a highly effective strategy for enhancing surface properties and extending the service life of critical Cr8 steel components in industrial applications. Full article

Shot peening is a widely used surface treatment method for improving fatigue life by inducing surface compressive residual stresses. In critical automotive components such as parabolic leaf springs, shot peening under pre-tension (stress shot peening) can further enhance durability. This study presents a finite element model simulating stress peening in high-strength spring steels, incorporating realistic boundary conditions, material degradation due to decarburization, and stochastic shot properties, offering a high-accuracy yet computationally efficient alternative to extensive experimental testing. Results show that both below- and above-yield pre-stressing produce beneficial residual stresses, while the consideration on decarburization effects significantly alters surface stress fields. The model offers a reliable, time-efficient alternative to experiments for process and fatigue life optimization. Full article

This work presents a dynamic flowsheet model that predicts residual stress from shot peening. The peening medium is characterized by size and shape, and evolves dynamically with abrasion, fracture, classification, and replenishment. Because particle size and impact location vary stochastically, the resulting residual stress field is spatially heterogeneous. Residual stress fields are predicted in real time through a convolutional long short-term memory (ConvLSTM) neural network trained on finite element simulations, enabling fast, mechanistically grounded prediction of surface stress evolution under industrial shot peening conditions. We deploy the model in a pair of 10,000-cycle production peening case studies, demonstrating that media recharge strategy has a measurable effect on residual stress outcomes. Full article

This study investigates the fatigue life of heat-treated and shot-peened antiroll bars used in heavy-duty truck suspensions. These components enhance vehicle stability by increasing torsional stiffness. Experimental tests, including microstructure inspection, hardness, and roughness measurements, assess material properties and manufacturing effects such as decarburization and shot peening. Subjected to multiaxial proportional loading, the bars present complex fatigue behavior. The study focuses on fatigue life influencing factors and the determination of S-N curves for the fatigue-based design of full-scale components. Full article

Aluminum alloys require improved surface performance to satisfy the demands of today’s aerospace, automotive, marine, and structural applications. This paper compares three key surface hardening methods: diffusion-assisted microalloying, thermomechanical deformation-based treatments, and composite/hybrid reinforcing procedures. Diffusion-assisted Zn/Mg enrichment allows for localized precipitation hardening but is limited by the native Al₂O₃ barrier, slow solute mobility, alloy-dependent solubility, and shallow hardened depths. In contrast, thermomechanical techniques such as shot peening, surface mechanical attrition treatment (SMAT), and laser shock peening produce ultrafine/nanocrystalline layers, high dislocation densities, and deep compressive residual stresses, allowing for predictable increases in hardness, fatigue resistance, and corrosion performance. Composite and hybrid reinforcement systems, such as SiC, B₄C, graphene, and graphite-based aluminum matrix composites (AMCs), use load transfer, Orowan looping, interfacial strengthening, and solid lubrication effects to enhance wear resistance and through-thickness strengthening. Comparative evaluations show that, while diffusion-assisted procedures are still labor-intensive and solute-sensitive, thermomechanical treatments are more industrially established and scalable. Composite and hybrid systems provide the best tribological and load-bearing performance but necessitate more sophisticated processing approaches. Recent corrosion studies show that interfacial chemistry, precipitate distribution, and galvanic coupling all have a significant impact on pitting and stress corrosion cracking (SCC). These findings highlight the importance of treating corrosion as a fundamental design variable in all surface hardening techniques. This work uses unified tables and drawings to provide a thorough examination of strengthening mechanisms, corrosion and fatigue behavior, hardening depth, alloy suitability, and industrial feasibility. Future research focuses on overcoming diffusion barriers, establishing next-generation gradient topologies and hybrid processing approaches, improving strength ductility corrosion trade-offs, and utilizing machine-learning-guided alloy design. This research presents the first comprehensive framework for selecting multifunctional aluminum surfaces in demanding aerospace, automotive, and marine applications by seeing composite reinforcements as supplements rather than strict alternatives to diffusion-assisted and thermomechanical approaches. Full article