Annealing Heat Treatment Research Articles

Achieving an appropriate polarization-breakdown synergy of multilayer films for dielectric energy storage through temperature gradient annealing

Large polarization and high breakdown strength are the key to achieving an idea energy storage density in dielectric capacitors, but unfortunately the trade-off problem between them is difficult to evade, particularly for those dielectrics with different crystalline degrees. Herein, we propose an appropriate polarization-breakdown synergistic strategy of dielectric multilayer films through temperature gradient annealing. The dielectric properties of a serials of (Pb, La)(Zr, Ti)O3/SrTiO3/(Pb, La)(Zr, Ti)O3 (PLZT/STO/PLZT) structures with different annealing temperature for each layer are compared. The optimum recoverable energy density of 57.9 J/cm3 is achieved at a high breakdown electric field of 5.78 MV/cm and a moderate maximum polarization of 22.5 μC/cm2. In addition to the role of suppressing the carriers transport of interlayer STO, the balance between polarization and breakdown strength in bottom and top PLZT layers with individual dielectric characteristics should be responsible for the enhanced energy storage performance (ESP). The results suggest that it is a feasible way to optimize the ESP of dielectric multilayer films through designing different stacking layer via temperature gradient annealing heat treatment.

Influence of Al and Ti Alloying and Annealing on the Microstructure and Compressive Properties of Cr-Fe-Ni Multi-Principal Element Alloy

This study meticulously examines the influence of aluminum (Al) and titanium (Ti) on the genesis of self-generated ordered phases in high-entropy alloys (HEAs), a class of materials that has garnered considerable attention due to their exceptional multifunctionality and versatile compositional palette. By meticulously tuning the concentrations of Al and Ti, this research delves into the modulation of the in situ self-generated ordered phases’ quantity and distribution within the alloy matrix. The annealing heat treatment outcomes revealed that the strategic incorporation of Al and Ti elements facilitates a phase transformation in the Cr-Fe-Ni medium-entropy alloy, transitioning from a BCC (body-centered cubic) phase to a BCC + FCC (face-centered cubic) phase. Concurrently, this manipulation precipitates the emergence of novel phases, including B2, L21, and σ. This orchestrated phase evolution enacts a synergistic enhancement in mechanical properties through second-phase strengthening and solid solution strengthening, culminating in a marked improvement in the compressive properties of the HEA.

Design and Fabrication of a Novel Commercial Baking Oven

This study presents the design and fabrication of a novel wood-fired commercial oven for baking bread. The oven design features an external combustion chamber with heating elements which comprise stainless-steel pipes filled with magnesia starting from the combustion chamber to the 3 oven compartments. Each compartment has 12 heating elements laid under a mild steel sheet metal where the dough mould and its content is placed. Heat loss due to conduction, radiation and convection was prevented by the use of a double wall in both oven and combustion chamber compartments with silica brick and fibre glass respectively, and the oven was fired with wood to bake some dough. Findings showed that maximum temperature attainable by the oven was 700°C, however, the temperature required for baking bread is between 150°C and 180°C and the time was 25 minutes, the quantity of heat generated per time using 10 kg of wood was about 15,088 KJ. Furthermore, the physical appearance of the products was examined to meet consumers’ requirement and a total of 400 bread of 180 mm × 120 mm × 80 mm dimensions can be baked at a time. With slight modifications in the oven design, this number can be improved. The oven can be fired with other types of solid biofuels and can be used for metallurgical furnace applications like annealing, tempering and other heat treatments of metals.

Effect of heat treatment on microstructure and mechanical anisotropy of direct energy deposited Ti-6.0Al-2.5Nb-2.2Zr-1.2Mo alloy

