高速锻造

No abstract available

This study investigates the influence of die velocity in sinter forging, particularly focusing on plastic deformation characteristics in the cold forging of axially symmetric components. Key factors such as material flow, inertia energy dissipation, and die load are examined. Results show that both energy dissipation and die load increase with higher die speeds. Utilizing an upper-bound approach with a simplified velocity field, theoretical results for the average die load are established. This analysis aims to improve the understanding of dynamic effects in sinter-forging cylindrical preforms, offering valuable insights for future research in this domain. Additionally, this paper provides a comprehensive review of the role of friction in metal forming processes, emphasizing the development of theoretical models to analyze tool-workpiece interfaces under varying friction conditions using the upper-bound method. The importance of understanding friction, particularly in forging processes, is highlighted. A composite friction mechanism in axisymmetric forging is introduced, accounting for the effect of platen speed. The significance of friction conditions on key factors such as applied load and plastic deformation is underscored, particularly considering the crucial interaction between adhesion and sliding.

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The development of high-speed railways (HSR) is an important task aimed at improving the transport system of today’s global community. The most heavily-loaded element of HSR, governing their reliability and lifetime, is a contact wire. In this connection, the present study was focused on designing a new set of physico-mechanical properties of a wire made from the heat-treatable Cu-0.65Cr alloy with the use of a new procedure of continuous plastic processing, based on the principles of severe plastic deformation. Thus, an important difference from the common technical solutions used in the production of wires was the use of a combination of SPD processes – radial forging and ECAP-Conform, joined with the shape-forming of shaped sections of wire. In our study, we performed finite-element computer and physical modeling of the processes of plastic and heat treatment. Using computer modeling, we demonstrated that as a result of the implementation of the new procedure of continuous processing, a rather homogeneous strained state is formed in the workpiece, and the accumulated strain is in a range of e = 6-7. At all stages of plastic processing, compressive stresses prevail in the deformation site. As a result of physical modeling, we produced laboratory samples of contact wire from the heat-treatable Cu-0.65Cr alloy with a cross-section area of 150 mm2. Metallographic studies reveal that a banded structure of a grain-subgrain type with a fragment size below 1 micron is formed in the laboratory samples of contact wire. The ultimate tensile strength of these samples after heat treatment is 550-560 MPa, the electrical conductility is 72-75% IACS, the ductility is 16-20%.

The study refers to a comprehensive analysis of the occurrence of defects in forgings constituting elements of window fittings, for which, in the process of their production through precision die forging in a six-impression system at elevated temperatures on a hydraulic hammer, we observe bending of the whole forged element and tilting of the stem (a conical element protruding in a plane perpendicular to the main axis of the forging) in the particular forgings. The investigations included analysis of the technology of precision forging on a hydraulic hammer with an energy of 16 kJ, advanced numerical simulations of the process with the use of a calculation package Forge 3.0 NxT, and dynamic tests of mutual displacement of tools performed by means of a high-speed measurement camera. Preliminary analysis of the process showed that, for forgings with a narrowed dimensional and shape tolerance, produced dynamically on a hammer, the key role is played by elastic deformations as well as the construction of the dies and the geometry of the working impressions, and also the changing tribological conditions. For this reason, multi-variant numerical simulations, including two variants of tools (the standard process and the so-called broken perpendicular flash), were carried out, which made it possible to determine the temperature and forging force distribution in the tools as well as the correctness of the deformed forging material’s flow, the filling of the working impressions, and the defects in the forgings. Next, with the use of a high-speed camera, measurements of the relative displacement of the dies were performed, which showed that a proper change in the construction (geometry) of the tools and the use of locks positively affects the minimization of the displacements and thus increases the quality and dimensional and shape precision. The proposed approach using numerical simulations and dynamic measurements of displacements allows for a relatively quick analysis and the introduction of necessary changes in the technology, including modifications of the construction and geometry, in order to minimize the forging defects. That said, the obtained results did not unequivocally point to one specific optimal solution; therefore, the issue of a total elimination of forging defects is still open and constitutes a scientific challenge. And so, further research and verification studies are required to improve the current forging technology and eliminate forging defects in multiple systems in longer operational periods.

This paper explores various aspects of bulging in high-speed sinter-forging across different relative densities. The forging process of sintered preforms involves significant energy dissipation, affected by factors like die speed, bulging coefficient, initial relative density, and height reduction. High die speed results in increased frictional energy dissipation, leading to surface heating and bulging. Moreover, there is a notable increase in energy dissipation, die load, and frictional energy with a reduction in height, primarily dissipating heat on the preform surface. Total energy dissipation, die load, and frictional energy notably increase with die speed, particularly with higher bulging coefficients and initial relative densities. Additionally, inertial energy dissipation rises rapidly under these conditions. The intricate relationship between fractional internal energy dissipation and fractional frictional energy dissipation to total energy dissipation highlights the complexity of the process, with internal energy dissipation decreasing while the frictional energy dissipation component increases with bulging coefficient and relative density. At high die velocities, most energy dissipates as frictional heat, underscoring the need to control forging velocity for desired product outcomes.

