This study presents a high-frequency heat-assisted incremental bending process for the high-efficiency, high-precision forming of medium-thickness (≥3 mm) double-curved metal plates, addressing the limitations of traditional stamping and line heating methods in aerospace and marine applications. A minimum energy loading path strategy is proposed to optimize the forming trajectory and reduce residual stress. A coupled thermomechanical finite element model was developed, incorporating high-frequency induction heating, temperature-dependent material properties, and Coulomb friction. The model was validated through experiments on Q235 steel plates. Results show that the proposed process reduces the peak forming force and decreases the number of forming points compared to conventional cold incremental bending. Springback is reduced, and the final shape accuracy reaches within 3 mm deviation from the target geometry. Double-curvature sail and saddle-shaped plates were successfully fabricated, demonstrating the feasibility and effectiveness of the method. This work provides a promising solution for low-cost, flexible manufacturing of complex medium-thickness components.

FEM simulation and experimental validation of a high-frequency induction heating system with COMSOL Multiphysics

Ultrafast healing of micro-pores in cold-sprayed CuCrZr-W composite coatings via high-frequency induction heating

Enhancing Al-Cu Alloys Produced by High-Energy Milling and Sintered by High Frequency Induction Heating for Microstructure Control

Технологии высокочастотного индукционного нагрева получили широкое распространение в процессах сверхчистой бесконтактной плавки, сварки металлов и термообработки деталей машин сложной формы, при обработке мелких деталей, которые могут повредиться при газопламенном или дуговом нагреве. Цель исследования – разработка и исследование характеристик индукционной электронагревательной установки. Задачи исследования – разработать структурную и принципиальную схемы индукционной установки, провести экспериментальные исследования ее характеристик. Для исследования режимов индукционного нагрева была разработана лабораторная установка, позволяющая измерять температуру нагреваемой заготовки и индуктора; регулировать частоту тока; измерять токи первичного звена и индуктора; устанавливать режим максимальной эффективности. В ходе эксперимента были проведены измерения температурной характеристики в зависимости от времени при разных диаметрах заготовки и разных токах индуктора; измерение скорости нагрева в зависимости от диаметра заготовки при разных токах индуктора. Анализ исследований позволяет сделать вывод, что с увеличением диаметра заготовки увеличивается время ее прогрева до установленных температур (в пределах 150…350 °С, в зависимости от диаметра заготовки). Увеличение тока индуктора в начальный момент нагрева до 120 с незначительно повышает температуру заготовки. С увеличением времени нагрева повышение тока индуктора с 15 до 30 А увеличивает температуру заготовки на 30 °С. Скорость нагрева на заготовке диаметром 17 мм при повышении тока индуктора на 1 А увеличивается на 0,01 °С/с, а на заготовке диаметром 10 мм – на 0,08 °С/с. Таким образом, разработанная лабораторная установка позволяет исследовать основные режимные параметры индукционного нагрева, в том числе температурные характеристики нагрева в зависимости от диаметра заготовки и тока индуктора. Полученные результаты могут использоваться для проектирования и выбора режимных параметров установок индукционного нагрева. High-frequency induction heating technologies are widely used in the processes of ultra-clean contactless melting, metal welding and heat treatment of complex machine parts, when processing small parts that can be damaged by gas flame or arc heating. The purpose of the study is to develop and study the characteristics of an induction electric heating unit. The objectives of the study are to develop a structural and basic diagram of the induction unit, and to conduct experimental studies of its characteristics. To study the induction heating modes, a laboratory setup was developed that allows measuring the temperature of the heated workpiece and the inductor; adjusting the current frequency; measuring the currents of the primary link and inductor; setting the maximum efficiency mode. During the experiment, the measurements of the temperature characteristic depending on time at different diameters of the workpiece and different inductor currents, and the measurements of the heating rate depending on the diameter of the workpiece at different inductor currents were carried out. The analysis of the studies allows us to conclude that with an increase in the diameter of the workpiece, the time of its heating to the set temperatures increases (within 150…350°С depending on the diameter of the workpiece). An increase in the inductor current at the initial moment of heating to 120 s slightly increases the temperature of the workpiece. With an increase in the heating time, an increase in the inductor current from 15 to 30 A increases the temperature of the workpiece by 30°С. The heating rate on a workpiece with a diameter of 17 mm with an increase in the inductor current by 1 A increases by 0.01°С/s, and on a workpiece with a diameter of 10 mm – by 0.08°С/s. Thus, the developed laboratory setup allows us to study the main operating parameters of induction heating, including the temperature characteristics of heating depending on the diameter of the workpiece and the inductor current. The results obtained can be used for designing and selecting the operating parameters of induction heating units.