Ti-6.0Al-2.5Nb-2.2Zr-1.2Mo alloy (Ti-6321) exhibits excellent corrosion resistance and impact toughness, which can be used as a deep-sea pressure-resistant hull. However, the alloy tends to have high strength but low plasticity, poor impact toughness, and anisotropic mechanical properties by fabricating by direct energy deposition (DED) technology. In order to improve the impact toughness of DEDed Ti-6321 alloy while reducing its anisotropy of mechanical properties, this study manipulates the microstructure and mechanical properties of the alloy through heat treatment. The research finds that with the increase of the single-stage annealing temperature within the (α+β) two-phase region, the width of the α phase increases, the Ultimate Tensile Strength (UTS) remains essentially unchanged, the Yield Strength (YS) decreases, and the impact absorption energy significantly improves. For double annealing heat treatment at two-phase region, temperature increase at the first-stage annealing enlarges the width and decreases the aspect ratio of the primary α phase. Leading to the decrease of the UTS & YS and increase of the impact absorption energy, with a conversely tendency at 1000 °C. The increase in the second-stage annealing temperature raises the size and volume fraction of the secondary α phase, causing the alloy's UTS and YS to initially rise then fall, with a slight increase in impact absorption energy. The anisotropy in the mechanical properties of DEDed Ti-6321 alloy mainly addressed from the different distribution of α phase orientations at different loading directions, and can be eliminated through sufficient β single-phase zone annealing.

The effect of annealing on the microstructure and wear performance of laser-clad high-entropy alloy composite coatings for monorail crane braking systems

Laser cladding was utilized to fabricate WC ceramic particle-reinforced CoCrFeMnNi high-entropy alloy (HEA) composite coatings, with an investigation into the influence of annealing heat treatment on the microstructure and wear behavior of the composite coatings. The HEA composite coatings with a WC particle content of 30 wt% primarily consist of a face-centered cubic (FCC) solid solution phase, various M6C carbides with blocky, fishbone, and dendritic morphologies, and incompletely melted WC ceramic particles. The microstructure of the composite coatings remains stable up to a temperature of 570°C. After annealing at 600°C, the microstructure transforms into a typical dendritic morphology with rod-like carbides precipitating from the solid solution and discontinuously distributed in the interdendritic regions. Due to the annealing softening effect, the microhardness of the coating decreases from 488.1 HV0.3 to 443.1 HV0.3. Following annealing at a high temperature of 800°C, recrystallization leads to a refined equiaxed grain microstructure, with precipitated carbides continuously distributed along the grain boundaries, forming a network. The combined effects of precipitation hardening and fine grain strengthening result in an increase in the microhardness of the coating to 568.6 HV0.3 after annealing at 800°C. As the annealing temperature increases, the wear rate of the WC particle-reinforced CoCrFeMnNi HEA composite coatings also increase. The wear mechanism for the unannealed coating is oxidative wear, and the reduction in hardness leads to adhesive phenomena in the coating after annealing at 600°C. The network of carbides reduces the ductility of the HEA and also the toughness of the oxide film, resulting in the highest wear rate for the coating annealed at 800°C, reaching 38.636×10−6 mm3/(N·m). This study provides valuable insights for the fabrication of advanced wear-resistant coatings.

Microstructure and properties of TiCuZnSn alloy layer on titanium fabricated by friction stir processing

Surface modification is an effective method to improve the surface properties of biomedical titanium. In this study, TiCuZnSn alloy layer was successfully prepared on pure titanium by friction stir processing (FSP). The grain size of the titanium surface-modified layer was significantly refined, accompanied by the formation of Sn3Ti5 and CuZn phases. After annealing heat treatment, the wear and corrosion resistance of the TiCuZnSn alloy layer was significantly improved compared with that of the titanium substrate.

Effect of dimensional stabilization treatment on mechanical properties of 45% SiCp/Al composites

Abstract With 14μm SiC particles and 2024Al alloy as raw materials, 45% SiCp/Al composites were prepared by hot isostatic pressing method to study the effect of dimensional stabilization treatments on the mechanical properties of composites. The dimensional stabilization treatments used were divided into annealing heat treatment and cold and thermal cycle treatments, and the research method found that the primary annealing treatment decreased the bending strength from 694MPa to 639MPa, and the secondary annealing treatment decreased the bending strength from 863.69MPa to 605MPa. The bending strength decreased from 694 MPa to 639 MPa after the second annealing treatment, and further to 605 MPa after the second annealing treatment. The bending strength of the composites also decreased from 863.69 MPa to 836.16 MPa, and then to 855.54 MPa after solution aging due to the cold and thermal cycle treatments of 120°C to −20°C and 190°C to −196°C, respectively. The micro yield strength increased from 356.57 MPa to 402.66 MPa, and then to 476.03 MPa. The dimensional stabilization treatments included heat treatment, as well as cold and thermal cycle treatments. The cold and thermal cycle treatments further increased the brittleness of the composites after solution aging. Both annealing and cold and thermal cycling reduce the density of the composite, with the annealing resulting in a smaller reduction than the cold and thermal cycling.