In order to fabricate homogeneous large-scale Ti-5Al-5V-5Mo-3Cr (Ti-5553) alloy bulk with fine and equiaxial β grain, we performed a series of multi-axial α + β field forging with 62 forging cycles on the large-scale Ti-5553 billet by using 12.5 MN high-speed hydraulic press. The β-annealed microstructure was the starting microstructure of the billet. After the 6th forging cycle, β grain deformed dramatically, and the grain-boundary network developed within the irregular β grain. As the forging cycle increased to 44, the volume fraction of the fine and equiaxial β grain that is less than 20 μm, which is caused by dynamic recrystallization, increased gradually. However, the incomplete dynamic recrystallization region within the original β grain could not be eliminated. As the forging cycle further increased, the volume fraction of the fine and equiaxial β grain did not increase. In contrast, the abnormal grain growth of the β phase occurred during 50th~62nd forging cycle. Here, we attribute the formation of the incomplete dynamic recrystallization region and the abnormal grain growth of the β phase to the high deformation rate of the α + β forging. The refining behavior of β grain and the abnormal coursing β grain, which is found during the multi-cycle multi-axial forging of large-scale Ti-5553 alloy billet, are seldom reported in the isothermal compression of small-scale Ti-5553 alloy specimen. The findings of the paper are instructive for improving the sub-transus forging strategy that is used to fabricate the large-scale homogeneity Ti-5553 alloy billet with fine and equiaxial β grain.

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To address the difficulty of directly detecting internal stresses in high-temperature forgings during dual-manipulator control experiments and the significant safety risks associated with high-temperature environments, this study developed an experimental device to simulate the deformation behavior of such forgings. First, numerical simulations of the elongation process were conducted using DEFORM V11 software to examine the deformation mechanisms of high-temperature forgings. Quantitative results for axial deformation, maximum deformation velocity, and deformation force ranges were obtained, which defined the operational specifications and functional requirements of the device. Second, the mechanical structure and hydraulic system were designed based on engineering principles. The dynamic response characteristics of the simulation device under conventional PID and fuzzy PID control were compared through simulations, and the feasibility of the fuzzy PID control strategy was experimentally verified. Finally, a joint simulation model of the high-temperature forging deformation simulation device and the dual forging manipulator clamping system was established. This model was used to analyze the dynamic response of the simulated workpiece under typical cooperative conditions of dual manipulators and to assess the accuracy of the simulation process during clamping. The results confirmed the practical applicability of the device. Overall, the developed simulation device can effectively reproduce the deformation behavior of high-temperature forgings under ambient conditions, providing a safe and reliable platform for studying coordinated control strategies of dual forging manipulators.

Abstract In gravity drop hammer forging, the ram is lifted to a certain height and then released. During the downward motion, the hammer is accelerated by gravity and strikes the workpiece. The operational environment of these machines presents adverse conditions, such as extreme temperatures, high impact velocity, and intense energy generation. These aspects make the instrumentation of these machines highly challenging, leading to the use of theoretical models to describe their dynamic behavior. However, these models involve simplifications that reduce the accuracy of the analyses. This study aims to evaluate the efficiency of Digital Image Correlation (DIC) as a monitoring tool for the hot forging process of AA 6351 aluminum alloy using a drop hammer. Digital Image Correlation allows for the quantitative analysis of the evolution of the workpiece deformation during the process, providing valuable data on process and machine performance. The results obtained demonstrate that Digital Image Correlation is a promising approach for monitoring the hot forging process with a drop hammer, with the potential to enhance the quality of the final product and process efficiency.

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The study reports on the metal flow behaviour during upsetting or forging using the finite element method. Forging simulation studied the metal flow behaviour of a laboratory-sized specimen and a cylindrical engine connecting rod specimen of AISI 52100 high-chromium steel specified in the software database. The focus was to study the effect of deformation conditions (temperature and die velocity) on metal flow behaviour during forging. The simulation results showed heterogeneous metal flow behaviour during forging. Hence, this indicates that effective flow stress and flow strain, particle flow velocity, effective strain rate, damage and temperature distribution exhibited inhomogeneous deformation behaviour. As the temperature increased, the forging load decreased, thus a decrease in deformation resistance. The simulation of the engine connecting rod further confirmed inhomogeneous deformation during forging. Damage coefficient results show that the crack pin end had a higher damage probability during forging. This study clearly showed that finite element simulation can predict metal flow behaviour during the forging of AISI 52100 steel. The study output provides a basis for analysing and optimising most industrial metal forming processes using a numerical simulation approach. Hence, this method is effective in predicting flow behaviour.

