1,720,998 research outputs found
Numerical, experimental, and analytical investigation of the skin contamination evolution in the extrusion of different industrial profiles
No full textIn the context of aluminum alloy extrusion, the presence of the skin contamination defect imposes the scrap of the contaminated profile length due to its lower mechanical properties. For understanding the evolution of the defect, comprehensive analyses, either experimental investigations or reliance on predictive techniques, are mandatory. Recently, numerical methods have gained interest in predicting the development of skin contamination, although their level of accuracy remains uncertain. This research focuses on a detailed experimental and numerical analysis of three different AA6XXX industrial extruded profiles. The aim is to compare the evolution of the skin contamination experimentally observed with the outcomes of the simulation using the commercial finite element code Qform Extrusion UK. The main findings of the analysis confirmed the potentiality and the accuracy of the numerical tools, also evidencing the current limitations of the empirical and analytical industrial practices
Experimental Investigation and Finite Element Simulation of the Microstructural Evolution in AA6082 Friction Stir Welded Joints
No full textPhase Field Method for the Assessment of the New-Old Billet Material Interaction during Continuous Extrusion Using COMSOL Multiphysics
No full textFinite element modeling of microstructure evolution and bonding during friction stir extrusion of AA6061 powder at different tool feed rates and rotational speeds
No full textPredicting grain size in extruded AA6063 profiles: A unified approach based on finite element analysis and machine learning
Full text linkThe evolution of grain size in AA6XXX extruded profiles is a critical factor for enhancing mechanical, thermal and surface properties. Traditional methods for microstructure control rely on extensive experiments requiring significant time and resources. To address this issue, the present work proposes a method for microstructure prediction combining numerical data from Finite Element Method (FEM) simulations with experimentally acquired microstructure data to train an Artificial Neural Network (ANN) capable of predicting grain size. Data was acquired for three distinct AA6063 aluminum alloy profiles extruded under various process conditions in terms of profile and tool geometry, ram speed, billet pre-heating temperature and extrusion ratio, representing a diverse and heterogenous dataset comprising grain size (55-228 mu m), strain (2.8-28), maximum strain rate (2-190 s-1), exit temperature (480-580 degrees C), Zener-Hollomon parameter (4 x 1015-4 x 1017) and Stored Energy (170-480 kJ/mol*K) for training and testing different ANN configurations. The final trained ANN was able to accurately predict grain size in regions of normal grain growth but was less reliable at foreseeing formation of the largest and smallest grains due to limited data points within this range. A Mean Absolute Percentage Error (MAPE) of 13.9% was achieved for predictions in the test set with an ANN comprising two fully connected layers with 9 and 19 neurons, respectively, Rectified linear unit (ReLU) activation functions and a ridge L2 penalty term of 10-6 for regularization. The presented methodology provides a foundation for the development of new data-driven approaches aimed at facilitating microstructure prediction in industrial settings
Charge weld evolution in hollow aluminum extrusion: Experiments and modeling
Full text linkCharge welds occur in billet-to-billet extrusion processes due to the transition between successive billets. The material in this transition zone is typically characterized by substandard mechanical properties. In industrial practice, a specified length of the extruded profile is cut away and recycled as in-process scrap. Therefore, understanding the extrusion mechanisms affecting the properties of the charge weld is crucial to controlling product quality, reducing non-conformities and improving the extrusion yield. This paper provides new insights into thermo-mechanical mechanisms associated with charge weld of circular aluminum tubes. A large number of carefully-controlled, full-scale extrusion experiments were conducted in an industrial environment to research charge weld evolution mechanisms and influential parameters. In addition, a finite element (FE) model was developed to predict the charge weld evolution across the cross section and along the profile. The experimental and numerical results show good agreement in terms of the location of the charge weld within the extruded profile. Moreover, a comparison with analytical models in the literature reveals that the FE model provides a significantly more accurate prediction of the length of the extruded profile affected by the charge weld (‘scrap length’). Based on the validated FE model, a sensitivity study was done to explore the effect of process parameters on charge weld evolution, particularly focusing on material flow and dead metal zone. The results show that the ram speed influences the charge weld evolution, while changes in billet temperature are insignificant. In conclusion, the findings presented in this study provide new insights that serve as practical guidance to the mechanism of charge weld evolution. They also highlight the applicability and limitations of numerical and analytical methods in assessing industrial extrusion problems.publishedVersio