Enhancing the machinability and formability of tool steels through spheroidizing annealing heat treatment

This research focuses on enhancing the machinability and formability of tool steels by applying different heat treatment scenarios. Machinability is the process of cutting metals with the least energy effort, while formability is the ability of a metal to be shaped into different forms without severe damage. Enhancing machinability and formability improves dimensional tolerance and surface finish and increases the lifetime and reliability of tool steels. This research will use two tool steel materials, “D2” and “O1,” which are widely used in industry. They contain high percentages of carbon by weight (1.55% and 0.95%, respectively). The “O1” tool steel is used in blanking dies and room-temperature cutting tools, whereas the “D2” tool steel is used for carpentry cutting tools and gauges. The different heat treatment scenarios are based on the latest literature, which shows excellent results with other materials. The heat treatment plan is set to cover various scenarios to determine the most effective treatment for machinability and formability. The experimental work will include several mechanical tests: tensile tests, compression tests, hardness tests, and toughness tests. The conclusions regarding the different heat treatments will be based on the test results.

Pengaruh Variasi Bahan Aditif Pada Base Quench Medium dan Holding Time Tempering Terhadap Sifat Mekanik Material Roda Gigi

Gears are one of the most important components in various machine systems, and in their use, the gears rub and press against each other with other components, so they often experience wear on their surfaces. Therefore, to overcome these problems, the gear material is given a hardening and tempering heat treatment to improve its mechanical properties. The purpose of this study was to determine the effect of variations in cooling media in the quenching process and tempering holding time on the hardness value and impact strength of S45C steel. The method used is S45C steel heated at 950°C for 35 minutes, then cooled using water + 0.12% activated carbon, a 5% NaCl solution, and SAE 15 W 40 oil + 0.12% activated carbon. After that, it was tempered at 260 °C for 15 minutes, 25 minutes, and 35 minutes. Then a hardness test was carried out to determine the hardness value, and an impact test was carried out to determine the toughness value. From the results of the study, it was found that the optimum parameters for overcoming wear problems on gears were using water + 0.12% activated carbon cooling media and a tempering holding time of 15 minutes. From these optimum parameters, it produces a high hardness value of 36.3 HRC and an impact price of 0.23 J/mm².

Influence of martensite and grain size on the mechanical behavior of austenitic Fe–C–Mn–Ni–Al medium Mn steels with TWIP mechanism under uniaxial tension/compression and micromechanical creep

Medium Mn steels with induced plasticity mechanisms have effectively addressed the high-strength and ductility requirements for structural applications. However, there is still uncertainty about the impact of residual martensite on medium Mn steels with an austenitic matrix under uniaxial tension and compression. Furthermore, research on the influence of grain size through incomplete recrystallization in medium Mn alloys is scarce. In this context, our study focused on design and manufacturing a medium Mn Fe–C–Mn–Ni–Al alloy through controlled atmosphere casting incorporating martensite, aiming to analyze its effects under uniaxial stress conditions. Thermomechanical and annealing heat treatments were applied to control grain growth and nucleation of new grains, allowing us to explore how grain size affects the twinning process and mechanical reinforcement in the alloy. Microstructural characterization techniques, including optical and scanning electron microscopy, were employed to assess the mechanical response and damage mechanisms. Mechanical tests included tension, compression, and nanoindentation. The results indicated that residual martensite generates an accelerated damage mechanism under tension due to co-deformation at the interface with austenite, resulting in crack nucleation and rapid propagation through mode I fracture. Consequently, ductility in tension significantly decreases, while no apparent failure is observed during the compression deformation process. Furthermore, incomplete recrystallization was observed to enhance the creep response in both tension and compression. The strain hardening rate results revealed the activation of primary twinning in tension and both primary and secondary twinning in compression for annealed samples. Nanoindentation tests confirmed the presence of twinning and revealed that diffusion creep and grain boundary sliding are the predominant creep mechanisms.