Abstract The primary function of the dual forging manipulators’ walking system is to precisely control the axial feeding of forgings. The stability and control accuracy of this system significantly impact forging quality and production efficiency. To achieve synchronized position control, a mathematical model was developed using two 20 kN forging manipulators as the research subjects. Subsequently, a triangular velocity trajectory planner was devised to examine the effects of acceleration, start–stop coefficient, and peak coefficient on the control behavior of the system. Lastly, the efficacy of this control method, which employing triangular velocity planning (TVP) for displacement–velocity composite control, was confirmed through equivalent experiments. The results indicate that this method can effectively regulate the response dynamics of two walking systems, with a displacement difference of less than 1 mm between the two manipulators.

The effect of adiabatic heating on microstructure evolution during high strain rate subtransus forging of a Ti-6Al-4V alloy having equiaxed initial microstructure was studied through experiments and modelling. Ø45 × 67.5 mm cylindrical billets with embedded thermocouples were forged at four different α+β temperatures on a Schuler 2100t screw press to evaluate the extent of adiabatic heating in different parts of the billet. In the centre of the billet, the highest temperature increase due to adiabatic heating exceeded the β transus (~1000 °C) during forging. The microstructure of the forged billets was examined for any changes in β phase volume fraction due to adiabatic heating. The forging process was then simulated in Deform 2D/3D software. High strain rate compression testing in the α+β and β temperature fields was carried out using a Phoenix forge simulator to generate input mechanical properties for the model. The effect of the billet size on the α-β phase transformation during forging and post-forge cooling is also discussed.

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To explore new approaches to severe plastic deformation and the ductility of a multicomponent magnesium–lithium alloy, an ultralight microduplex Mg-9.55Li-2.92Al-0.027Y-0.026Mn alloy was made by novel multidirectional forging and asymmetrical rolling, and the superplasticity behavior was investigated by optical microscope, hot tensile test, and modeling. The average grain size is 1.9 μm in this alloy after multidirectional forging and asymmetrical rolling. Remarkable grain refinement caused by such a forming, which turns the as-cast grain size of 144.68 μm into the as-rolled grain size of 1.9 μm, is achieved. The elongation to failure of 228.05% is obtained at 523 K and 1 × 10−2 s−1, which demonstrates the high strain rate quasi-superplasticity. The maximum elongation to failure of 287.12% was achieved in this alloy at 573 K and 5 × 10−4 s−1. It was found that strain-induced grain coarsening at 523 K is much weaker than the strain-induced grain coarsening at 573 K. Thus, the ductility of 228.05% is suitable for application in high strain rate superplastic forming. The stress exponent of 3 and the average activation energy for deformation of 50.06 kJ/mol indicate that the rate-controlling deformation mechanism is dislocation-glide controlled by pipe diffusion.

High strain rate biaxial forging (HSRBF) was performed on AZ31 magnesium alloy to an accumulated strain of ΣΔε = 1.32, the related microstructure, texture and mechanical properties were investigated. It was found that the microstructure evolution can be divided into two steps during HSRBF. In the early forging processes, the refinement of the grain is obvious, the size of ~10 μm can be achieved; this can be attributed to the unique mechanisms including the formation of high density twins ({101¯2} extension twin and {101¯1}-{101¯2} secondary twin) and subsequently twining induced DRX (dynamic recrystallization). The thermal activated temperature increases with the increase of accumulated strain and results in the grain growth. Rolling texture is the main texture in the high strain rate biaxial forged (HSRBFed) alloys, the intensity of which decreases with the accumulated strain. Moreover, the basal pole rotates towards the direction of forging direction (FD) after each forging pass, and a basal texture with basal pole inclining at 15–20° from the rolling direction (RD) is formed in the full recrystallized HSRBFed alloys. The grain refinement and tiled texture are attributed to the excellent strength and ductility of HSRMBFed alloys with full recrystallized structure. As the accumulated strain is ΣΔε = 0.88, the HSRMBFed alloy displays an outstanding combination of mechanical properties, the ultimate tensile strength (UTS) is 331.2 MPa and the elongation is 25.1%.