Numerical calculation of high frequency induction heating for complex hull plate considering deflection

ABSTRACT This study examines the formation of fayalite (Fe₂SiO₄) during the direct reduction of iron ore composite briquettes using resistance heating, microwave heating, and high-frequency induction heating. Direct reduction, a crucial process for producing metallic iron below 1200°C, is significantly influenced by fayalite formation, which affects reduction efficiency and product quality. The impact of different heating methods on phase transformation and microstructural evolution was analysed. Induction heating exhibited the most effective reduction, generating intense localised heat that facilitated near-complete conversion to metallic iron with minimal residual fayalite. Microwave heating significantly accelerated reduction due to volumetric heating, reducing processing time, though some residual fayalite and wüstite remained. Resistance heating provided a stable and controlled thermal environment but resulted in the slowest reduction and the highest fayalite retention. The study highlights the role of heating techniques in phase evolution, emphasising the need for precise thermal control to optimise reduction conditions. These findings offer valuable insights into selecting appropriate heating methods to enhance reduction efficiency, control phase formation, and improve the metallurgical properties of reduced iron. Understanding and mitigating fayalite formation is crucial for advancing direct reduction technologies, improving energy efficiency, and supporting more sustainable iron-making processes.

Rapid sintering of SiC ceramics assisted by high-frequency induction heating

Nowadays, there is a growing need for using functionally graded materials (FGM) for using in bio-medical application. This need is prominent especially for the effect of gradient structures and in implant applications. To optimize both mechanical and biocompatibilities properties or change bio reactivity in each region, powder metallurgy technique is used in this study to fabricate titanium/hydroxyapatite (Ti/HAP) and other FGM implants with the concentration changed gradually in the longitudinal direction of cylindrical shapes. Concentration gradient was formed by packing dry powders into mold or sedimentation in solvent liquid processes. For the sintering process, three spark plasma sintering (SPS), high-frequency induction heating and electric furnace heating techniques were used to sinter the materials. During the fabrication of Ti/HAP FGMs and due to the stress relaxation in the implanted regions of bones, Brinell hardness decreased gradually from Ti part to HAP part. The results showed that the tissue reaction occurred gradiently in response to the graded structure of the FGM, which implies the possibility of controlling the tissue response through the gradient function of the FGM.

This paper reviews the current state of research on half-bridge (HB) inverters used in induction heating power supplies, emphasizing their topological structures, output power control methods, and switching strategies. The study explores various control techniques to regulate low power levels in a series resonant inverter (SRI) configured with an HB structure for induction heating applications. Pulse frequency modulation (PFM) is commonly employed to regulate standard power levels by adjusting the operating frequency relative to the resonant frequency. As the operating frequency increases beyond resonance, the output power decreases. However, in certain scenarios, achieving low power levels necessitates high frequencies, which introduces significant control challenges. To address these issues, it is crucial to develop alternative approaches that ensure efficient power reduction, without compromising system performance. This work evaluates and compares multiple solutions tailored for a high-frequency induction heating system delivering 18 kW at an operating frequency of approximately 100 kHz. The study places particular emphasis on optimizing key component sizing and analyzing inverter losses to enhance overall system efficiency and reliability.

