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Static recovery was confirmed to be the dominant softening mechanism during annealing for the studied A5083 aluminum alloy. The kinetics of static recovery, described based on the activation parameters (activation energy and volume of static recovery) and the static softening fraction, were mainly studied through two thermomechanical tests, namely, double-pass compression and stress relaxation tests. A new approach was proposed to measure the static softening fraction in the stress relaxation test. In general, a higher temperature or strain rate accelerates static recovery, while interestingly, the effect of pre-strain on static recovery is opposite in cases with and without external stress, owing to the enhanced static recovery by external stress during annealing. In addition, microhardness tests and electron backscatter diffraction (EBSD) characterization were also conducted to verify the accuracy of the results. The grain average misorientation approach based on EBSD characterization was confirmed to be effective in distinguishing and quantifying static recovery. It is noteworthy that the special stress hardening phenomenon occurring at 400 °C and 0.1/s is caused by strain aging, showing the complexity of the material behaviors after deformation of the studied aluminum alloy.

In this paper, the fundamental microstructure evolution of M2 high speed steel was investigated during semi-solid controlled cooling and conventional cooling, respectively. Semi-solid controlled cooling was conducted at 1260 °C with cooling rates from 0.1 to 10 °C/s, while conventional cooling was conducted at 1200 °C and 890 °C with different cooling rates. The continuous cooling transformation curves were plot according to the microstructure evolution. The results showed that microstructure transformation behavior of cooling structure in semi-solid temperature range was different from that of conventional process. For semi-solid specimen, the solid austenite dissolved more alloy elements, and the austenite stability was increased. The solid matrix was pearlite structure in the samples with cooling rate of 0.1 °C /s. When the cooling rate reached 1 °C/s, the granular pearlite disappeared and martensite lath was formed. The structure was relatively uniform, on which there were large carbide with regular shape. The solidified liquid phase showed a network shape surrounding the solid particles. The size of solid particles showed a decreasing trend with the increase of cooling rates. For conventional cooling process, the large eutectic M6C carbide and the small precipitated MC carbide could not be dissolved by austenitized at 890 °C. Increasing the austenitization temperature helped dissolving part of the carbides. The hardenability of M2 steel was high. The hardness has increased to a high level for both semi-solid and conventional specimens when cooling rate reached 1 °C/s. No obvious increase happened when cooling rate continued increasing.

Although recent developments in 3D printing technology have made it possible to fabricate metamaterials with characteristic mechanical properties, it is not easy to fabricate complex shapes containing cavities. In this study, a composite structure comprising two types of materials without a cavity was optimized. Moreover, a mechanical metamaterial with a negative Poisson's ratio that can be fabricated using an additive manufacturing method was developed. First, a homogenization method that characterizes the properties of composite structures was briefly described. Then, an optimization problem to realize a negative Poisson's ratio was formulated, and a level set-based topology optimization method was proposed to solve the abovementioned problem. Next, three-dimensional numerical examples are presented to confirm the effectiveness of the proposed method, and the deformation behaviors of the optimized designs are numerically examined. Furthermore, a sample containing the optimized design with negative Poisson's ratio for the tensile test was fabricated using a 3D printer. We conducted some experiments to evaluate its mechanical performance., Comment: 26 pages, 14 figures

In the last few decades, metal-based composites and related manufacturing methods have attained a significant research attention thanks to the possibilities they offer to tailor both the material properties and the part in-service performances. A variety of metal-based composite parts is available for commercial applications since more affordable and robust manufacturing processes and quality control techniques have recently overcome many challenging technological issues. The paper aims at describing the forming processes applied to metal-based composites, with particular emphasis on the process features, part obtainable characteristics, and modelling issues for a convincing design and optimization of the process itself. The most recent progresses and challenges are illustrated in detail, including innovative materials and processes that are emerging to answer the requirements of advanced engineering applications as well as new modelling techniques and current approaches to face economic and environmental issues.