No abstract available

Mechanical characterisation of metallic materials at intermediate strain rates is essential to calibrate and validate computational models for industrial applications such as high-speed forming processes i.e. hammer forging, blanking, forming, etc. The most common devices that perform medium to high loading rate experiments are the servo-hydraulic universal testing machines and Split Hopkinson bar systems. Here we analyse the possibility of employing an in-house designed and constructed DirectImpact Drop Hammer (DIDH) for material mechanical characterisation at medium strain rates, ranging from 100 to 300 s-1. To show the suitability of the DIDH for mechanical characterisation, uniaxial compression experiments on S235JR structural steel are conducted and compared with finite element (FE) simulations performed with an elasticthermoviscoplastic material model previously calibrated with Split Hopkinson Pressure Bar (SHPB) tests.

A practical methodology is presented to characterize the thermoviscoplastic flow stress at larger strain over the temperature range of cold metal forming using tensile and compression tests. Its importance is emphasized for non-isothermal finite element (FE) analysis of automatic multi-stage cold forging (AMSCF) process where maximum strain and strain rate exceed around 3.0 and 200/s, respectively. The experimental compressive flow stress is first characterized using traditional bilinear C-m model with high accuracy. It is employed for describing the closed-form function model to extrapolate the experimental flow stress over the experimentally uncovered ranges of state variables. The strain effect on the flow stress is then improved using the experimental tensile flow stress accurately calculated at large strain and room temperature. A complicated flow behavior of S25C characterized by its dynamic strain aging features is expressed by the presented methodology, which is utilized to analyze the test upsetting and AMSCF processes by the elasto-thermoviscoplastic finite element method for revealing the effects of flow stresses on the process.

The present investigation focuses on the implementation of the multi-axial forging process, recognized as a severe plastic deformation (SPD) technique, with the aim of elevating the mechanical features of the widely employed Al 6061 alloy. Specifically utilized in the automotive and aviation industries, this alloy's behavior was meticulously examined through a series of quasi-static and dynamic tests. To achieve this objective, the multi-directional forging (MDF) process was implemented for up to three cycles, involving a total of nine passes, at a raised temperature of 200 °C. Subsequently, the severely deformed material underwent utilizing high strain rate loading for the Split Hopkinson Pressure Bar (SHPB) test system. After MDF, the grain size is refined down to below 11 microns with a starting grain size of 13 microns. This is reflected as increased hardness and yield strength in the quasi-static regime. For SHPB characterization, increased dynamic strength is also observed. However, although the yield strength showed about 60% increase with decent ductility, the maximum dynamic strength increased about 10% after SPD with a relatively brittle behavior.

The constitutive model is widely employed to characterize the rheological properties of metallic materials under high-temperature conditions. It is typically derived from a series of high-temperature tests conducted at varying deformation temperatures, strain rates, and strains, including hot stretching, hot compression, separated Hopkinson pressure bar testing, and hot torsion. The original experimental data used for establishing the constitutive model serves as the foundation for developing phenomenological models such as Arrhenius and Johnson–Cook models, as well as physical-based models like Zerilli–Armstrong or machine learning-based constitutive models. The resulting constitutive equations are integrated into finite element analysis software such as Abaqus, Ansys, and Deform to create custom programs that predict the distributions of stress, strain rate, and temperature in materials during processes such as cutting, stamping, forging, and others. By adhering to these methodologies, we can optimize parameters related to metal processing technology; this helps to prevent forming defects while minimizing the waste of consumables and reducing costs. This study provides a comprehensive overview of commonly utilized experimental equipment and methods for developing constitutive models. It discusses various types of constitutive models along with their modifications and applications. Additionally, it reviews recent research advancements in this field while anticipating future trends concerning the development of constitutive models for high-temperature deformation processes involving metallic materials.

Magnesium alloys are highly strain rate sensitive and exhibit good workability in a narrow forging temperature range. Consequently, parts made of these materials are usually forged with low-speed hydraulic presses, using specially designed tool heating systems in order to ensure near-isothermal conditions. This study investigates whether popular magnesium alloys such as Mg-Al-Zn can be forged in forging machines equipped with high-speed forming tools. Experimental upset forging tests on AZ31B, AZ61A and AZ80A specimens were conducted, using a screw press with a ram speed of 0.5 m/s and a die forging hammer with a ram speed at stroke of about 5 m/s. Test specimens were preheated to 350 °C, 410 °C and 450 °C. After the upset forging process, they were air- or water-cooled and then examined for their workability, hardness and grain size. To validate the results, a forging process for a producing handle was designed and modelled by the finite element method. Distributions of strain, temperature and fracture criterion were analysed, and energy and force parameters of the forging process were calculated. After that, experimental tests were performed on AZ31B and AZ61A specimens in order to determine mechanical properties of forged parts and examine their micro- and macrostructure. Results have demonstrated that AZ80A is not suitable for forging with either the screw press or the die forging hammer, that AZ61A can be press- and hammer-forged but to a limited extent, and that AZ31B can be subjected to forging in both forging machines analysed in the study.