Microstructure, hardness, and wear resistance of high-carbon hypereutectic high chromium irons containing W for use as roller sleeves

High chromium irons (HCI) have rarely been investigated the impact of varying W content on the microstructure and performance of high-carbon irons by scholars. In this study, after calculating by Java-based Materials Properties software (JMatPro), the casting alloying method was applied to explore the effect of adding W (0-15 wt%), Mo 3 wt%, and C 6 wt% on HCI to prepare highly wear-resistant and hard materials. The results showed that the maximum volume fraction of carbide was 38% at C 6 wt%. The addition of W promoted the formation of M6C with a maximum volume fraction of 21%, which increased the hardness to 64.5 HRC and reduced the weight loss to 0.062 g. Since W10 (the iron with W 10 wt%) and W15 (the iron with W 15 wt%) exhibited similar wear resistance but lower impact resistance, the W10 samples were heat-treated. W10 after QT550 (quench and temper heat treatment at 550 °C) sample developed a large number of M6C-type carbides and martensite in the matrix, which improved the properties of the matrix by diffusion strengthening, leading to a hardness of 70.0 HRC and a reduction in weight loss to 0.035 g. Compared to the Cr20 reference iron, W10 after QT550 was 22.8% higher in hardness and 76.8% lower in abrasion. Concurrently, an experiment was conducted on the production of roller sleeves. With the use of W10 after QT550, the lifetime of the roller sleeve was increased by 1.6 times.

Influence of Be Content and T4 Temper Heat Treatment on Hardness and Wear Behavior of Al-Alloy A319

Influence of Be Content and T4 Temper Heat Treatment on Hardness and Wear Behavior of Al-Alloy A319

Effect of Low-Temperature Tempering Temperature on the Mechanical Properties of NM500 Wear-Resistant Steel

Abstract In order to explore the effect of low temperature tempering heat treatment temperatures on Brinell hardness (HB), impact absorption energy (KV2) and tensile mechanical properties of NM500 wear-resistant steel, isothermal tempering heat treatment of NM500 wear-resistant steel sheets after quenching were carried out at 200~260 °C. The microstructures, Brinell hardness, -20 °C impact energies and tensile mechanical properties of NM500 wear-resistant steel after tempered were analyzed by optical microscope, Brinell hardness tester, pendulum impact testing machine and tensile testing machine respectively. The results show that when the tempering temperature increases from 200 °C to 260 °C, the Brinell hardness of NM500 wear-resistant steel decreases from 490 HBW to 460 HBW, the offset yield strength (Rp0.2) decreases from 1396.3MPa to 1351.0MPa, and the tensile strength (Rm) decreases from 1708.5 MPa to 1615.0 MPa. However, the low temperature tempering temperature has no significant effect on the microstructure and elongation after fracture. According to GB/T 24186-2022, 200~220 °C is the suitable low temperature tempering temperature range for NM500 wear-resistant steel.

Optimization of Thermoelectric Properties and Physical Mechanisms of Cu2Se-Based Thin Films via Heat Treatment.

Cu2Se is an attractive thermoelectric material due to its layered structure, low cost, environmental compatibility, and non-toxicity. These traits make it a promising replacement for conventional thermoelectric materials in large-scale applications. This study focuses on preparing Cu2Se flexible thin films through in situ magnetron sputtering technology while carefully optimizing key preparation parameters, and explores the physical mechanism of thermoelectric property enhancement, especially the power factor. The films are deposited onto flexible polyimide substrates. Experimental findings demonstrate that films grown at a base temperature of 200 °C exhibit favorable performance. Furthermore, annealing heat treatment effectively regulates the Cu element content in the film samples, which reduces carrier concentration and enhances the Seebeck coefficient, ultimately improving the power factor of the materials. Compared to the unannealed samples, the sample annealed at 300 °C exhibited a significant increase in room temperature Seebeck coefficient, rising from 9.13 μVK-1 to 26.73 μVK-1. Concurrently, the power factor improved from 0.33 μWcm-1K-2 to 1.43 μWcm-1K-2.

