International Journal of Material Forming最新文献

To effectively predict the deformation behavior of AZ31B magnesium alloy (Mg alloy) in plastic forming assisted by pulse current, the influences of different pulse currents’ frequencies on the flow stress of Mg alloy were studied. The Voce and Hockett-Sherby constitutive models were modified to include the influence of frequencies, and the parameters of the constitutive models were calibrated based on the experimental data. The Cazacu 2004 yield criterion was improved to describe the yield behavior under the action of pulse current, in which the tensile-compressive asymmetry keeps changing with the increase of plastic strain. The three-point bending tests of AZ31B Mg alloy assisted by different frequency pulse currents were carried out. The improved constitutive model and yield criterion were embedded in ABAQUS using user material subroutine VUMAT for the corresponding three-point bending simulation. It is found that the improved constitutive model and yield criterion considering the current frequencies and tensile-compressive asymmetry can obviously improve the simulation accuracy.

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This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are critically evaluated. Various cleaning methods, including centrifugation, ultrasonic solvent washing, extraction, and distillation are compared based on their ability to remove residual cutting fluids. Cold compaction, which augments chip density to approximately 2.5 g/cm³, significantly curtails oxidation losses and enhances metal recovery. During remelting, NaCl-KCl-based fluxes with limited fluoride additions (e.g., 3–7 wt% Na₃AlF₆) disrupt oxide networks but require careful dosage control to minimize furnace corrosion and environmental hazards. Moreover, mechanical stirring combined with suitable melting temperatures reduces porosity while enhancing melt purity. Future research should prioritize the development of low-energy cleaning methods, flux composition optimization, and scalable production techniques to further advance sustainable aluminium recycling.

The single-stage light gas gun has been employed to drive the T2 copper welding on Q235 carbon steel. The effect of the Zn interlayer on the microstructure at the interface of impact welded the T2 copper/Q235 carbon steel composite has been studied by both experiment and numerical simulation. The simulation results are mainly consistent with the results of the experiment. The 100 µm Zn interlayer can broaden the lower limit of the T2/Q235 weld window, resulting in a 3.11% reduction in energy dissipation during the impact welding. While the 25 µm Zn interlayer achieves a reduction of up to 11.6%. As the thickness of the Zn interlayer diminishes, the plastic strain, pressure, and temperature of the flyer plate gradually increase, allowing for the modulation of welding parameters through varying Zn interlayer thicknesses.

The coarse columnar crystals and inter-dendritic Laves phases of laser deposition manufactured (LDM) GH4169 are the two the primary reasons for the undesirable strength and plasticity compatibility and anisotropy of the alloy. In this study, we used friction stir processing (FSP) on LDMed GH4169 samples, the microstructure difference between the FSP zone and the LDM zone were compared, the microstructure refinement process in the FSP zone were analyzed, and the mechanism of microstructure refinement and its influence on the properties of the room-temperature tensile properties were proposed. The results show that fine equiaxed grains with an average grain size of ~ 3.13 μm were obtained in the stir zone (SZ) due to intense plastic deformation and recrystallization processes.The size and shape of the Laves phase changed significantly after FSP, the Laves phase fragmented in the thermo-mechanically affected zone (TMAZ), distributed in long strips along the rotational direction of the tool, and distributed as small particles in the SZ; while the MC-type carbides precipitation exhibited no significant change.The strength and plasticity of the FSP samples were significantly improved relative to the LDM samples, the yield strength and tensile strength reached 546 MPa and 1063 MPa, respectively, and the elongation reached 43%. Numerous strengthening mechanisms to increase the yield strength of the materials are analyzed and calculated in detail.

Developing and optimizing manufacturing processes for composite components is commonly supported by finite element (FE) simulations. Initial concepts are modeled and parametric studies are conducted to determine optimum process parameters. Built-in application programming interfaces (APIs) typically allow for a script-based automation of systematic model modifications for many FE solvers. However, the evaluation of simulation results typically depends on a manual inspection by experts, despite its repetitive nature. This study aims to use APIs to develop a fully-automated method for identifying and evaluating critical features and thus, the quality of draping simulations. The focus thereby lies on providing a validated framework for the automated evaluation of draping simulation results, rather than claiming perfect virtual representation of experimental draping. Three different metrics (deviations of fiber angles, the boundary contour and topological defects) are used to determine the overall draping quality of simulation results. With the developed routine, all quality metrics can be estimated quite well for simulation results. The routine is designed to be extended for the use with experimental data for a reliable real-life quality assessment.

Formability is the ability of a material to undergo plastic deformation without being damaged. In sheet metal forming, materials are known to experience deformation in biaxial stretch mode. In order to simulate the common failure strains in sheet metal forming process, numerous formability test methods can be used. A material’s formability can be altered in several ways, one of which is post-weld heat treatment. In this study, the effect of post-weld heat treatment on the formability of aluminum alloy 6061 and SAE1020 mild steel tailor welded blanks fabricated by friction stir welding was evaluated using limiting dome height test. It was found that the specimens which underwent post-weld heat treatment recorded a lower springback and higher value of plane strain, indicating a better formability. The improved formability is attributed to microstructural homogenization, defects elimination, residual stresses relieve and IMC layer growth control from the post-weld heat treatment process.