Hot deformation behavior of 4130 steel and optimization of its processing parameters are presented in this paper. Compression tests were performed at temperatures ranging from 800 to 1200 °C and at the strain rates in the range from 0.01 to 100 s−1. A comprehensive analysis of the material behavior at different temperature and strain-rate ranges was performed taking into account various criteria of stability and instability of the material flow under various thermomechanical conditions. The flow–stress curves obtained during compression tests, as well as the processing maps elaborated on the basis of various flow–stability criteria, are discussed. Processing parameters developed according to the Prasad’s and Murty’s criteria are recommended for designing the technology of forging of the investigated steel. Such parameters ensure the homogeneity and stability of the material flow in a forged part, what was confirmed by successful forging of 4130 steel in industrial conditions. The processing map developed according to Gegel’s approach, as compared to the processing maps obtained in accordance with the Prasad’s and Murty’s criteria, should be treated as general support for determining the thermomechanical processing parameters.

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Microstructure control, especially the elimination of microtexture in Ti alloys such as Ti-6Al-4V and TIMETAL 834, is important to improve the fatigue life. In most research, small samples measuring 8–10 mm in diameter and 12–15 mm in height are utilized. However, the cooling rates of these small samples are always quite rapid, whereas the cooling rates of larger engine components, are relatively slow. Therefore, in this study, microstructural change involving different thermomechanical processing (TMP) was investigated using large TIMETAL 834 samples of 80 mm in diameter and 100 mm in height. The samples were forged at 940 and 1000 °C using a 1500 t forging simulator and heat treated at 900 and 1000 °C. Our goal is to attain a macroscopic understanding that connects the processing, microstructure, and fatigue life. The significant microstructure difference is that the deformed microstructure remains in the small sample due to rapid cooling, while the formation of a bimodal structure or an α phase globularization progressed in the large samples by diffusion during slow cooling. Improvement in the fatigue life was obtained by the 85% forging at 1000 °C. This is due to the refinement of the α grains and active slip in microtexture by alignment of the c-axis of α grains far from the tensile axis.

Ti-6Al-4V warm forged fasteners are a critical part of the aerospace industry, as they are used in vast quantities for mechanical joining of components for the fuselage, wing-skin and aero-engine. These components are produced in vast quantities at rapid production rates through multi-blow axial forging However the rate that they are manufactured means that manufacturers rely upon periodic part conformance testing to understand if the part is within tolerance or if any undesirable manufacturing defects such as cracks or underfilling are present. Thus, a right-first-time manufacturing approach is essential to minimize non-conformant scrap. An analysis of the Ti-6Al-4V supplied raw material for axial forging, in a variety of different bar diameter sizes and from different industrial suppliers, was conducted. This was to attempt to understand whether material property variation or operator variation was the root cause for some material behaving differently during the manufacture route. Experimental testing was performed through microstructure characterization and mechanical testing methods. The volume fraction of the β-phase was noted to be marginally higher in material with good forgeability. The hardness of the inner core of the bar appears to be a critical material property for the Ti-6Al4V bar, with an overly hard bar-core hindering forgeability of the bar. This is believed to be due to the hotter central region malleability being key for forgeability. Micro-void porosity was also noted which could lead to stress concentration locations, or crack initiation, and as such is a deleterious property for forgeability. The experienced forgeability of the Ti-6Al-4V bars have been demonstrated to be sensitive to rather small variation in measured microstructure and mechanical property. It is believed that cumulative impacts of small differences, 1% variation in α-phase volume fraction, small variations in elongation to failure, 1% variation in elastic modulus and microhardness profile variation at the center of the bar of less than 10 HV0.3, can combine to significantly impact the forgeability of Ti-6Al-4V bar.

Rapid‐solidified Al–Zn–Mg–Cu alloys possess widespread application prospects owing to their excellent properties, particularly high specific strength. Nevertheless, their further development for use as advanced structural parts is significantly limited by their intrinsic porosity. Herein, the flow stress subroutine and micropore evolution model are combined to predict the cracking and damage behavior of a rapidly solidified Al–Zn–Mg–Cu disk‐shaped part during hot forging. The results reveal that the damage to the part during plastic forming is inversely proportional to the relative density. Reasonable matching between the height‐to‐diameter ratio (H/D) and the initial relative density is the key factor in avoiding cracking and damage to the part. The closure sequence of the micropores is from the center to the outside of the billet. A billet with an H/D of 1 and initial relative density of 0.95 can reach full density after forming, and a damage‐free part can be obtained. These simulation results are verified by analyzing the microstructural characteristics and mechanical properties of the actual forged part.

