Journal of Materials Engineering and Performance最新文献

This study aims to precisely predict the onset of fracture during the single-point incremental forming (SPIF) of extra deep drawing (EDD) steel sheets using the Bao–Wierzbicki (BW) ductile damage model, incorporating anisotropy of the sheet metal in the analytical formulation. In this regard, a fresh attempt was made to optimize the theoretical BW fracture locus by optimizing the central hole (CH) fracture specimen geometry. Subsequently, four different CH specimens, namely CHD0, CHD2.5, CHD5, and CHD6, were considered by varying the hole-to-ligament width ratios within a range of 0-0.3. The CH specimen geometry was optimized by comparing the evolution of effective plastic strain with respect to stress triaxiality (left(eta right)) and the Lode angle parameter (left(theta right)). It was found that the CHD5 specimen experienced a purely uniaxial stress state with a (eta) and (theta) value almost equal to 0.33 and 1.0, respectively. Afterward, the BW damage model was calibrated using the four CH specimens, and different fracture loci were generated. Subsequently, the analytical fracture curves were validated with the safe and failed experimental strain data obtained through the SPIF of variable wall angle cone (VWAC) and variable wall angle pyramid (VWAP) cups. It was observed that the fracture locus obtained using CHD5 geometry accurately predicted the onset of fracture for SPIF cups. Further, the four distinct fracture loci were integrated separately into the finite element (FE) simulation of the SPIF process linked with the Hill48 anisotropic material model to estimate the formability. The error in dome height prediction was observed as 6.97% and 6.35% for VWAC and VWAP cups, respectively. It was concluded that the BW fracture locus calibrated using the CHD5 geometry was the optimized fracture locus. Furthermore, the surface strain distribution was predicted, incorporating the best-predicted BW fracture locus into the FE simulation. A decent agreement was observed between FE and experimental values.

In the present work, laser-powder bed fusion (L-PBF) is carried out to additively fabricate maraging steel 300 parts at different values of scan spacing (0.05 and 0.10 mm). The effect of scan space on microstructure and mechanical properties (including tensile properties and microhardness) of the as built specimens is studied. Between the two scan spacing values tested, wider scan space causes better part strength. The setting of lower scan space causes excessive energy density and consequently material loss which may possibly be due to overheating. Therefore, the part fabricated at a lower scan space corresponds to a higher level of porosity. The as built parts are then subjected to a STA (solution treatment followed by aging) schedule. Solution treatment (ST) is performed at 840 °C, 2 h + oil quenching. Afterward, the solution-annealed specimens are subjected to aging treatment (AT) at 492 °C, 2 h + oil quenching. Aging treatment promotes precipitation of secondary intermetallic phases which contribute toward imparting improved strength and hardness to the alloy. However, response of the post-heat treatment depends on the initial microstructure of the specimen (in the as built condition) as influenced by the setting of fabrication parameters. Attempt is also made to understand the effect of aging temperature (450, 490 and 550 °C) on microhardness (temperature and time for ST being constant) of the post-heat-treated specimens. It is experienced that the presence of reverted austenite lowers microhardness of the STAed specimen. The highest microhardness value (~618.2 ± 20.1 HV_0.05) is obtained upon aging at 490 °C as the corresponding specimen does not contain reverted austenite.

The pore-forming agent ammonium carbonate is used in the preparation of porous bioceramic coatings containing hydroxyapatite (HA) for bone repair via laser cladding. However, unlike certain essential bone metabolism elements, it cannot be retained in the final coating. To overcome this limitation, ceramic coatings were fabricated by incorporating varying amounts of Mg (0, 2.5, 5, 7.5, and 10 wt.%) into the coating powders prior to laser cladding, resulting in coatings label as A-0, A-2.5, A-5, A-7.5, and A-10 Mg, respectively. The influence of Mg content on the microstructure, in vitro bioactivity, electrochemical corrosion and microhardness of A-Mg coating was investigated. The ceramic coatings consisted of the phases HA, β-TCP, TiO₂, CaTiO₃, MgO, and demonstrated a metallurgical bonding between the coating and substrate. The coatings showed a partially porous structure and the introduction of Mg does not change the corrosion tendency but accelerates the corrosion rate. The lowest I_corr value 1.301 × 10^-4 A·cm^-2 for the A-0 Mg coating and highest value 3.176 × 10^-4A·cm^-2 for the A-2.5 Mg coating. Moreover, the microhardness varied with the Mg content. The maximum microhardness was 1835.6 HV_0.2 for coating without Mg, while 1360.8 HV_0.2 with Mg. In addition, all ceramic coatings exhibited a bone-like apatite formation ability in a simulated body fluid (SBF). The Mg distribution increased gradually from the deposited bone-like apatite to the dense part of the A-Mg coating as well as in regions around the pores. It can be concluded that the addition of Mg improves both the mechanical properties and in vitro bioactivity of the coating.