The objective of the paper is to analyze the fundamental influence of the tool design on the in-plane torsion test in order to create a common basis for carrying out tests that enable the characterization of comparable material parameters between various test setups. The clamps have a major influence on the process limits wrinkling and slippage of the in-plane torsion test. The size and the surface structure of the clamping on the process limit of slipping and wrinkling is investigated. Results show that a ring-shaped clamping surface can transmit up to 50% more torque at the same clamping force compared to a full-circle clamping surface. Investigations show that torque transmission through plain clamping surfaces is not possible for thin sheets (t = 0.5 to 3.0 mm). In order to enable torque transmission in spite of this, the structuring of the clamping surface is necessary. Therefore, radial serrations are well suited, to ensure a homogenous torque transmission over the circumference. An analytical approach was developed and numerically validated, that can determine the indentation depth, the maximum transmittable torque and the necessary clamping force for radial serrations. The geometrical and material specific influence on the process boundary of wrinkling was analyzed and a material independent recommendation for the geometrical shape of the clamps was proposed. This publication is an extended version of the paper “In-Plane Torsion Test—Analysis of the Tool Design”, which was published in the Proceedings of the 14th International Conference on the Technology of Plasticity—Current Trends in the Technology of Plasticity (ISBN 978–3-031–41022-2).

The demand for bent hollow parts, particularly those with larger diameters and smaller bending radii, has significantly increased in industries such as automotive, energy, and aerospace. However, manufacturing these components presents substantial challenges, primarily due to the risk of defects such as wrinkling or cracking caused by excessive wall thinning. This study investigates the combined manufacturing process of Rotary Draw Tube Bending (RDTB) followed by Tube Hydroforming (THF) to address these challenges. Through numerical simulations and experimental validation, the process parameters of both forming techniques, as well as key defects including wrinkling, wall thickness reduction, and die filling rate, were thoroughly examined. The findings reveal that excessive thinning in the extrados during RDTB is mitigated during the subsequent THF operation. Similarly, excessive thickening in the intrados during RDTB is counteracted by the stretching and thinning effects of THF. The results demonstrate that the proposed process, with optimized parameters, enables the production of high-quality elbow parts, confirming the method's effectiveness and its potential as a reliable manufacturing solution for complex elbow geometries.

In the dynamic forming process of profile during roll bending, the downward pressure parameters at different times exert a nonlinear coupled effect on the final curvature radius, making it difficult to predict the ultimate curvature radius accurately. This has become a challenging issue in the field of industrial precision forming. To address this problem, a CNN-TCN-TPA neural network model is proposed to model the complex coupled relationships during the dynamic roll bending forming process. Firstly, a multi-scale CNN is employed to extract the implicit features of roll bending at different time scales, enabling the model to understand the inherent patterns of roll bending data comprehensively. Subsequently, TCN is utilized to learn the influence relationships before and after roll bending forming. Finally, a temporal attention mechanism is adopted to learn the impact of different historical moments on the final outcome, thereby establishing the CNN-TCN-TPA roll bending forming curvature radius prediction model and achieving accurate prediction of the roll bending forming curvature radius. The prediction performance of the CNN-TCN-TPA model is compared with traditional neural network models, TCN models, and TCN-TPA models. The results indicate that the CNN-TCN-TPA model exhibits higher prediction performance compared to other neural network models, with mean square error and mean absolute error of 5971.65 and 24.42, respectively.

Pin structures extruded from the sheet metal plane have numerous industrial applications. For instance, they can be used in bulk microforming to solve handling difficulties or in joining technology to connect dissimilar materials to overcome challenges of different chemical, thermal and mechanical properties of materials. Due to the absence of material flow restrictions in the direction of the sheet metal plane, pin extrusion is affected by numerous process-, workpiece- and tool-related parameters, which have a huge impact on the material utilization and the obtainable pin geometry. Within the scope of this study, a combined numerical-experimental research approach is used to analyze the influence of the material and its condition on the achievable pin height and the occurrence of the mostly undesired funnel formation at high punch penetration depths. For this purpose, elastic-ideal plastic and elastic-real hardening model materials are first investigated numerically, which are subsequently validated and verified in experiments by using the materials Cu-OFE and DC04 on a laboratory scale. Based on the results, recommendations for the material selection and its properties are derived in order to maximize the material utilization. In addition, a pin joining process with locally modified extrusion conditions to increase the load-bearing capacity, especially under axial load, is being investigated with DP600 and AA 6014-T4. This process is a new type of two-stage mechanical joining process without an auxiliary joining element in which pin structures extruded from the sheet metal plane are used to join dissimilar materials in a subsequent step. In this work, test specimens are locally pre-punched before pin extrusion to create an enhanced pin geometry in order to achieve an improved undercut in the subsequent joining process. As a result, a new type of pin geometry was realized and investigated, which shows a significant increase of up to 82% in load-bearing capacity under axial load compared to the existing reference pin geometry.