Specific experimental tests with loadings conditions close to those of industrial fast forming processes as rapid forging, rapid stamping or high speed machining, characterized by large plastic strains, localized deformations and important gradients of strain rates, strain and temperature, requires to analyses material flow behavior at different initial temperatures. One of the more important conditions to obtain intrinsic rheological constitutive equations is to have a quasi-homogenous initial temperature distribution and especially to keep constant the material microstructure during the specimens heating. The rapid induction heating seems to be one of the most reliable processes. This scientific study proposes an inverse analysis technique based on numerical finite element modelling to define on the thermal point of view, optimal specimen shapes for performing hot rapid crushing tests from homogenous initial temperature field.

The Ti-6242 titanium alloy samples were forged at 1020 °C (slightly above the β-transus) and subjected to ultra-short isothermal holding (0–320 s) prior to quenching to investigate the rapid microstructural evolution in the parent β phase. Electron backscatter diffraction (EBSD) with parent β-phase reconstruction reveals that within only 1–3 s of holding, a pronounced <111> fiber texture develops along the forging axis, superseding the original <100> deformation fiber. This ultrafast texture change is attributed to metadynamic recrystallization (MDRX)—the post-deformation growth of nuclei formed during dynamic deformation. The newly formed <111>-oriented β grains still contain residual substructure, indicating incomplete strain release consistent with MDRX. Longer holds (tens of seconds) lead to more extensive static recrystallization and normal grain growth, which dilute the strong <111> fiber as grains of other orientations form and coarsen. These findings demonstrate that even a brief pause after forging can markedly alter the prior β texture via a MDRX mechanism. This insight highlights a novel approach to microtexture control in Ti-6242: by leveraging MDRX during short holds, one can potentially disrupt the formation of aligned α colony microtextured regions (MTRs, or “macrozones”) upon subsequent cooling, thereby mitigating dwell-fatigue susceptibility. The study revises the interpretation of the recrystallization mechanism in short-term holds and provides guidance for optimizing β-phase processing to improve fatigue performance.

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction techniques, such as impulse and explosive compaction, aim to achieve higher powder density without requiring sintering, further improving PM efficiency. Among these techniques, magnetic pulse compaction (MPC) has gained notable interest due to its unique process mechanics and distinct advantages. MPC utilizes the rapid discharge of energy stored in capacitors to generate a pulsed electromagnetic field, which accelerates a tool to compress the powder. This high-speed process is particularly well-suited for compacting complex geometries and finds extensive application in industries such as powder metallurgy, welding, die forging, and advanced material manufacturing. This paper provides an overview of recent advancements and applications of MPC technology, highlighting its capabilities and potential for broader integration into modern manufacturing processes.

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High-strength materials are pressure-treated under isothermal conditions with heating using a hydraulic forging equipment. At the same time, along with strainer- hardening, the workpiece material exhibits viscous properties, i.e. it is viscoplastic. This factor must be taken into account when developing pressing technology, since the power modes of stamping and the maximum possibilities of shaping depend significantly on the speed of the operation. A yield with heating of a ring blank under viscoplastic conditions is viewed. The relations for calculating the force and deformation modes of a ring blank yield under the axial symmetry scheme are proposed. The energy method of balancing the capacities of internal and external forces was used to calculate the power regime. Coulomb's law of friction is adopted on both: tool contact surfaces and the ring blank. The internal force capacities were calculated in the deformation block and on the fracture surfaces of the displacement velocities in accordance with the selected kinematically possible velocity field, including the friction surfaces. The optimization of the velocity field was carried out according to the principle of minimum operating pressure. The assessment of the damage to the material of the blank is carried out according to the energy and deformation criteria of destruction. The calculated results of the yield force and material damage for high-strength aluminum and titanium alloys are presented. It is shown that under isothermal yield of a ring blank, the force decreases at low operating speeds. The damage rate of a number of materials, the behavior of which is described by the energy theory of destruction, decreases with a decrease in the speed of the operation. For materials subject to the deformation theory of fracture, the rate of deformation has no effect on damage, but is determined only by the degree of deformation.