Effect of Self‐Incandescent Heating on Superconducting NbN Nanowire Yarn

AbstractA flexible superconducting yarn composed of twisted niobium nitride (NbN) nanofibrils is developed and exhibited a superconducting transition temperature that met the reported record of ≈17 K. NbN is sputter‐deposited onto a template of aligned single‐layer carbon nanotube (CNT) sheets and subsequently processed by post‐Joule heat annealing following the insertion of twists. Considering self‐Joule heating approaches the level of incandescent light emission, the melting, reflow, and recrystallization of the NbN layer around each CNT template occurred, considerably enhancing the macroscopic superconducting properties of the NbN nanofibrillar yarn, including the critical current density and critical magnetic field. Furthermore, the superconducting performance, which degrades as a result of mechanical damage to the internal structure under excessive stress such as bending, can be restored by the reflow of the NbN during this process. Considering the melting point of NbN is higher than 2800 K, the proposed incandescent light‐emission‐driven Joule self‐heating process is considered an effective method for improving the properties of CNT‐templated metal hybrid yarns.

Impact of annealing on the characteristics of 3D-printed graphene-reinforced PLA composite

Manufacturing through additive techniques, especially utilizing the fused filament fabrication (FFF) method, is a transformative technology revolutionizing design and manufacturing. FFF builds parts layer by layer using thermoplastic polymer and polymer composite filaments. However, weak interlayer connections often lead to low interlaminar resistance in printed structures. Recent studies suggest that post-deposition heat treatments can mitigate this issue by reducing internal thermal stresses and enhancing layer adhesion, thereby improving part properties. This research delves into the impact of annealing heat treatment on a composite of Polylactic Acid (PLA) reinforced with graphene. The annealing process was conducted at temperatures of 90, 100, and 120 °C for durations of 60, 120, and 240 min. The annealing response of the graphene-reinforced PLA composite is compared to that of natural PLA for reference, analyzing its effects on electrical, thermal, chemical, and mechanical properties. Chemical characterization was performed using X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Thermal properties were analyzed via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Electrical properties were assessed by measuring resistance, resistivity, and conductivity. Mechanical properties were evaluated through tensile, flexural, notch sensitivity, impact tests, and hardness measurements. The results demonstrated that annealing of graphene-reinforced PLA and natural PLA did not alter their functional groups but increased their crystallinity. This treatment improved thermal stability, electrical conductivity, and mechanical properties, including tensile strength, flexural strength, and Shore D hardness. However, it reduced impact and notch sensitivity resistances. The increased crystallinity had a greater beneficial impact on some properties than the graphene reinforcement. These findings have potential applications in the automotive, aerospace, electronics, and medical sectors, given the increasing use of PLA in these industries.

Effect of heat treatment on electrochemical behavior of biocompatible Ti–Ta–Nb–Zr alloys prepared by selective laser melting

In this paper, cytotoxicity-free Ti-10Ta-2 Nb-2Zr titanium alloy was prepared by selective laser melting additive manufacturing. The effect of solution and annealing heat treatment on the structure and microhardness were investigated. Electrochemical performance in Ringer’s solution at 37℃ was evaluated. This electrochemical evaluation was performed through the open circuit potential variation as the immersed time, potentiodynamic polarization curves, and electrochemical impedance spectroscopy tests. The results show that main phase composition of as-built and heat-treated specimens was the α/α′ phase. The specimen annealed at 500℃ presented a small amount of β phase. The solutionized and annealed specimens had basket-weave microstructure with distributed micro-scaled α/α′ lamellas. The microhardness of as-built specimens was 400.48 ±12.31 HV. After solution and water quenching, the microhardness dramatically increased to 533.85 ±24.67 HV. The microhardness slightly decreased to 495.46 ±4.85 and 488.8 ±13.84 HV after annealing at 300 ℃ and 500 ℃, respectively. Compared with the as-built specimen, the solutionized and annealed specimens had much lower corrosion current density and higher corrosion resistance.

