Journal of Materials Engineering and Performance最新文献

In this study, Cu-10Pb-10Sn/steel bimetallic samples were prepared using the solid-liquid composite method for Cu-10Pb-10Sn alloy. The friction and wear behavior of Cu-10Pb-10Sn alloy and GCr15 stainless-steel rings under various loads, sliding speeds, and lubrication media were systematically investigated using a ring-block friction testing device. Experiments were conducted under dry friction, kerosene lubrication, and oil lubrication conditions, focusing on the coefficient of friction, wear volume, wear rate, abrasive wear morphology, and wear surface characteristics. The wear mechanism of the Cu-10Pb-10Sn alloy under the different conditions was also analyzed. The results demonstrate that, under three working conditions—dry friction, kerosene lubrication, and oil lubrication—the wear rate and wear volume of the alloy vary differently with changes in load and rotational speed. Additionally, the friction mechanism evolves differently under each of these conditions. Under dry friction conditions, wear severity is reduced at high speeds. Under kerosene lubrication, the wear behavior is comparable at high speeds and high loads. Oil lubrication is more suitable for high-speed conditions. The combined multi-case tribological performance of Cu-10Pb-10Sn alloys demonstrates the best tribological performance under oil lubrication. This study provides a theoretical basis for the selection of lubricants and the optimization of lubrication conditions. Additionally, it provides practical guidance for the design and operation of piston pump components, while also advancing the development of lubrication technology in the field of tribology.

This study aimed to investigate the synergistic effect of laser texturing and superhydrophobic coatings on lubrication and tribological properties. To this end, superhydrophobic Ni coatings with micro-nanocomposite structures were prepared on copper substrates using a laser etching-electrodeposition combination process. The frictional behavior of the superhydrophobic planar texture was examined in the context of dry grinding, depleted oil and rich oil conditions. Furthermore, the frictional behavior of the gradient texture was investigated at varying rotational speeds. The findings suggest that superhydrophobicity has a considerable impact on lubrication and friction reduction in the context of rich oil conditions. In comparison with oleophilic surfaces, the average coefficient of friction is reduced by approximately 20%. Furthermore, superhydrophobic surfaces can transition to mixed lubrication and dynamic pressure lubrication states more rapidly than hydrophilic surfaces when presented with gradient textures. In the case of composite textures, grooves can facilitate the delivery of lubricating fluid while simultaneously reducing the dynamic pressure of microfluidics and enhancing the bearing capacity of the oil film. Finally, the frictional lubrication mechanism of superhydrophobic surfaces under diverse operational conditions was meticulously delineated. This research offers valuable insights into the intricate relationship between surface texture and the underlying friction lubrication mechanism.

This paper investigated the ballistic impact behavior of high-strength bimodal Ti-5553 alloy armor against a 7.62 mm armor-piercing incendiary projectile. The V₅₀ limit velocity of the armor is high as 415 m/s, which is much higher than that of titanium alloy armors that are fabricated by coarse-grain Beta titanium alloy or bimodal Ti-6Al-4V titanium alloy. The penetration mechanism of the armor is the pure plugging, and the plugging leads to the formation of the thin adiabatic shear band (ASB) on the penetration channel of the armor. Compared with the initial bimodal microstructure consisting of the rodlike primary Alpha phase and the equiaxial prior Beta grain, the microstructure within the ASB evolves drastically. First, the rodlike primary Alpha phase transforms into Alpha fiber with the diameter of 200 nm. Second, with the intragranular Alpha (Alpha_Intra) → Beta transformation and the dynamic recrystallization of the transformed Beta phase, the equiaxial prior Beta grain disappears. Here, we attribute to excellent ballistic performance of the bimodal Ti-5553 to the higher dynamic strength, high critical strain for ASB formation, and microstructural evolution during failure/plugging along the ASB. In addition, the ultra-high dynamic strength of the armor could result in the blunting of the steel core during the penetration, which is also beneficial to the ballistic performance of the armor.

The present study focuses on producing an interface at micro- and nano-level on complex curved and plane features of Ti-6Al-4V (α + β) alloy through wire electric discharge machining (WEDM) which simultaneously does machining and surface modification. The process parameters such as servo voltage, pulse on-time, pulse off-time and wire speed are used as input controls to comprehend the surface attributes of complex curved features at different scales. A thorough statistical, parametric, surface integrity, modified layer, layer hardening, surface porosity and surface spectroscopical analyses are carried out for a comprehensive evaluation of surface properties. Multi-attribute optimization resulted in optimized process settings S_V (70 V), P_off (40 μs), P_on (8 μs) and W_S (6 mm/s) achieving 75.51% combined desirability of both responses. The predicted and experimental results are validated under a 95% confidence interval showing less than 5% error. The optimized parametric conditions show 3.58 μm surface roughness on curved features and 3.27 μm on plane features.

AlCoCrFeNiMo_x high-entropy alloys (HEA) coating was conducted on the surface of 45-steel substrates using high-speed laser cladding (HSLC) technology. This study investigated the influence of molybdenum (Mo) on the phase structure, microstructure, and properties of the coating. The results show that the coating has a small heat-affected zone and strong metallurgical bonding with the substrate. The AlCoCrFeNiMo_x HEA coating is composed of a single body-centered cubic (BCC) phase structure. The microstructure of the coating comprised columnar crystals and Mo refined the microstructure, changing from coarse to slender columnar crystals with increasing Mo content. When x = 0.8, the hardness of the coating is the highest, up to 860 HV, and the self-corrosion current density of the coating is the smallest, about 5.7452 × 10⁻⁷ A cm⁻². The inclusion of Mo increases the coating’s oxidation resistance at high temperatures. The structural integrity of the coating may still be preserved after oxidation at 1200 °C for 90 h. When x = 0.8 to 1.0, the coating has a reduced oxidation rate, and the oxidation process follows the growth kinetics curve, and Al₂O₃ and Cr₂O₃ are the predominant oxides on the surface.