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As a critical component for motion control in heavy machinery, high-speed hydraulic actuators require effective buffering to mitigate end-impact. This paper proposes a compact buffering cylinder with a multi-orifice sleeve. A theoretical model was established to derive the throttling area profile for constant deceleration. A detailed numerical simulation model was then developed, and the key orifice parameters (diameter and spacing) were optimized using a Particle Swarm Optimization (PSO) algorithm to maximize buffering efficiency and smoothness. A prototype based on the optimal design was manufactured and tested dynamically. Experimental results demonstrate that the buffer smoothly arrested a piston with an initial velocity of 8 m/s and a moving mass of 80 kg within a 250 mm stroke. The optimized design achieved a 14% increase in buffering efficiency and reductions in peak force and pressure compared to the initial design, validating the proposed optimization methodology and providing a reliable solution for high-speed actuator protection.

The paper presents a study on speed control of hydraulic linear actuators without servo valves. A typical hydraulic circuit, including a cylinder, a set of four throttle valves, and four high-frequency directional control valves, is implemented. The characteristics of components are mathematically modeled and numerically investigated in MATLAB/Simulink. The research exploited a combination of rule-based control algorithm and pulse-width modulation for oil flow rate control, thereby controlling the piston speed. The control process is carried out in two stages. In the first stage, the rule-based control algorithm makes piston speed track the set value with rough error. Pulse-width modulation is then applied to a certain high-frequency valve to help the speed closely match the desired value in the second stage. The obtained simulation results show that speed tracking control is guaranteed. Thus, the advantages of pulse-width modulation control are not only promoted, but the pulse regulation frequency for high-speed on/off valve is also significantly reduced. The control method can be considered as an effective solution for controlling accurately the speed of the hydraulic systems instead of using servo valves.

As a control structure, the magnetic repulsion device is applied in the high-speed switch hydraulic operating mechanism. It must not only move quickly but also stop precisely. The repulsion disk is subjected to high impact loads, resulting in the phenomenon of fracture and damage. In this paper, the magnetic repulsion value of the engineering prototype was obtained through simulation. A super-elastic material was selected as the buffer, and impact dynamics simulation was carried out. A double-repulsion-disk structure was designed, which reduced the structural impact stress and satisfied the operation time of less than 2 milliseconds. This realized redundant design and improved the reliability of the high-speed switch hydraulic operating mechanism, which is of great significance for the safe operation of high-speed switches.

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The hypereutectic alloy Al-8Ca-2Mn-1Ni-0.3Fe-0.3Zr (wt. %), obtained by casting in an electromagnetic crystallizer, was subjected to hot rotational forging from an initial diameter of 14.5 mm to a final diameter of 5.2 mm. It was found that rotational forging led to the formation of an ultrafine grain-subgrain microstructure. After forging, the alloy has a yield strength, tensile strength and elongation of 269 MPa, 342 MPa and 4.5%, respectively, with a fully viscous fracture and a low thermal coefficient of linear expansion at the level of standard eutectic silumins.

A comprehensive topology performance diagram of the permanent magnet vernier machine is constructed in this paper. The changes in the air gap harmonic magnetic field and the contribution of each harmonic to the average torque of the permanent magnet vernier machine (PWVM) with integer slot distribution winding and fractional slot concentrated winding are studied. Additionally, in the key electromagnetic performance indicators, such as copper loss, iron loss, efficiency, and power factor of different machines are analyzed and summarized. After comprehensive consideration, the optimal design scheme is identified, and the geometric parameters of the machine are optimized using a global optimization method. Subsequently, a prototype is manufactured employing a modular stator structure, and bench experiments are conducted. The experimental results demonstrate a close agreement with the finite element analysis results, providing crucial technical reference for the design of forging servo machines. It is noteworthy that the machine topology has been accepted by Estun Ltd for potential future industry applications.

Recently, the application of aluminum based on ultra-high strength steel is expanding around high-end models of electric vehicles, so it is necessary to develop strategic welding/joining technologies for these materials. In the case of overseas advanced automobile companies, such development is being carried out at the level of introducing mass production facilities through the development of joining technology, but in Korea, the localization rate of original core technology and related equipment in the field of welding and joining is still very insufficient. Therefore, in this study, in order to develop a high-strength rivet suitable for the rivet process during the multi-material bonding process, cold forging steel was used to attain an appropriate level of hardness through changes in the microstructure through heat treatment. Rivets with different hardness were fabricated through heat treatment, and flaring and tensile test were conducted. As a result of flaring test of rivets, buckling occurred with hardness values of Hv 447 and 486, while cracks occurred without buckling in rivets with hardness values of Hv 506. But as a result of tensile shear test using GA980 and Al5052 materials, there was no significant difference in tensile shear load values according to hardness values of the rivets.

