Journal of Materials Engineering and Performance最新文献

Enhanced formability is a key advantage of single point incremental forming (SPIF), primarily due to localized deformation and strain hardening, which improve mechanical properties. However, SPIF faces challenges under biaxial deformation due to non-uniform stress distribution. This study explores how preheating-induced textures enhance formability by stabilizing deformation. By systematically varying preheating temperatures, targeted recrystallization promotes the formation of Cube and R-Cube_ND texture components, which alter slip systems and deformation behavior. Electron backscatter diffraction (EBSD) and x-ray diffraction are used to characterize grain structures, boundary statistics, and texture evolution from the as-rolled to the preheated and formed states. Lower preheating temperatures (230 °C) favor Cube texture stabilization, while higher temperatures (330-500 °C) amplify Cube and R-CubeND components, reducing less favorable orientations like S, copper, and Goss. The reinforced Cube texture benefits from substructures that restrict deformation energy accumulation, leading to a stable texture at elevated temperatures. This texture evolution significantly impacts SPIF strain behavior, with increased presence of deformation-stabilizing Brass and P textures and improved isotropy under biaxial strain. The study demonstrates that controlled preheating enables texture manipulation, optimizing SPIF outcomes and enhancing resistance to localized failure, thus paving the way for texture-driven forming strategies in lightweight alloy applications.

The high cost of 3D printing feedstock is primarily attributed to the conversion of raw polymers into filament, which also directly impacts the mechanical, optical, and structural integrity of printed components in the fused filament fabrication (FFF) process. To address this limitation, a novel oblique (semi-vertical) filament extrusion system was developed, offering an affordable and compact solution for producing customized filaments from virgin, composite, and recycled materials. The system occupies approximately 2 m², costs between USD 600–1000, and achieves filament diameter control within ± 1.71% to ± 5.8% deviation, depending on the material. Key extrusion parameters—nozzle diameter, outlet angle, screw pulse interval, puller motor speed, and nozzle temperature—were experimentally optimized using regression modeling, with a predictive error range of 1.71-6.48% for filament diameter. Mechanical testing of 3D printed specimens confirmed strong material performance, with ultimate tensile strengths of 53.84 MPa (PLA), 29.15 MPa (TPU), and 22.18 MPa (PLA + TPU 50/50). The system also successfully processed recycled PLA and Nylon-12 powder, highlighting its material versatility and potential for circular manufacturing. Overall, this work demonstrates a scalable, low-cost, and sustainable filament fabrication method that enhances FFF capabilities for research, education, and small-scale industry.

Metal wire fusion additive manufacturing (MWFAM), an emerging metal additive manufacturing technique, has the potential to mitigate some of the drawbacks of the powder bed fusion (PBF) and fused deposition modeling (FDM) processes. MWFAM offers some advantages, such as a higher deposition rate, larger build volume and nearly fully dense metal parts with minimal porosity. In the current study, MWFAM is performed on a mild steel substrate using an in-house developed experimental setup by modifying the metal inert gas (MIG) welding setup. Detailed experimentation has been conducted to develop predictive models to evaluate the correlation between the mechanical properties of the deposited parts and the input process parameters for metal deposition. Microscopic analysis of the deposited parts is performed to examine the grains in the deposited samples and typical defects, required to optimize the process further. The mechanical characterization of the deposited specimen reveals a maximum tensile strength of around 780 MPa in the build direction. The maximum hardness of the deposited specimens is measured to be 35 HRD.

Copper foils are widely used in microelectronics and microfabrication industries due to their excellent electrical conductivity, ductility, and mechanical reliability. Multi-pass micro-rolling is an effective method to fabricate micro-/meso-scale copper products with superior mechanical performance. However, the effect of annealing temperature on grain size evolution, tensile properties, and edge crack formation of copper foils during micro-rolling remains insufficiently explored. The experimental results in this work reveal a strong correlation between annealing temperature, microstructure, and formability. The elongated grains change to recrystallized equiaxed grains, and the grain size increases as the annealing temperature increases from 300 to 700 °C. The tensile strength of annealed copper foils decreases as the annealing temperature increases from 300 to 700 °C. The elongation increases to a peak value of 25% as the annealing temperature rises from 300 to 500 °C and then decreases to 20% when the annealing temperature further increases to 700 °C. An optimal annealing temperature of 500 °C results in a refined microstructure with a weak cube texture, a large fraction of high-angle grain boundaries (HAGBs), and low dislocation density, which improves the formability and the resistance to edge cracking of copper foils. These findings contribute to a deeper understanding of the interplay between rolling parameters, microstructure, and mechanical performance of copper foils, providing valuable insights for optimizing micro-rolling processes for industrial applications.

