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This study investigates the effects of different lubrication conditions on drawing force and microcup formation during micro deep drawing (MDD). Results show that graphene lubricant, in combination with TiO2 nanolubricants, has the potential to reduce friction during MDD. The peak drawing force was reduced by 15.39% when both lubricants were used together, while the use of TiO2 nanolubricant and 10.0 mg/ml graphene lubricant reduced it by 6.03% and 14.52%, respectively. The study also reveals that lubricants reduce wrinkling during the formation of microcups by minimising energy consumption during the primary formation. However, the combination of TiO2 nanolubricant and graphene lubricant can cause inhomogeneous formation on the upper part of the blank, leading to more apparent wrinkling. Overall, the study highlights the potential of TiO2 nanolubricant and graphene lubricant in reducing friction and improving microcup formation during MDD. [ABSTRACT FROM AUTHOR]

In recent years, the quest for effective lubrication in micro deep drawing (MDD) has seen promising advancements. In this study, the influence of TiO2 nanolubricants and graphene lubricants on the performance of 301 stainless steel foil in MDD is examined. The MDD undergoes an extensive evaluation of various lubrication conditions, including dry, TiO2 nanolubricant, graphene lubricant at concentrations of 2.5 mg/mL, 5.0 mg/mL, and 10.0 mg/mL, as well as combined applications of TiO2 and graphene lubricants. Utilising a 5.0 mg/mL graphene lubricant together with TiO2 nanolubricants led to a significant reduction in drawing force, highlighting the synergistic efficacy of this combined lubricant. A pronounced enhancement in the consistency of the produced microcups was also attained. These results emphasise the promise of TiO2 nanolubricant and graphene lubricants in optimising the MDD process. [ABSTRACT FROM AUTHOR]

The long, straight grain boundary of the high-entropy alloy (HEA) produced via laser melting deposition (LMD) is prone to cracking due to unidirectional scanning (single wall). To enhance the competitive growth of columnar grains and improve the overall performance of the alloy, a vertical cross scanning method was employed to fabricate FeCoCrNi HEA (bulk). The influence of grain orientation on the microstructure and mechanical properties of FeCoCrNi-LMD was systematically investigated. Microhardness tests and tensile tests were conducted to assess the mechanical property differences between the single-wall and bulk samples. This study shows that using a single scanning strategy results in monolayer wall grains sized at 129.40 μm, with a max texture strength of 21.29. Employing orthogonal scanning yields 61.15 μm block-like grains with a max texture strength of 11.12. Dislocation densities are 1.084 × 1012 m−2 and 1.156 × 1012 m−2, with average Schmid factors of 0.471 and 0.416. In comparison to the FeCoCrNi-LMD single wall, the bulk material produced through cross-layer orthogonal scanning exhibited reduced residual stress, weakened anisotropy, and improved mechanical properties. These findings are expected to enhance the potential applications of FeCoCrNi-LMD in various industries. [ABSTRACT FROM AUTHOR]

At present, Al matrix composites (AMCs) have drawn much attention owing to their light weight, high specific strength, high thermal conductivity, and superior excellent wear resistance, which endows them with great potential in the aerospace, automobile and military industries. In this study, AMCs with different Ti contents (0, 5 and 10 vol.%) were prepared by powder metallurgy. During the sintering, Al3Ti particles were in situ formed in the Al matrix. It was found that the Ti completely reacted with the Al matrix and formed fine in situ Al3Ti particles in Al-10Ti, while some large Ti-Al3Ti core-shell formed in Al-5Ti due to the incomplete reaction between the Ti and the Al matrix. Furthermore, the hardness of the composites was significantly improved by the in situ formed Al3Ti particles, reaching 143.3 HV in Al-5Ti and the highest value at 331.2 HV in Al-10Ti, respectively. The wear resistance of the composites is remarkably enhanced by Al3Ti particles compared to the unreinforced Al. Al-5Ti has the highest wear resistance among the samples. The wear resistance of the Al-10Ti composite becomes slightly deteriorated compared to Al-5Ti due to the brittle nature of Al3Ti, which leads to a three-body abrasive wear. [ABSTRACT FROM AUTHOR]