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AC servo press has the advantages of high productivity, high flexibility, high precision, energy saving and environmental protection, and is the first choice for advanced forging and forming equipment. This paper intends to design and analyze a permanent magnet synchronous motor (PMSM) for servo press, which can meet the performance requirements of maximum torque, low moment of inertia and high efficiency heat dissipation. The finite element model(FEM) is established to study the electromagnetic field, stress field and temperature field of motor. The results show that the electromagnetic design of the motor meets the driving requirements of the servo press. The punching design reduces the rotor weight by 28.05%, and the structural strength of the rotor can ensure the safe and stable operation. Under the condition of high power-density and intermittent operation, the motor temperature rise is within the allowable range, and the motor operating temperature can be reduced by $13^{\circ}\mathrm{C}$ under the condition of independent fan forced air cooling.

Increasing in the efficiency and expanding the technological capabilities of the main technological equipment of forging and stamping production will significantly increase the output of modern machine-building enterprises. It is shown that increasing in the equipment productivity is achieved as a result of analyzing the structure of mechanisms with the introduction of a new structure, which will increase the speed of lifting the slider on the upward stroke and productivity by up to 20 % compared to traditional schemes of the main actuators. The complication of the structure also leads to an expansion of the technological capabilities of the press when achieving its minimum overall dimensions.

The possibility of transferring the production process of forged stampings made of heat-resistant nickel from a hammer 16 tons falling parts mass hammer to 13 tons falling parts mass hammer is considered. It is established that without adjusting of the technology and configuration of the final shape of the stamping, the mechanical properties of the products are reduced. The ways to adapt the technological process of discs stamping made of EP693-VD alloy to falling parts lower mass hammer of without loss of mechanical properties.

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Abstract This work concerns the analysis of the application of the nitriding process to forging dies used for the production of automative forgings on a hammer. The subject technological process concerns the production of forgings of a ring section made of AISI 304 stainless steel. The subject process is carried out on a LASCO HOU-160 forging hammer with a power of 16 kJ, in two operations, on the blocking impression and then on the finishing impression. In order to assess the influence of the nitriding process on the durability of tools, operational tests are carried out for three sets of tools after thermochemical treatment under real industrial conditions and then confronted with the results for standard tools (without a nitrided layer). The comprehensive studies carried out, including macroscopic analyses combined with scanning, numerical modeling, and microstructural tests for both standard tools and after nitriding, show a decrease in the durability of forging tools as a result of the use of nitriding in relation to the previous technology. It should also be considered that the process was carried out on hammers, for very thin forgings. Then, there are very high dynamic loads, which can lead to cracking of hard nitriding layers.

The study refers to the application of numerical modeling for the improvement of the currently realized precision forging technology performed on a hammer to produce connecting rod forgings in a triple system through the development of an additional rolling pass to be used before the roughing operation as well as preparation of the charge to be held by the robot’s grippers in order to implement future process robotization. The studies included an analysis of the present forging technology together with the dimension–shape requirements for the forgings, which constituted the basis for the construction and development of a thermo-mechanical numerical model as well as the design of the tool construction with the consideration of the additional rolling pass with the use of the calculation package Forge 3.0 NxT. The following stage of research was the realization of multi-variant numerical simulations of the newly developed forging process with the consideration of robotization, as a result of which the following were obtained: proper filling of the tool impressions (including the roller’s impression) by the deformed material, the temperature distributions for the forging and the tools as well as plastic deformations (considering the thermally activated phenomena), changes in the grain size as well as the forging force and energy courses. The obtained results were verified under industrial conditions and correlated with respect to the forgings obtained in the technology applied so far. The achieved results of technological tests confirmed that the changes introduced into the tool construction and the preform geometry reduced the diameter, and thus also the volume, of the charge as well as provided a possibility of implementing robotization and automatization of the forging process in the future. The obtained results showed that the introduction of an additional rolling blank resulted in a reduction in forging forces and energy by 30% while reducing the hammer blow by one. Attempts to implement robotization into the process were successful and did not adversely affect the geometry or quality of forgings, increasing production efficiency.

Abstract The relationship between the microstructure of the ring forging and the ultrasonic anomalies were studied in response to the localized anomaly observed during the non-destructive testing of TA15 titanium alloy ring forging. The distribution of internal defects was explored through water immersion ultrasonic testing of ring forging. The microstructure of the normal region and the abnormal zone were compared using scanning electron microscopy and electron backscatter diffraction techniques. And finite-element simulation was used to simulate the formation process of the abnormal ultrasound position. The results showed that the different layers of the ring-forged component exhibited varying degrees of bottom wave attenuation along the radial direction. The abnormal area corresponded to a higher number of primary α-phase and larger grain sizes. Under the combined effect of temperature and stress, the recrystallized grains began to grow abnormally, leading to significant bottom wave attenuation.

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