The thermal deformation behavior and microstructural evolution of 00Ni18Co8Mo3TiAlB were systematically investigated under strain rates ranging from 0.005 to 10 s⁻¹ and temperatures between 950 and 1200 °C. A high-precision flow stress model considering strain compensation and a hot processing map of the experimental steel were established, with an analysis of microstructural evolution made. By analyzing the rheological stress–strain curves, it was found that the experimental steel exhibited dynamic recovery characteristics in the flow curve at deformation temperatures of 950-1050 °C. When the deformation temperature exceeds 1100 °C, the flow curve at a low strain rate (≤1.0 s⁻¹) exhibits the characteristics of dynamic recrystallization, which suggests that the experimental steel is more susceptible to dynamic recrystallization (DRX) under conditions of high temperature and low strain rate. Meanwhile, the thermal stability region at true strain 0.1 ~ 0.9 was obtained by building and analyzing the hot processing map, and the optimal processing windows were determined to be 1050-1130 °C/0.005-0.015 s⁻¹ and 1150-1200 °C/0.01-0.2 s⁻¹. The evolution of DRX in experimental steel was obtained through EBSD microstructure characterization, and the dominant DRX regime was confirmed. Due to the relatively high dynamic activation energy Q of the experimental steel, the recrystallization volume fraction is relatively low. Furthermore, the relationship between DRX and grain boundaries was analyzed, and it was found that the occurrence of DRX could promote the generation of large-angle grain boundaries.

Although laser cladding technique plays an important role in metal or alloy coatings at present, element segregation and uneven microstructures always exist in the laser cladding layers, which can decrease their mechanical properties and corrosion resistance. To resolve these issues, we designed a synchronous rotational magnetic field device coupled with the laser head in which a synchronous rotational magnetic field can induce Marangoni convection driven by surface tension and horizontal circulation driven by Lorentz and magnetization forces to stir the melt pool. Iron-based cladding coatings were prepared on 42CrMo substrates by changing the magnetic field strength and rotational speed, and the influence of the synchronous rotational magnetic fields on the geometric characteristics, microstructures, mechanical properties, and corrosion resistance of the cladding layer was investigated. Under the magnetic fields, the compositions of the coatings can distribute homogeneously due to the enhanced convection in the melt pools causing uniform element diffusion, and the coarse dendrites can be broken, resulting in the more uniform and dense cladding layers. These features can make the cladding layers have more excellent corrosion resistance. Correspondingly, their hardness and wear resistance can be improved. When the magnetic field strength is 20mT and the rotational speed is 64 r/min, its microhardness is up to 864.04HV_0.2, and its average friction coefficient is 0.2687. Consequently, the cladding coating with better performance can be obtained under a certain synchronous rotational magnetic field. This provides a new way for manufacturing iron-based cladding coatings with an excellent wear and corrosion resistance.

In order to investigate the effects of grain size on the mechanical properties, texture evolution, and deformation mechanisms of extruded AZ31 magnesium alloy under dynamic loading, this study uses a split Hopkinson pressure bar to perform dynamic compression at a strain rate of 1700 s⁻¹ on AZ31 magnesium alloy samples with three different grain sizes (3 μm, 35 μm, and 50 μm) along the ED direction at room temperature. The results show that with an increase in grain size, both the yield stress and peak stress of the magnesium alloy decrease. It was also found that the c-axis orientation of most grains in the samples with three different grain sizes was approximately at a 45° angle to the < 0001 > direction. When the grain size is 3 μm, the primary deformation mechanism is pyramidal < c + a > slip. For the 35 μm and 50 μm samples, the main deformation mechanisms are pyramidal < c + a > slip and {10-12} tensile twinning, and as the grain size increases, the activity of {10-12} tensile twinning increases. As grain size increases, the rising proportion of {10-12} tensile twinning activity suppresses the activation of pyramidal < c + a > slip, thereby reducing the ductility of the magnesium alloy.