This study demonstrates rapid carbon nanotube (CNT) synthesis using a 150 kHz induction heating system, enabling precise temperature and pressure control in thermal chemical vapor deposition processes. CNT growth optimization at temperatures between 887 and 955 °C and pressures from 1 to 700 Torr reveals that an optimized temperature (887 °C) and pressure (100 Torr) yield enhanced field emission performance. The 150 kHz induction heating provided faster heating rates and a more consistent temperature distribution across the substrate, significantly enhancing growth efficiency. CNT grown using the induction heating system demonstrated high emission currents and outstanding stability during field emission tests. The induction heating approach reduces synthesis time, offering an efficient pathway for scalable production of field emission devices.

The increasing deterioration of ageing reinforced concrete road bridge slabs in Japan has necessitated their replacement to ensure user safety. Currently, various rationalized joints using mechanical anchorage rebars have been developed, but most rely on rebar with post-installed anchorage, with few utilizing integrally formed anchorage zones for higher fatigue durability. In this study, a mechanical anchorage rebar with an anchorage zone integrally formed by high-frequency induction heating was developed. To verify its applicability to the joints between precast concrete slabs, the mechanical anchorage rebar underwent rebar tensile, static bending, wheel-load running, and water leakage tests. The results confirmed the developed rebar fractured at the base material. In addition, a static bending test of the joint confirmed that the load-carrying capacity of the slab joint using the rebar was maintained even after the member yielded. The wheel load running test using a full-scale specimen showed no failure under loading conditions. No water leakage from the underside of the slab was observed in the water leakage test on the upper surface of the slab. Furthermore, no punching shear failure occurred after accelerated fatigue loading, confirming that the slab joints with the developed mechanical anchorage rebars exhibited high fatigue durability.

Continuous Welding Behavior of Woven-CF/PPS Laminates Using 2MHz Band High-Frequency Induction Heating

Utilizing a multi-wire arc additive manufacturing process applied with high-frequency induction heating wire technology (MWAAM-HF) proposed in this study, Ti-48Al-2Cr alloy straight-walled component was fabricated. During the MWAAM-HF process, three types of wires melt simultaneously and transfer smoothly into the weld pool to form satisfactory component without discernible cracks. The upper and lower regions have higher hardness compared to the middle region in both Z and Y direction. Along the Y direction, the upper region exhibited the highest UTS and YS, while the minimum values were observed along the Z direction. Superior wear resistance was observed in the upper and lower regions. Distinct regions exhibited different levels of high-temperature oxidation resistance and the upper region has superior high-temperature oxidation resistance.

This study investigates the application of hot bending–quenching technology to heat-treatable A6063 aluminum tubes, focusing on the bending formability and mechanical properties after aging treatment under various heating conditions. High-frequency induction heating was used to uniformly heat aluminum tubes to the solution treatment temperature of 560 °C. The effect of wall thickness on bending formability was explored, revealing that thinner tubes (2 mm) experienced significant flattening defects, whereas thicker tubes (5 mm) exhibited superior formability with reduced shrinkage and wall thinning. Additionally, the pre-quenching temperature was found to influence the mechanical properties of the tube with a thickness of 5 mm. Tubes held at the solution temperature for 1 min 30 s or longer maintained higher temperatures during transfer, resulting in improved tensile strength and hardness after aging. The findings confirm the feasibility of applying hot bending–quenching technology to aluminum tubes, though careful control of temperature loss during continuous industrial processes is required to ensure optimal mechanical performance.

The process of high-frequency induction heating of the inner rings of bushing bearings before disassembly, which is carried out during the repair work of wheel pairs of subway cars, has been investigated. Physical modeling of the heating process was carried out at a frequency of 10 kHz and using an inductor with a three-row winding of 17 turns, the length of which was equal to the length of the ring. It is shown that when varying the heating time and the power transmitted to the part, it is not possible to ensure the selection of an acceptable heating mode for normal disassembly from the point of view of ensuring repeatability of results and preventing local overheating of the part. Calculations were carried out in the COMSOL environment on the finite element model of the process of heating the ring of a bushing bearing with a constant number of turns for different variants of the geometry of the inductor winding, that is, the number of winding rows, the number of turns in a row and their location relative to the inner rings of the bearings. It is shown that the geometric shape of the inductor winding has a significant effect on the distribution of specific heat emissions along the surface of the parts. The optimized geometry of the winding was determined, which ensures the necessary heating dynamics and the absence of local overheating zones of the bearing rings, which allows to reduce the proportion of rejected parts. Ref. 5, fig. 6, table.