The integration of topology optimization with lattice structures has shown great potential for the additive manufacturing (AM) of lightweight structures with superior mechanical properties and multifunctional characteristics. To further improve the design manufacturability, structural efficiency, structural isotropy and computational efficiency, the homogenization-based topology optimization (HMTO) method was proposed to integrate with plate–lattices exhibiting superior mechanical properties and excellent elastic isotropy. The validity of the proposed method was demonstrated by comparing the optimized models with conventional models composed of truss–lattices and solid materials. Results show that the proposed method highly improves stiffness and energy absorption capability.

Ultra-lightweight sheets with excellent deformability are required for the development of new air vehicles, as well as greener conventional vehicles. Carbon fiber reinforced plastic (CFRP) has a high specific rigidity and strength but is too expensive to be used in general machine parts. Using CFRP enhances the properties of the material itself. Furthermore, developing the usage of the material also makes the mechanical properties higher. The purpose of this paper is to combine both methods and produce a material with better rigidity and deformability. The new structure was proposed considering the moment of inertia of area. This structure was excellent not only in terms of rigidity but also in the moldability of the core. In addition, the effects of the structure dimensions on the moldability, bonding strength and flexural rigidity were determined using finite element (FE) analysis and experiments. By comparing the results of the FE analysis conducted under pure bending conditions with three-point bending experiment, it was found that the FE analysis of pure bending fails to predict the three-point bending stiffness because the shear stress has a significant effect on the experimental measurements. By modifying the model from pure bending to three-point bending, the experimental results were well reproduced by the 3D FE analysis.

Cold rolling is widely employed in the manufacturing industry for the production of metal plates. In the cold rolling process, the thickness reduction of the metal plate under the recrystallization temperature generates severe anisotropy, this influences the subsequent forming processes. Therefore, the generation and prediction of metal plate anisotropy during cold rolling is a highly interesting research topic involving upstream studies of sheet metal forming. In this study, using the finite element method with zooming analysis, we established an efficient elastic–plastic analysis method to predict the metal plate texture after cold rolling. This method for cold rolling texture prediction was confirmed by comparing the experimental and simulation results of cold rolling for an S45C plate with a body-centered cubic lattice. Further, the numerical analysis method proposed in this study can contribute to the study of anisotropy as an alternative to experimental approaches.

The purpose of this study is to obtain a constitutive equation of high-accuracy flow stress in superalloy 718, which allows fabrication of highly reliable disks for gas turbine engines. Hot compression tests using superalloy 718 at deformation temperatures from 850 to 1100 °C, a 67% height reduction, and strain rates of 1, 10, and 25 s−1 were performed to investigate the flow stress behavior, which excludes environmental effects during hot working by inverse analysis. The effects of dynamic recrystallization and strain-induced dynamic precipitation on the flow stress were also investigated. The dynamically precipitated δ phases deformed at 1050 °C and γ″ phases deformed at 950 °C might affect the increase in the plastic modulus F1 and the decrease in the critical strain εc, deteriorating the accuracy of regression in terms of, for example, the strain rate sensitivity m and the temperature sensitivity A. A constitutive equation for a generalized flow curve for superalloy 718 is proposed by considering these effects.

The present study is aimed at fabricating Cu/Al/Cu tri-layered clad composite with one pass heavy reduction roll bonding and subsequent heat treatment. High strength clad composite was designed via introducing 7075 alloy. The interface bonding mechanism was discussed under different conditions. The mechanical properties of the Cu/Al/Cu clad composites were also studied. The results showed that thick interfacial intermetallic layer could be formed after certain heat treatments (annealing at 500 °C or T6 treatment). The peeling behavior was affected by the intermetallic layer. The interfacial bonding behavior was related with the state of Cu/Al/Cu clad composite. Peel strength could reach 78.1 or 62.2 N/cm after annealing at 500 °C or T6 treatment, respectively. Lamellar delamination traces were remained on the peel surface after peel process. The thickness of interfacial compounds was in proportional with the altitude of delamination remaining. During the peel process, peel gap sheared through the interfacial layer and transformed between two matrix layers periodically. The mechanical properties of present clad composite could reach a best comprehensive value after T6 treatment with strength of 458 MPa and elongation of 15.2%. The strength level increased clearly as compared with pure aluminum and copper “sandwich” clad composite.