This study investigated the quenching-induced residual stress (RS) in the large cuboid Mg-Gd-Y-Zr-Ag alloy forging generated during manufacturing. To mitigate the detrimental effects of high RS levels, cold pressing (CP) was employed under various compression ratios. The research further systematically examined the interdependencies between RS reduction, hardness change and microstructural evolution. The results show that the RS transitioned sharply within 100 ~ 200 mm from the edge of the forging, while the directional RS was ranged from − 40 to − 65 MPa at the stress platform in the central region. It was optimal to apply a CP ratio of 1% to reduce RS, and the reduction ratio of RS on the surface layer was 77.30 ~ 97.33%. Reducing the RS by CP had barely an effect on the grain size of the forging, only the (beta^{prime }) precipitated phase during aging changed from dense and uniform distribution to uniform chain distribution, thus slightly increasing the hardness after aging.

This study investigates the effects of raster angle (0°, 45°, 90°) and infill percentage (25%, 50%, 75%, 100%) on the flexural and thermomechanical behavior of polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) parts fabricated via fused deposition modeling (FDM). A total of 24 parameter sets (12 per material) were 3D printed, with three samples per set (n = 72). Flexural testing and dynamic mechanical analysis (DMA) were conducted to assess the impact of print settings. PLA samples exhibited optimal flexural strength (167.72 MPa) at a 0° raster angle and 50% infill, while ABS achieved its highest strength (125.92 MPa) at a 0° raster angle and 75% infill. At a 90° raster angle, flexural strength decreased by over 40% for both materials, indicating significant anisotropy. DMA results revealed increased storage modulus (PLA: 3641 MPa; ABS: 2330 MPa) and loss modulus (PLA: 284 MPa; ABS: 163 MPa) at a 0° raster angle and 75% infill. Scanning electron microscopy (SEM) fractography showed brittle fracture patterns and layer separation in PLA, while ABS displayed voids and interlayer weaknesses contributing to failure. Raster orientation had a greater influence on flexural strength, whereas infill percentage more significantly affected thermomechanical behavior. These findings establish a process–structure–property framework for optimizing FDM parameters to enhance mechanical performance. The results support the development of high-performance thermoplastic components for automotive and aerospace applications and provide a foundation for extending optimization strategies to reinforced polymer composites.

Hammer peening is one of the peening technologies that use a hammer as the peening medium. Peening residual stress is the most important outcome of the peening treatment, as it determines the fatigue resistance and deformation of a component. Finite element simulation is often utilized to predict residual stress. However, numerous peening parameters and their wide range lead to a significant amount of simulation time. This paper aims to propose an algorithm to predict the peening residual stress using a small amount of simulation work. By investigating the influence of the target material models, Johnson–Cook model and Chaboche model, on the evolution of peening stress and strain, we found that the material model determines the cumulative rate of plastic deformation and the upper limit of the residual stress. Under a certain material model, the kinetic energy of the hammer is converted into plastic strain energy at a nearly constant ratio, and the plastic strain is linearly correlated with impact density. Based on these findings, a quadratic curve is introduced to represent the peening compressive stress field, and an algorithm is proposed to determine the coefficients of the curve. The predicted stress profiles agree well with the simulation values, and the simulations are verified by hammer peening experiments.