This work examines the wear and tensile behavior of additive manufactured maraging steel, fabricated through the selective laser melting (SLM) technique. Distinct SLM process parameters were selected for the production of maraging steel, including laser power, scan speed, layer thickness, and hatch distance to determine their influence on wear and tensile performance. The results showed that higher laser power improved material fusion, enhancing wear resistance up to an optimal point, beyond which excessive power led to defects like cracks, increasing wear. Similarly, scan speed and layer thickness significantly influenced the material’s microstructure, with lower speeds and thinner layers providing better bonding and reduced porosity. Increased load and sliding distance led to higher wear rates due to intensified plastic deformation and abrasive wear mechanisms. Laser power of 270 W resulted in the highest tensile strength of 1156.67 MPa due to improved layer bonding. SEM analysis of the worn surfaces revealed the presence of abrasive grooves, delamination, and third-body wear debris contributing to material degradation.

The aim is to investigate the cutting machining mechanism of FeCoCrNiAl high-entropy alloy after severe plastic deformation enhancement. The effects of factors such as rolling reduction on the cutting temperature, cutting force, and residual stress of FeCoCrNiAl high-entropy alloy were analyzed using the finite element method, and related verifications were conducted through experiments. The results indicate that an increase in cutting speed and cutting depth leads to a rise in cutting temperature, while an increase in reduction amount results in a decrease in cutting temperature. When the reduction amount is 1 mm, an increase in cutting depth from 0.5 to 1 mm leads to an approximately 192 °C increase in temperature; the increase in cutting speed and cutting depth causes the cutting force to rise, with the cutting depth having a more significant impact on the cutting force. With a rolling reduction of 3 mm and an increase in cutting depth from 0.5 to 1 mm, the cutting force approximately doubles, and there is a negative correlation between cutting force and reduction amount. The residual compressive stress on the processed surface shows a significant negative correlation with cutting speed, while there is a significant positive correlation between cutting depth and residual compressive stress; the influence of rolling reduction on the residual compressive stress of the machined workpiece is mainly reflected in the depth of the residual stress layer.

Aluminum-forming austenitic stainless (AFA) steel is a kind of promising cladding material for advanced nuclear energy systems. To further improve its high-temperature strength and irradiation resistance, a new type of oxide dispersion strengthened (ODS) AFA steel was prepared by mechanical alloying (MA), hot isostatic pressing (HIP), and forging, followed by aging at different conditions. The microstructure and mechanical properties of the ODS-AFA steel were systematically characterized using transmission electron microscopy (TEM) equipped with an energy dispersive spectroscopy (EDS) and electronic universal testing equipment. The effect of aging conditions on the microstructure and mechanical properties of the ODS-AFA steel was investigated. The composition of the dispersed oxide particles in the sample is Y₄Zr₃O₁₂, and its number density is 10²¹-10²³ m⁻³. These oxide dispersoids are quite stable after high-temperature aging. The tensile properties of ODS-AFA steel are significantly better than those of traditional AFA steels due to the dispersion strengthening effect of oxide particles. Substantial precipitation of B2-NiAl and Laves phases occurs at 700 °C, which results in a further increase in yield and tensile strength. The sample obtained the best strength-ductility matching aged at 700 °C for 120 h. Its tensile strength was 1012.94 MPa with a high elongation of 31.5%.

Clad plates are favored by many companies and experts for their superior comprehensive performance. The traditional composite process takes the rolled sheet as a starting point; the deformation energy and deformation time are insufficient due to the limitation of the rolling pass. Thus, the bonding strength is not ideal, and the microstructure property gradient is large. The new generation thermomechanical control process (NG-TMCP) can regulate the properties of the plate. Based on this, a short rolling process is introduced by moving forward the rolling composite starting point, which produces high-performance clad plates from low-performance cast billets. In this paper, the NM400/Q345 clad plates were fabricated by short rolling. The properties and microstructure were investigated at reduction ratios of 45%, 60%, and 70%. Results show that the tensile strength and elongation after fracture are not inferior to the Q345 and NM400 of the same specification. The bonding strength increased with the increase of the reduction ratio. The interface becomes clearer and flatter. The elongation after fracture increased first but then decreased. Fine equiaxed grains obtained by recrystallization are elongated along the rolling direction at the reduction ratio of 70%. Interfacial oxide is broken into fine particles and distributed evenly.

This study investigates the influence of various heat treatment processes on the dynamic impact properties of 7075 aluminum alloy. Dynamic compression tests were performed using a Hopkinson pressure bar over a temperature range of 20 °C to 420 °C and strain rates from 1800 to 5800 s⁻¹, followed by an analysis of the alloy’s mechanical behavior under these conditions. The findings show that the yield strength of 7075 aluminum alloy, after undergoing three distinct heat treatment procedures, increases with higher strain rates and decreases as temperature rises, indicating a clear sensitivity to both factors. At ambient temperature, the flow stress of the alloy demonstrates an upward trend across all three heat treatments as the strain rate increases. Specifically, the yield strengths in the T6, T76, and RRA conditions at a strain rate of 5800 s⁻¹ are 1.47, 1.38, and 1.19 times greater than those measured at 1800 s⁻¹, respectively. As the temperature elevates to 420 °C, all three aging conditions reveal pronounced thermal softening, attributed to high-temperature deformation. At elevated strain rates under room temperature conditions, the yield strength follows the order of T76 > T6 > RRA. However, at 420 °C, with the same high strain rates, the order shifts to RRA > T76 > T6.