Residual stresses in metallic components greatly affect the geometrical accuracy of advanced high-strength steels (AHSS) products used for automotive industry. Chain-die forming is a promising method to fabricate AHSS products which can minimize the residual stress induced. This paper aims to understand the residual stress in chain-die-formed dual-phase (DP) steels through analytical and numerical modelling together with experimental validation. Analytical and numerical models were firstly employed to predict the stress development and associated residual stresses induced by chain-die forming in consideration of an as-received residual stress field and a comprehensive material-hardening model. The residual stresses in different regions of formed parts were practically measured using the neutron diffraction method to verify the developed models. Same as the mesh size of the examining points of finite element analysis (FEA) models, the averaged over the same sampling size is measured to guarantee the accuracy. It seems to be consistent with the simulation and experimental results in consideration of both factors. However, compared with as-received residual stress, the kinematic factor has a more dominating impact on the final residual stress. The results presented should contribute to the prediction of geometric errors and minimize product defects caused by the residual stresses in chain-die forming or equivalent sheet metal-forming industry.

Given the increasing use of glass mat-reinforced thermoplastic (GMT) composites, the formability of GMT sheets is currently a topic of research. A new sheet forming process for solidified GMT was developed. In this process, a GMT sheet was sandwiched by dummy metallic sheets during deep drawing. The dummy metallic sheets acted as protective materials and media for heating the GMT sheet. In this study, tensile tests of GMT specimens were carried out under different temperature conditions. The effect of temperature on the tensile deformation was analyzed. The effect of temperature on the deep drawing process of GMT sheets with dummy sheets was further investigated. Finite element method (FEM) was conducted to simulate the deep drawing process. In the drawing force rising stage, the law of drawing force with the depth of the drawing was analyzed using FEM and experiments.

In this study, an anisotropic constitutive model based on the non-associated flow rule was developed for anisotropic sheet metals. This model was defined in the quadratic form of the Hill’s anisotropic function under a general three-dimensional stress condition. The anisotropic parameters for the yield function were identified using the directional planar yield stresses, bulge yield stress and shear yield stress, while those for the plastic potential function were identified using the directional r-values. A full expression related to the non-associated flow rule was applied and the model was implemented into the finite element code ABAQUS. A static-implicit analysis and the solid element were applied. Capability of the developed model for predicting the anisotropic behavior of sheet metal was investigated by considering two different sheet metal forming processes: cylindrical cup drawing of AA2090-T3, A6061P-T6 and SPCE; and hole expansion forming test of A6016-O. Cup heights and through-thickness strain distributions obtained from the simulations were compared with the experimental data. Results demonstrate that the developed material model considering 3D condition can improve accuracy of predicting the anisotropic behaviors. Furthermore, the simple formulations are efficient and user-friendly for computational analyses and solving the common industrial sheet metal forming problems.

Thixoforging experiments on SiC particles (SiCp) reinforced AZ91 magnesium (Mg) matrix composites (AZ91-SiCp) were conducted under different forging temperatures and forging loads. The microstructures and mechanical properties of the thixoforged AZ91-SiCp samples were investigated experimentally by microstructural analyses, hardness tests, tensile tests, and compression tests. AZ91-SiCp semisolid slurries exhibited different forming behaviors at different temperatures, because the different volume fractions and morphologies of the liquid phase, SiCp, and α-Mg in them at different temperatures. The outflow of the liquid phase not only inhibited crack formation on the surface of the thixoforged samples but also resulted in segregations of intermetallic compounds and SiCp in the thixoforged samples. Mechanical properties of the thixoforged samples affected significantly by the volume fraction and distribution of brittle Mg17Al12 intermetallic compounds surrounding α-Mg and SiCp transformed from liquid phase during cooling. Higher forging temperatures improved the outflow of the liquid phase during thixoforging and resulted in thixoforged samples more inhomogeneous distributions of microstructures and mechanical properties. Forging load did not significantly affect the outflow of the liquid phase during thixoforging or the inhomogeneity of the microstructure of thixoforged samples. Higher forging loads caused higher residual stresses in the bottom regions of the thixoforged samples, which resulted in higher values of hardness in these regions.