To improve the quality of products produced from microforming, various nanolubricants have been applied in the field of micromanufacturing in recent years. In this paper, the effects of glycerol-based lubricant containing TiO2 NPs (NPs) on micro deep drawing (MDD) of austenitic stainless steel (ASS) SUS301 were studied, and the lubrication mechanism involved was discussed. The MDD experiments were conducted with the SUS301 foils under dry, 1, 2, and 4 wt% TiO2 NP lubrication conditions. The results show that the use of the TiO2 nanolubricants can significantly improve the quality of the drawn cups in terms of decreased wrinkling and surface roughness. Besides, the concentration of TiO2 NPs influences lubricity by reducing friction during the MDD process. The peak drawing force is the lowest when 2 wt% nanolubricant is applied, which drops to 72.54 N from 77.38 N under dry conditions. The micro cup drawn under 2 wt% TiO2 nanolubricant has the best quality among those obtained under all the lubrication conditions. The lubrication mechanisms are derived from the mending effects of TiO2 NPs and the formation of thin lubricant films associated with the open lubricant pockets (OLPs) and close lubricant pocket (CLPs) theory in the MDD. The CLPs function as reservoirs that retain lubricants to counteract the load pressure, whereas the OLPs lead to lubricant leakage due to the higher flow resistance. It was found that the lubricant film and NPs are insufficient at a low concentration (1 wt%), while the lubrication performance can be enhanced with increased NP concentration. However, there exist apparent agglomerations on the surface of the produced micro cup when using 4 wt% nanolubricant, which greatly deteriorates the lubricant performance in the MDD process. It is concluded that the lubricant containing 2 wt% TiO2 NPs demonstrates the best lubrication performance during the MDD of ASS SUS301. [ABSTRACT FROM AUTHOR]

Micro deep drawing (MDD) is a fundamental process in microforming which has wide applications in micro electromechanical system (MEMS) and biological engineering. Titanium possesses excellent mechanical properties and biocompatibility, which makes it a preferred material in micromanufacturing. In this study, eco-friendly and low-cost water-based TiO2 nanolubricants were developed and applied in the MDD with 40 μm-thick pure titanium foils. The lubricants consisting of TiO2 nanoparticles (NPs), 10 wt% glycerol, 0.1 wt% sodium dodecyl-benzene sulfonate (SDBS) and balanced water were synthesised in a facile process. The MDD with 40 μm-thick pure titanium was carried out using the lubricants with varying concentrations of 0.5, 1.0 and 2.0 wt%. The results show that the formability of micro cups could be significantly improved when the nanolubricants are applied. Especially, the use of 1.0 wt% TiO2 nanolubricant demonstrates the best lubrication performance by significantly reducing the final drawing forces, and surface roughness, and the wrinkles by up to 24.2%, 12.55% and 4.82%, respectively. The lubrication mechanisms including the ball bearing and mending effects of NPs on open lubricant pockets (OLPs) and close lubricant pockets (CLPs) areas were then revealed through microstructure observation. [ABSTRACT FROM AUTHOR]

The microstructure of Cr–Mn–Ni–N stainless steel is regulated by a combination of cold deformation and subsequent martensite reversed annealing. The yield strength and tensile strength of the tested steel are greatly improved to 1220 and 1357 MPa, respectively, by conventional heavy cold rolling (66% thickness reduction) and a subsequent annealing process (750 °C for 5 min) relative to those before cold rolling (austenized state); at the same time, the total elongation keeps an appropriate value. The results show that the grain refinement strengthening acts as the primary factor for the strengthening of the tested steels while the precipitation behavior from the M23C6‐type carbides is not quite effective. Additionally, different yield phenomena and microstructural evolution for tested steels with 66% thickness reduction annealed at 750 °C with different holding times are systematically analyzed and discussed. Lüders‐like deformation features noticeably appear but become weakening with the longer annealing time. The change in initial free mobile dislocation density is the core cause of the preyield plateau phenomenon. [ABSTRACT FROM AUTHOR]

In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimised sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies. [ABSTRACT FROM AUTHOR]

Micro forming is a promising technology with the trend towards miniaturisation in industry, and micro deep drawing (MMD) process is a fundamental micro forming method with potential applications in forming of cups, hollows and boxes and has great advantages comparing to other micro manufacturing methods. As the preferred material for electrical conductors, aluminium (Al)-copper (Cu) composite material processes advantages of the low density and cost of aluminium and good conductivity of copper. In this paper, MMD has been studied experimentally and numerically with a purpose of understanding the deformation behaviour of a two-layer Al-Cu composite in microscale. Al-Cu composite material was rolled to 50 µm in thickness and then annealed at 400 ºC. The drawability of the annealed composite was investigated by MDD experiments. FE models with Voronoi tessellations were established to simulate the Al-Cu composite material during MDD process. Considering the grain heterogeneity, each Voronoi tessellation has been assigned with different mechanical properties based on experimental data. The simulation results are in good agreement with the experiment ones. [ABSTRACT FROM AUTHOR]