Eutectic high-entropy alloy (EHEA) combines the advantages of eutectic alloys and high-entropy alloys, which display good tensile properties and castability. However, due to the high content of hard phases and significant mismatch, more EHEA systems exhibit shortcomings such as early fracture and poor machining ability. Thus, it is a key that adjusts the element ratio and phase ratio to improve the mechanical property of EHEAs. In this work, Al₉Cr₁₂Fe₂₀V₁₂Ni₄₇ EHEA reveals ultimate tensile strength and yield strength of 1403 ± 50 MPa and 947 ± 20 MPa, respectively. Meanwhile, Al₉Cr₁₂Fe₂₀V₁₂Ni₄₇ also maintained an elongation rate of nearly 20 ± 3%. The excellent strength and ductility of the Al₉Cr₁₂Fe₂₀V₁₂Ni₄₇ were mainly ascribed to combine soft FCC phase and hard acicular structure, indicating a significant hetero-deformation-induced (HDI) strengthening. This work opens up new possibilities for realizing high-strength and ductile metal parts with complex shapes by designing special eutectic weaving structures.

The microstructure evolution and mechanical properties of 15-5PH stainless steel were investigated under different aging temperatures and holding times. The phase formation and growth mechanisms were studied by microstructure analysis, and the mechanical properties were investigated using tensile and impact tests. The results show that NbC and MoC particles are precipitated between the martensite laths after aging, which grow larger with increasing aging time and temperature. When the aging temperature is increased to 550 °C and 580 °C, ε-Cu phases appear and distribute homogeneously in the matrix. The hardness and tensile strength of the 15-5PH decrease with increasing aging temperature, while the elongation is improved. The samples after aging at 550 °C and 580 °C possess excellent impact toughness of 225 and 223 J/cm². The reverse transformation of martensite to austenite occurs during high-temperature aging, reducing the strength and hardness of the samples, while improving its impact toughness. However, high aging temperature leads to coarsening of NbC, MoC, and ε-Cu, resulting in a simultaneous decrease in strength and fracture toughness. The present results contribute to the practical application of high-performance 15-5PH alloys and provide a reference for the processing of other age-strengthened stainless steels.

To systematically investigate the effects of ultrasonic surface rolling process (USRP) on the surface integrity and fatigue properties of 20CrNiMo carburised steel, a three-dimensional model of USRP was constructed based on a combination of finite element simulation and experimental validation, revealing the mechanism of ultrasonic amplitude, static load and other parameters on the distribution of residual stresses and plastic deformation behaviour. The results show that the residual compressive stress value of the surface layer increases with the optimization of processing parameters due to the USRP treatment, and the maximum residual compressive stress is located on the subsurface, and the simulation and experimental errors of multi-pass processing are controlled within 5%, which verifies the reliability of the model. Through the orthogonal experimental design combined with grey correlation analysis and principal component analysis, the optimized parameter combinations were obtained: static load of 1400 N, ultrasonic amplitude of 6 μm, rolling passes: 6, and step distance of 0.05 mm. Under these parameters, the surface microhardness was increased by 8.7% to 751.3 HV_0.5, roughness was reduced by 34% to 0.29 μm, grain size was refined by 11% to 0.81 μm, the ratio of small. The proportion of angular grain boundaries increased, and the KAM value increased from 1.60° to 1.99°, indicating a significant increase in dislocation density. USRP did not change the phase composition of the material, but the martensitic microstructure was converged through intense plastic deformation, forming a gradient nanostructure. Corrosion resistance tests showed that the corrosion potential was positively shifted and the corrosion tendency was reduced after USRP treatment. Rotational bending fatigue experiments show that the median fatigue life of the specimen with optimal parameters reaches 18,503 cycles, which is 268% higher than the original specimen. The fatigue crack source is shifted from the surface to the subsurface layer, which is attributed to the synergistic effect of the reduction of surface roughness, the introduction of residual compressive stresses and grain refinement. The study confirms that at a static load of 1000 N, the improved corrosion resistance effect of surface quality enhancement counteracts the negative impact of increased geometric dislocation density.