To comply with increasingly stringent exhaust-emission- and fuel-consumption-legislation imposed on internal-combustion-engine-powered vehicles; and to realise the widespread deployment of electric vehicles hindered by heavy energy storage systems, lightweight construction achieved through application of fibre reinforced polymers, most notably Carbon Fibre Reinforced Polymer, to the mass-produced automotive architecture has been predicted to increase in the coming years. However, this is difficult to envisage by the time-, labour-, energy- and waste-intensive part-manufacturing processes of present, including autoclave-processing and Out-of-Autoclave processes such as Resin Transfer Moulding. In this paper, an innovative concept Out-of-Autoclave process, based on the Prepreg Compression Moulding process, in which hot forming and curing of reinforced thermoset composite prepreg are integrated in one step, previously demonstrated to offer potential for reduced cycle-time, lead-time and financial cost; and greater environmental sustainability compared to current processes, was evaluated for manufacturing Carbon Fibre Reinforced Polymer automotive parts. Formability, springback, geometric accuracy and mechanical properties of parts were determined by macroscopic observation, scanning electron microscopy, flexural testing, tensile testing and fatigue testing. Springback-free parts exhibiting mechanical properties within approximately 80 % of benchmark autoclave-produced parts were produced. Compressive crash-box testing was then conducted across strain-rates of 0.02, 0.20 and 2.00 s-1, with crushed-length, specific energy-absorption and crush-force-efficiency superior to autoclave-produced parts. The concept process thus demonstrated a significant step towards realising the application of Carbon Fibre Reinforced Polymer to the mass-produced automotive architecture and to an array of applications including tensile and flexural strength-critical safety-cell body-parts, impact-energy-absorptive-critical crumple-zone body-parts and fatigue-critical suspension-parts.

Modelling of metal forming processes is an essential task of production engineering. Due to the latest technological developments, a huge variety of models is already available and extending continuously. Thus, it is important to find a suitable model. This paper gives an overview on the common classification and characterization of modelling and models in metal forming, as well as introduces a model selection procedure. Based on this classification, various relevant process limits for metal forming are investigated regarding existing models. The conclusion of the paper shows open topics as well as upcoming challenges in modelling process limits in metal forming.

Forming is widely used due to its high efficiency in material utilization and its high production rate in general. Most forming processes control the geometry of final products through a set of tooling. The increasing demands on lightweight products have challenged the performances and functionalities of tooling. This paper provides a systematic review of recent advancements related to tooling performance and functionalities, including tool materials, tooling fabrication processes (e.g., machining, heat treatment, coating, surface texturing, and additive manufacturing), sensing, and data analytics. Finally, recommendations on future research directions for metal forming tooling are provided.

A kind of 9Cr18Mo multidiameter shaft part was fabricated through a designed thixoforging set-up. As compared with conventional heat treatment specimen, wear and corrosion behavior of 9Cr18Mo thixoforging specimen were studied. The results showed the surface of 9Cr18Mo thixoforging specimen demonstrated fine wear and corrosion resistance. Thixoforging specimen exhibited functionally graded property with inner austenite particles and fine dendrite eutectic skin layer. At the skin layer, the former solidified liquid led to the concentration of alloying elements such as Cr and Mo. Besides, eutectic structure of secondary austenite and M7C3carbide helped to improve the hardness. The high hardness of M7C3carbide and high concentration of Cr, Mo elements at the edge skin layer contributed to reducing the delamination wear, abrasive wear and the appearance of oxidation. Even at higher wear load, relative sliding occurred at the wear surface, which avoided crack formation and chunk spalling. As compared with conventional heat treatment specimen, corrosion current density of thixoforging surface reduced, while corrosion potential increased. Thixoforging surface also exhibited passivation behavior and the corrosion resistance increased slightly. High concentration of Cr and Mo at the skin layer avoided the formation of chromium depleted zone. In view that wear and corrosion failure tend to occur at the surface of specimen, the thixoforging specimen with a wear and corrosion skin layer might provide a possibility for expanding the application fields of 9Cr18Mo steel.