A new hot forming process of a hot-rolled 2205 duplex stainless/AH36 low-carbon steel bimetal composite (2205/AH36 BC) was proposed in this study, using the Gleeble 3500 thermal-mechanical simulator and hot bending tools. The deformation characteristics of 2205/AH36 BC were studied by hot tensile tests at temperatures from 950 to 1250 °C and strain rates ranging from 0.01 to 1 s−1. The tensile temperature has a great influence on the peak flow stress of the bimetal composite. The main microstructure evolution mechanisms, including dynamic recovery (DRV) and dynamic recrystallization (DRX), changed with the deformation temperatures. The different strain rates and the change of strain rates during the deformation process have an influence on the flow behavior of the bimetal composite. During the hot bending process, qualified parts could be formed successfully without obvious cracks in the interfacial zone. Phase and grain orientation spread (GOS) maps of specimens after hot tensile and forming tests were obtained by the electron backscatter diffraction (EBSD) technique to study the microstructure evolution, respectively. It is found that the effect of the working temperature on microstructure evolution is larger than that of the stacking sequence for 2205/AH36 BC. The considerable geometrically necessary dislocation (GND) accumulation occurs around the interface of 2205/AH36 BC under all imposed working conditions after the hot bending process, due to the interfacial micro-defects and complex stress states. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al2024-TiC-GNPs hybrid composite was produced via powder metallurgy. • Presence of both TiC and GNPs contributes to refining matrix powders after milling. • Distributions of Al 2 Cu, TiC and GNPs are improved by adding both TiC and GNPs. • Synergetic effects of TiC and GNPs benefit the wear resistance of hybrid composite. Al matrix composites have attracted significant attention of researchers in recent years due to their lightweight, excellent mechanical and tribological properties. In this study, an Al2024 matrix hybrid composite (AMHC) reinforced with both TiC nanoparticles and graphene nanoplatelets (GNPs) was produced via a route of powder metallurgy. And its microstructure, microhardness and tribological properties are compared with those of unreinforced Al2024 alloy matrix and Al2024 matrix composites reinforced with either only TiC or GNPs. It was found that the distribution of Al 2 Cu, TiC nanoparticles and GNPs in the matrix and the wear resistance are significantly improved when introducing both TiC nanoparticles and the GNPs. The wear mechanisms change from the adhesion-dominant wear for Al2024 and the other singly reinforced composites into abrasive-dominant wear for the hybrid composite. The significantly improved wear resistance of the AMHC is attributed to the synergistic effects of reinforcing and self-lubricating of the TiC and GNPs. [ABSTRACT FROM AUTHOR]

Abstract The microstructure and texture after plastic deformation are strongly dependent on the corresponding manufacturing process and subsequent annealing which significantly affect the properties of the final products. In this study, 1060 aluminium alloy with a thickness of 464 μm was micro flexibly rolled to a constant thickness ratio of 3.6 by a combined control of the roll gap, the rolling speed and the roll lifting speed. Afterwards, the rolled specimens were subjected to isochronal annealing at a temperature range of 200 to 400 °C for 30 min and isothermal annealing at 400 °C for 10–60 min. Results indicate that the microstructure, microhardness and texture of each thickness zone are distinctly influenced by the rolling parameters and annealing conditions. Specimens annealed at 400 °C for 30 min result in a relatively steady hardness distribution along the transition zones. Typical β fibre texture is observed in the specimens suffered from annealing while S is predominant in both micro flexibly rolled and annealed specimens. Highlights • Inhomogeneous behaviour of aluminium alloy after micro flexible rolling and annealing • Microstructure and texture evolution along the varying thickness zones of micro flexibly rolled strips • The mechanics based on the special deformation features was proposed. • Isothermal and isochronal annealing on the recrystallised characteristics of thin varying thickness strips [ABSTRACT FROM AUTHOR]

Micro-hydromechanical deep drawing (MHDD) is a promising micro-manufacturing technology to fabricate micro-metallic products in batch scale. Size effects significantly affect MHDD regarding both material properties and friction. Hydraulic pressure on the blank and its development differ from that in conventional hydromechanical deep drawing. Combined influence of fluid pressure, surface roughness and material inhomogeneity of the blank was investigated in this study via MHDD experiments and advanced FE simulation considering strong fluid-solid interaction (FSI) and size effects. The MHDD experiments under different hydraulic pressures were conducted using the annealed foil followed by the advanced FE simulation. The foil can be successfully drawn into micro-cups, however, wrinkles occurred under high hydraulic pressures. Wrinkle height and number are affected by hydraulic pressure and size effects. Average hydraulic pressure on the blank is lower than the inlet pressure, and pressure development on the blank depends on location and is complex, due to transition of sealing between the blank and die. The maximum drawing force increases, while the contact forces and pressures on the blank holder and die decrease with an increase of hydraulic pressure. Optimal hydraulic pressure for MHDD should be determined with consideration of size effects and MHDD tool geometry. • Micro-hydromechanical deep drawing experiments and advanced simulation with consideration of FSI, material surface morphology and inhomogeneity were conducted. • Change of the sealing between the blank and die significantly affects mean and local hydraulic pressure development on the blank, which further impacts MHDD. • Hydraulic pressure reduces contact forces and maximum contact pressures on both blank holder and die, which benefits wear behaviour of MHDD tools. • Integrated effect of hydraulic pressure and size effects influences wrinkling. • Optimal hydraulic pressure should be determined with consideration of foil's properties and MHDD tool geometry. [ABSTRACT FROM AUTHOR]