Experimental investigation and numerical prediction of the peripheral coarse grain (PCG) evolution during the extrusion of different AA6082 aluminum alloy profiles
No full textExtrusion of Light and Ultralight Alloys with Liquid Nitrogen Conformal Cooled Dies: Process Analysis and Simulation
No full textThe die cooling by means of liquid nitrogen is a widely adopted industrial practice used to increase theproduction rate in the hot extrusion process of light alloys. The development of a reliable numerical modelable to simulate the cooling channel efficiency has become of primary interest for the extrusion sector inorder to avoid ineffective die cooling and time-consuming trials and errors. In this work, H13 die insertswith a helicoidally conformal channel were designed and printed by means of the SLM additive technology.Billets of AA6063 aluminum and ZM21 magnesium alloys were extruded at different process speeds undermonitored conditions to verify the insert resistance and the cooling effectiveness. A 3D finite element modelof the extrusion process coupled with a 1D model of the cooling channel was generated within the COMSOLsimulation environment. The experimental outputs were also used to validate the numerical predictions ofthe developed simulations. The FEM results showed a good matching with the loads and temperaturesobtained in the experimental trials. Moreover, the endurance of the AM tool validated the prediction of thestress field, thus proving the reliability of the numerical model for the application in the extrusion of lightalloys sector
A simple approach to transient-state modeling of nitrogen cooling in the extrusion of light-alloy complex profiles
No full textNitrogen cooling has become a popular solution to reduce heat flux between the die and the profile in the hot extrusion process. However, designing effective cooling channels for complex-shape profiles poses challenges, especially when the phase transition of nitrogen significantly impacts heat transfer with solid bodies. To this end, the ability to model both the liquid and the gas phase is instrumental in devising design strategies, yet it should be combined with low computational complexity for industrial applications. The present work is aimed at employing the homogenous-flow approach as a simple, yet representative methodology to consider both phases in the simulations. One-dimensional model of nitrogen was combined with a three-dimensional extrusion model to perform the transient analysis of the whole process, mostly focused on the transition from fully gaseous to fully liquid flow. Validation using extrusion tests on seventeen AA6060 billets demonstrates the model's predictability in comparison with a fully liquid model. The average error associated with Homogeneous Flow Model was evaluated as below 10%, whereas the fully liquid approach yielded 25%. That proved the ability of the proposed model to reproduce the cooling effect, thus supporting the design of the cooling subsystem within the context of the whole extrusion tooling
Assessment of the Optimization Strategy for Nitrogen Cooling Channel Design in Extrusion Dies
Full text linkAluminum extrusion is an efficient industrial process. However, one of the main problems is related to the temperatures developed during the process that can detrimentally affect the achievable productivity, profile quality and/or die life. Cooling of the die with liquid nitrogen represents an efficient solution to overcome this limit but a further issue arises lying in the number of process and design variables that need to be managed in order to set-up of an efficient system. In this context, a 3D FE model of the extrusion process, coupled with a 1D model of the cooling channel, previously proposed by the authors, has been integrated in an optimization platform in order to iteratively and automatically adjusts the channel geometry and the process variables gaining to a final optimal solution in terms of thermal balance, cooling efficiency and nitrogen consumption. The original channel design used during the extrusion of industrial hollow AA6060 profile guaranteed an efficient but unbalanced cooling with a maximum temperature deviation of 60 °C registered by the thermocouple positioned around the bearings. The optimized designs showed temperature deviations below the 16 °C as well as the reduction of 50% in terms of nitrogen consuming.</jats:p
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