Sandwich structures have had remarkable success in engineering applications, but their applications are mostly limited to flat panel types because of their poor formability. To expand the range of applications of sandwich structures, new formable CFRTP (carbon fibre reinforced thermoplastic) core sandwich sheets are proposed, where a truncated dome core structure is designed to increase formability and structural performance. This paper first introduces the design methods followed by the fabrication processes and finally reports the flexural properties and formability of the proposed core sandwich sheets. Fabricated sandwich sheets were successfully subjected to hat bending without failure.

A new steel chemical composition is combined with a new press hardening process, in which die-quenching is interrupted by opening the forming tool to permit slow cooling of the hot formed part through the anisothermal bainitic ferrite transformation. This promotes carbon partitioning to austenite before the forming tool is re-closed and die-quenching is resumed to near-ambient temperature. The final microstructure is predominantly bainitic ferrite with dispersions of martensite and up to 11 % retained austenite. Retained austenite can undergo stress induced transformation to martensite in an automobile crash event. The steel exhibits up to 25 % elongation and 930 MPa tensile strength. In contrast to traditional cold formable Transformation Induced Plasticity assisted steels, where retained austenite is consumed during work hardening of cold forming, here, the desired microstructure is achieved after hot forming meaning the retained austenite is more uniformly distributed within the formed part, which enhances energy absorption. The new steel chemical composition is carefully designed to provide optimal microstructural evolution within the constraints of the new press hardening process, yet relatively lean and manufacturer friendly. The new press hardening process is energy efficient as secondary heating is not required since retarded cooling through the bainitic ferrite transformation is provided by residual heat accumulation of the newly developed titanium alloy forming tool. Development of the new technology is demonstrated by press hardening experiments, tensile testing, microstructural analysis, transversal & axial crush testing of formed parts and numerical simulation of crush testing, including a new modelling technique that more accurately simulates deformation of hot versus cold formed parts. Results show a 22 % increase to energy absorption under axial crushing compared to traditional cold formed Transformation Induced Plasticity assisted steels owing to greater work hardening capacity in formed radii of the part, which are shown to be exposed to the highest stresses during crushing.

To study the dynamic softening behaviors of 5083 aluminum alloys with different initial microstructures under hot compression, hot compression tests of extruded and homogenized specimens were conducted at a strain rate ranging from 0.1 to 10/s and deformation temperatures ranging from 350 to 450 °C. The obtained true stress–strain curves of homogenized specimens were lower than those of extruded specimens especially at the initial deformation stage, suggesting that the effect of different initial microstructures on flow stress is significant especially at the initial deformation stage. Electron backscatter diffraction (EBSD) was used to observe the microstructure evolution process. The characteristics of continuous dynamic recrystallization, particle-stimulated recrystallization, and discontinuous dynamic recrystallization were confirmed. The experiments deformed at the same temperature and strain rate but with different strains showed the transition from continuous to discontinuous recrystallization. The recrystallization mechanism of 5083 aluminum alloys with different initial microstructures is thus finally illustrated.