Zinc anodes degrade rapidly under high-temperature operating conditions, significantly impeding the development and commercial application of Zn–air batteries. In this study, zirconia-coated zinc (ZrO₂@Zn) was synthesized using a facile sol–gel method. The composition, structure, and electrochemical properties of the ZrO₂@Zn anode were characterized. The results show that ZrO₂@Zn has a core–shell structure contributing to regulating the cycle life of the battery. The passivation current of ZrO₂@Zn is lower than that of Zn. This indicates that ZrO₂@Zn exhibits enhanced passivation stability performance. The cycle life of ZrO₂@Zn can be extended to 72 h at extreme operating temperatures of 60 °C, nearly double that of bare Zn. The coating ZrO₂ applied on the surface of Zn can effectively avoid the direct contact between Zn and electrolyte and reduces the self-corrosion of Zn anode. The increased adsorption of H⁺ ions by ZrO₂ at elevated temperatures without affecting the deposition of Zn²⁺ prolongs the lifetime of the ZrO₂@Zn anode. The core–shell structure of ZrO₂@Zn effectively mitigates the occurrence of anodic side reactions and inhibits the growth of Zn dendrites, thereby safeguarding the active material and extending the battery’s cycle life.

In this work, the high-temperature oxidation behavior of copper-nickel-based ternary alloys with additives of refractory metals (W and Ta) was investigated using a thermogravimetric analysis. It was observed that textured tapes of studied ternary alloys have a higher oxidation resistance at the deposition temperature of functional layers, i.e., at 700 °C, compared to pure copper tapes. The chemical composition and pattern of distribution of the formed oxides were determined through electron microscopic and Raman studies of the oxidized surface of textured samples after a series of short-term annealing. The findings indicate that oxidation of the surface of (Cu + Ni)-Ta and (Cu + Ni)-W alloys initially occurs homogeneously with the formation of Cu₂O film. As a result of prolonged corrosion process, a transformation from copper (I) oxide (Cu₂O) to copper (II) oxide (CuO) undergoes in the oxide film of the investigated ternary alloys.

In this investigation, an attempt has been made to enhance the mechanical properties of modified 9Cr-1Mo steel. For this purpose, two sets of modified 9Cr-1Mo steel samples, namely Set-III and Set-IV, were prepared from hot-rolled modified 9Cr-1Mo steel. Both sets were austenitized at 1000 °C for 1 h. Then, the samples were austempered for 6 h at two isothermal temperatures, 460 °C (Set-III) and 480 °C (Set-IV), respectively, followed by water-quenching. Different fractions of bainitic/martensitic microstructure phases were observed in both cases. Subsequently, all the austempered samples were tempered at 760 °C for varying time durations. A broad range of materials characterization techniques, including XRD, SEM, TEM, and mechanical testing, were carried out. The results revealed that lower austempering temperature (460 °C) promoted a finer bainitic ferrite structure with higher dislocation density and better phase distribution, leading to improved strength–ductility balance. The size and volume fraction of precipitated carbides were found to be highly sensitive to tempering time, with a secondary hardening peak observed at 10 min due to the optimal Cr/Fe ratio in ({M}_{23}{C}_{6}) carbides. EBSD analysis showed higher low-angle boundary content in Set-III samples, contributing to better strain accommodation and toughness. Overall, the sample austempered at 460 °C and tempered for 30 min exhibited substantial improvement in ductility (13.26%), tensile toughness (10.28%), and hardness (7.50%), along with increased strength (1.38%), compared to the as-received steel. The study demonstrates that controlled bainite–martensite phase tuning and carbide evolution via optimized thermal routes can significantly enhance the mechanical performance of P91 steel.

Wire Arc Additive manufacturing (WAAM) is one of the most progressive technique used to fabricate components by depositing material in layer-by-layer sequence using inert gas welding. Aluminum–silicon alloys are commonly used in aircraft and automotive industries due to their excellent mechanical and metallurgical properties. In this work, interface metallurgical characteristics and mechanical properties of ER4043 aluminium silicon alloy deposited using WAAM process were investigated. The experimental results showed that the hardness of the deposited layers decreased with increase in the specific energy of welding. In multi-layer deposition, an increase in the hardness was observed in the previous deposited layers and at the interface zone due to reformation of large columnar grains into small grains and precipitation of more eutectic silicon content. The Scanning Electron Microscopy (SEM) images indicated that the formation of pores and delamination at the interface zone due to variation in the cooling rate during solidification and also due to formation of oxides at the interface zone. The increase in the specific energy causes formation of more oxides on the weld deposit surface due to high weld temperature results from high heat input. In Electron Back Scatter Diffraction (EBSD) analysis, the variation in crystal orientation, grain size, misorientation of grains and texture orientation were observed at the interface zone. The mechanical properties such as tensile, compressive and impact strength were observed at low level and requires post treatment process for improvement.