The application of induction heating power supply in the continuous production line of tinplate has garnered significant research and scholarly attention. However, the impedance matching of LC or CLC resonant circuits in the system lacks flexibility and is susceptible to overvoltage during startup. As a solution to the problem, a novel four-order LCLC parallel resonant circuit was proposed in this study for high-frequency induction heating power supply. By incorporating auxiliary inductors in parallel with CLC compensating capacitor branches, the induction heating system can operate reliably and achieve optimal load impedance matching. The equivalent circuit and mathematical model of the new resonant load were established, and the frequency characteristics of the circuit system were analyzed. Then, the parallel resonance characteristics of the new resonant circuit were comprehensively elucidated, including the quality factor, impedance characteristics, behavior of resonant current, and properties of voltage regulation. Finally, a simulation model of a high-frequency induction heating power supply was developed based on the proposed LCLC resonant circuit and compared with LC and CLC resonant circuits. The results demonstrated that the induction heating power supply system utilizing the proposed LCLC parallel resonant load exhibits superior parallel resonant characteristics, enhanced load impedance-matching flexibility, and improved output voltage stability when compared to traditional LC or CLC parallel resonant loads.

ABSTRACT A high-frequency induction heating (HFIH) system is a novel and clean heat source that can potentially melt high melting point material to develop the wire feed-based additive manufacturing (AM) process. The present study establishes the optimised coil parameters, including coil geometry for melting the titanium wire using induction heating. A fully coupled electromagnetic-thermal-fluid flow model is established to analyse the temperature profile of the wire. The wire feed velocity (0.012 m/s) is incorporated in the coupled model using the deformed mesh method. Optimised wire diameter and coil parameters, such as a three-turn helical coil with a circular cross-section, coil turn spacing of 1.5 mm, and a coupling distance of 4 mm, melt the 3.6 mm titanium wire rapidly and create the molten droplet. The results suggest that the optimised coil parameters improve the magnetic flux density, which enhances joule heating in the wire. However, the conical-spiral coil geometry of the three-turn fails to melt the wire completely. In contrast, the helical coil of the three-turn melts the wire completely. The maximum velocity of the molten metal is found as 0.25 m/s. Effectively, the heat transfer and material flow analysis drives to develop the potential additive manufacturing system.

<p>本文旨在發展應用於感應加熱系統之相移全橋換流電路，本文所提電路使用串聯諧振配合負載線圈電壓、電流相位控制迴路，能在負載溫度控制過程，克服感應熱負載阻抗特性變化，達到換流電路零電壓切換，同時使得負載之工作溫度得穩定在設定值。本文除理論分析外，所提方法已於實驗室完成雛形電路進行驗證，由實驗證實雛形電路500W轉換效率93.4%、160℃溫度控制誤差4.3℃，相關實驗結果顯示所提方法在感應加熱系統之應用確具可行性與實用參考價值。</p> <p> </p><p>This paper aims to develop an inverter circuit for induction heating. The proposed phase-shifted full bridge inverter utilizes series resonance to provide zero-voltage switching (ZVS) for the switching devices. By studying the voltage and current of resonance circuit along with relationships between load impedance and frequency, the working frequency and resonant current phase in the circuit can be well controlled for ZVS. Moreover, the paper has developed the temperature control loop, where software simulations and experimental measurement are both made to evaluate. Results from simulations and hardware testing is compared with each other, thereby verifying the concepts introduced in this paper.</p> <p> </p>

Induction assisted autogenous plasma arc welding of HSLA steel