A process–microstructure–property database on forging and heat treatment of superalloy 720Li was established by high precision large-scale 1500 ton forging simulator and laboratory-scale forging simulator. The database was utilized to determine the parameters of flow stress, microstructure, and strength prediction models. The models were integrated to CAE software to predict process–microstructure–property relationships. In the integrated model, the stress, strain, and temperature distributions and their temporal development are calculated by using flow stress model and thermophysical properties. The calculated stress, strain, and temperature data are inputted into the microstructure model. The microstructure model considers grain growth, recrystallization, and precipitation of γ′ and calculates the temporal evolution of microstructural features. The strength model considers solution, grain boundary, and precipitation strengthening and calculates high-temperature 0.2% tensile proof stress, which is related to creep and low-cycle fatigue properties, from the calculated microstructural features. The integrated model successfully predicted the load, microstructure, and strength distribution of a prototype forging experiment conducted by the Hitachi Metals 6000 ton forging machine. The integrated model is a promising tool to design the forging and heat treatment process of the alloy.

For the purpose of obtaining a niobium-microalloyed steel with a preferable ultrafine-grained ferrite microstructure, a thermomechanical controlled processing (TMCP) strategy that included a hot shear deformation conducted near the local phase transformation temperature and a subsequent cooling process is proposed. As a large plastic strain was enforced by the simple hot shear deformation, severe plastic deformation (SPD) of the niobium-microalloyed steel was realized. The proposed TMCP strategy was simulated physically on a Thermecmastor-Z compression machine combined with a multi-type cooling system. Various cooling rates of different cooling methods resulted in reconstructive and displacive phase transformations from γ-Fe to α-Fe and led to different microstructural morphologies. In addition to phase transformations, the precipitation of carbides, grain growth, plastic deformation, discontinuous dynamic recrystallization (dDRX) of retained austenite grains, and continuous dynamic recrystallization (cDRX) of ferrite grains occurred during hot shear and subsequent cooling. The effects of the strain rate and forming temperature on the microstructural and textural evolution of niobium-microalloyed steel during hot shear and subsequent cooling were investigated and discussed. A niobium-microalloyed steel with a homogenous ultrafine-grained ferrite microstructure and intense γ-fiber texture was fabricated when the forming temperature, strain rate of hot shear deformation, and cooling rate of subsequent mist cooling were 1073 K, 20 s−1, and 10 K·s-1, respectively.

To improve structural performance, bendability and potential functionality of metal-based sandwich sheets, the 3D lattice cores were sandwiched between thin metallic face sheets. The bending properties of sandwich sheets with 3D printed carbon fiber reinforced plastic (CFRP) lattice cores originating from basic topologies of spherical shell, tetrahedral truss and tetrahedral plate were systematically investigated. The effects of core topologies, core relative densities, core heights, face sheet thicknesses on structural properties were clarified. The common failure modes during bending of sandwich sheets, such as face buckling and shear failure of core, were deeply investigated by theoretical models and experimental tests. At a prescribed radius of 60 mm, the sandwich sheets with the bilayered dome, octet truss and plate lattice cores of relative density of 50 %, height of 6 mm and face sheet thickness of 0.5 mm are bendable. This study demonstrates the feasibility of design and production of bendable sandwich sheets with 3D lattice cores based on the theoretical and experimental validations. The designed bendable sandwich sheets can be adopted to replace conventional heavy monolithic metal sheets in various engineering applications, which is anticipated to fulfill the high demand for lightweight functional materials.

To further understand metadynamic recrystallization, various measurement techniques were performed with two materials: SUS316 austenitic steel and A5083 aluminum alloy, which were selected to represent materials with low to medium and high stacking fault energies, respectively. Microstructure characterization using electron backscatter diffraction with the grain orientation spread approach was utilized as a direct measurement technique to study metadynamic recrystallization. Additionally, indirect measurement techniques, including double-pass compression, stress relaxation, and microhardness tests, were conducted. A new approach, including its simplified version, is proposed to determine the recrystallized fraction from the stress relaxation test, which is effective even in the case of incomplete recrystallization. A comparison between various approaches for determining the recrystallized fraction shows their advantages and disadvantages. A further understanding of the metadynamic recrystallization is achieved. First, with careful setup of water cooling, unlike the conventional understanding that metadynamic recrystallization does not require an incubation time, the incubation time is approximately 1 s in both materials and can be reduced to 0 s at high temperatures in SUS316. Second, the retardation effect of external stress on recrystallization in both materials is different because on the one hand recovery competes with recrystallization, while on the other hand recovery promotes the nucleation of recrystallization.