Preparation of high-strength and high-ductility medium Mn steel with chemistry heterogeneous via a two-step intercritical annealing process

Recently, the retained austenite (RA) with chemically heterogeneous has attracted great attention in medium Mn steel. In this work, we designed a two-step intercritical annealing (TIA) heat treatment process to prepare high-strength medium Mn steel with the chemical composition of Fe–0.20C–8.0Mn–1.6Si–1.3Al (wt.%). Compared with the normal intercritical annealing (IA) heat treatment process, the TIA process can not only increase the volume fraction of RA but also obtain the RA with inhomogeneous Mn distribution. Meanwhile, it was found that the Mn content on the outer side of this structured RA was higher than that on the inner side, forming a nanoscale Mn-enriched layer on the outer side of RA, which played a significant role in improving the stability of RA. Finally, we used the TIA process to obtain medium Mn steel with an ultimate tensile strength (UTS) of 1611.83 MPa, a total elongation (TE) of 45.02%, and a product of strength and elongation (PSE) of 72.56 GPa·%, which achieves a superior combination of high strength and high ductility in medium Mn steel.

The effect of laser surface melting on the microstructure, microsegregation and solidification path of service-aged ECY768 cobalt-based gas turbine nozzle

In this study, the laser surface melting of cobalt-based superalloy ECY768, which has been in service for 40,000 h at a temperature of 1000 °C, has been investigated. Subsequently, laser surface welding and post-welding heat treatment is performed on the samples. This study was conducted in order to restore the microstructure of the damaged service-aged gas turbine nozzle to as-cast state. The results showed that by performing laser surface remelting, the microstructure of as-cast state can be approached. Also, the results of this study have investigated the weldability, microsegregation and solidification path of this superalloy, and it can be used in the repairing this superalloy in the industry. Laser surface melting was performed using a continuous wave fiber laser at various speeds of 10, 12, 14, 20, 50, and 70 mm/s. The microstructure and phase characteristics of the samples were examined using optical and scanning electron microscopes. Upon analyzing the macrostructure of the weld metal, it was observed that the depth of the melt zone at the speed of 12 mm/s is 585 ± 40 μm. In the investigating the microstructure of the solidification modes, namely planar, cellular, columnar dendritic, and equiaxed dendritic, it was observed that microsegregation occurs during laser welding of the samples due to the presence of heavy elements such as tantalum and tungsten. The solidification distribution coefficient for tantalum was calculated to be 0.37, which increased to 0.60 after the solution annealing heat treatment, resulting in an improved segregation behavior. Characterizing the surface hardness profiles of laser-melted samples it was observed that the hardness in the melt zone significantly increased compared to the base metal. The results of the current research indicate that the weldability (resistance to various welding defects, especially hot cracks) of the cobalt-based superalloy ECY768 is acceptable, and this process can be used for rejuvenating service-aged ECY768 cobalt-based gas turbine nozzle.

Mechanical properties of spinel (MgCr2O4) phase containing alumino-silicate glass-ceramic

This research study explores the addition of chromium (Cr6+) ions as a nucleating agent in the alumino-silicate-glass (ASG) system (i.e., Al2O3-SiO2-MgO-B2O3-K2O-F). The important feature of this study is the induction of nucleation/crystallization in the base glass matrix on addition of Cr6+ content under annealing heat treatment (600 ± 10 °C) only. The melt-quenched glass is found to be amorphous, which in the presence of Cr6+ ions became crystalline with a predominant crystalline phase, Spinel (MgCr2O4). Microstructural experiment revealed the development of 200–500 nm crystallite particles in Cr6+-doped glass-ceramic matrix, and such type microstructure governed the mechanical properties. The machinability of the Cr-doped glass-ceramic was thereby higher compared to base alumino-silicate glass (ASG). From the nano-indentation experiment, the Young’s modulus was estimated 25(±10) GPa for base glass and increased to 894(±21) GPa for Cr-doped glass ceramics. Similarly, the microhardness for the base glass was 0.6(±0.5) GPa (nano-indentation measurements) and 3.63(±0.18) GPa (micro-indentation measurements). And that found increased to 8.4(±2.3) (nano-indentation measurements) and 3.94(±0.20) GPa (micro-indentation measurements) for Cr-containing glass ceramic.