A series of reheating-isothermal holding experiments and compression tests were conducted on pristine magnesium alloy AZ91 extruded by equal channel angular extrusion (ECAE) and SiC particles (a volume fraction of 15%) reinforced AZ91 composite (AZ91-SiCp) by regular extrusion. Dissolution of eutectic compounds and partial melting of the α-Mg matrix occurred during the reheating of these materials. Spherical semisolid slurries of these materials were obtained when the reheating temperature and isothermal holding time were 550 °C and 20 s, respectively. The presence of SiCp in AZ91-SiCp not only caused lower liquid fractions of semisolid slurries but also resulted in higher values of flow stress during semisolid compression tests. Both AZ91 alloy and AZ91-SiCp composite exhibited better thixoforming properties at high temperatures. Segregation of SiCp did not occur during thixoforming of AZ91-SiCp composite after an isothermal holding at semisolid temperatures for 20 s.

The deformation behavior and microstructure evolution of extruded A5083 aluminum alloy were studied by performing hot compression tests at deformation temperatures ranging from 350 °C to 500 °C and strain rates ranging from 0.01 s−1 to 50 s−1. Inverse analysis was used to reduce the effects of inhomogeneous distributions of deformation and temperature on the flow curves. On the basis of the obtained flow curves, a set of constitutive equations was modeled to describe the deformation behaviors, and these equations can be regarded as the “material genome” as they provide a fundamental understanding of material behaviors during deformation. A model was developed to predict the flow stress under the entire range of experimental conditions. Error analysis verified the reliability of the model and confirmed it to be effective in predicting the flow stress. Microstructure observations confirmed dynamic recrystallization occurred. Besides, particle-stimulated nucleation was also observed, verifying that large particles can promote dynamic recrystallization. The effects of temperature and strain rate on microstructure evolution were analyzed. The relations between deformation behavior, microstructure and mechanical property were also discussed, the good correlation shows a possibility of controlling microstructure and mechanical property by selecting suitable forming parameters.

Punching is an efficient and economical process for producing a hole in structures for functional requirements, repair, maintenance, and so forth. Toward extending the use of punching to new materials, the punching of multilayer CFRP laminates and CFRP/metal hybrid composites was investigated. In this paper, the effect of the unidirectional (UD) prepreg size on the shear behavior of pseudo-ductile CFRP laminates and CFRP/metal hybrid composites is discussed on the basis of experimental observations. CFRP laminates were individually fabricated using standard (149 g/m 2 ) and thin-ply (62 g/m 2 ) prepregs, and were bonded with three metals (aluminum alloy A6061, magnesium alloy AZ31, and advanced high-strength steel SPFC980) by utilizing an autoclave (co-curing) and adhesive glue for hybrid composite application , then punched by a circular die and punch tool at room temperature. The effects of the UD prepreg size on the punch force, punching resistance (Ks), quality, and sheared surfaces of the through-holes are discussed. The shear behavior for punching in different composites was also studied by microscopic examination. Our results are expected to enable quantitative design for the development of punched CFRP laminates and CFRP/metal hybrid composites.

In typical resin molding, multi-cavity molds are generally used to reduce cycle time and increase productivity. However, these types of molds are large, which also increase the size of the facility. The newly developed compact multi-station resin molding machine features single-cavity molds and split process which are conducted in parallel in four stations to cut down on cycle time. To realize this method, small molds with self-clamping is required. This paper reports the results of the method for obtaining the optimum conditions for suppressing the generation of flashes and the degradation of dimensional accuracy in a short time using CAE.