Fabrication and characterization of zeolite coatings on aluminum and magnesium alloys

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Finite Element Modeling of Microstructural Changes in Turning of AA7075-T651 Alloy and Validation

The surface characteristics of a machined product strongly influence its functional performance. During machining, the grain size of the surface is frequently modified, thus the properties of the machined surface are different to that of the original bulk material. These changes must be taken into account when modeling the surface integrity effects resulting from machining. In the present work, grain size changes induced during turning of AA 7075-T651 (160 HV) alloy are modeled using the Finite Element (FE) method and a user subroutine is implemented in the FE code to describe the microstructural change and to simulate the dynamic recrystallization, with the consequent formation of new grains. In particular, a procedure utilizing the Zener-Hollomon and Hall-Petch equations is implemented in the user subroutine to predict the evolution of the material grain size and the surface hardness when varying the cutting speeds (180 - 720 m/min) and tool nose radii (0.4 - 1.2 mm). All simulations were performed for dry cutting conditions using uncoated carbide tools. The effectiveness of the proposed FE model was demonstrated through its capability to predict grain size evolution and hardness modification from the bulk material to machined surface. The model is validated by comparing the predicted results with those experimentally observed

experimental and numerical analysis of roller burnishing of waspaloy

Abstract Nickel based superalloys, such as Waspaloy , are extensively used for applications under heavy environmental conditions due to their superior thermo-mechanical properties. However, manufacturing processes of these materials are challenging since they involve issues related to their poor workability. Thus, huge research work for optimizing the processing parameters is still required. This problem becomes even more pronounced when finishing processes, such as roller burnishing, are considered. In fact, it is crucial to use parameters able to increase the productivity and to improve the quality of the manufactured parts, consequently a huge number of preliminary experimental tests have to be carried out. Hence, numerical simulation can be a valid support for obtaining information about the metallurgical phenomena that affect the materials while large strains occur. However, commercial software are not still able to appropriately predict such modifications. Thus, the main objective of the present work is to study a roller burnishing on Waspaloy in terms of processing parameters and surface integrity by experimental and numerical analysis, in terms of forces, temperatures, roughness, microstructural modification and microhardness. Thus, the customized simulation demonstrated to provide useful information able to drastically reduce the number of needed tests leading also to a deeper knowledge of the microscopic phenomena involved in the process

A physically based model of Ti6Al4V turning process to predict surface integrity improvements

Abstract In turning processes, surface improvements are strictly related to the physical phenomena induced by the involved thermo-mechanical loads. These phenomena are difficult to be analyzed while they occur, therefore the process simulation is a very important tool to deeply understand their evolution. Turning experiments were carried out on Ti6Al4V workpiece under different machining conditions. The microstructural modifications were analyzed in terms of metallurgical changes and micro-hardness. The physical mechanisms that occurred on the machined surface were investigated to construct a constitutive material flow model. The developed material model was implemented via sub-routine in a commercial FE software and validated through comparisons with experimental data (cutting forces, temperatures and microstructural modifications). The model was employed to predict the process variables of scientific interest (microstructural changes and surface improvement). The numerical results in main cutting forces, feed forces and temperatures prediction proved the accuracy and reliability of the proposed numerical model showing a good agreement with the experimental data

Functionalized additively manufactured parts for the manufacturing of the future

Abstract Innovation technology is giving the opportunity to fabricate products and parts in alternative ways and with special characteristics, which do not strictly depend on the primary manufacturing process. In particular, smart manufacturing seeks for flexible systems and customizable products, recognizing additive manufacturing (AM) processes as a key element. To successfully integrate AM into the production chain it is necessary to overcome its limitations in terms of final product quality and reliability, wisely choosing post-processing operations. This work outlines how it is possible to significantly improve AM product performance using an environment friendly process, such as burnishing, coupled with a numerical simulation model encouraging customer integration and developing a flexible manufacturing process capable to conform with the main idea behind Industry 4.0

A Physically Based Model to Predict Microstructural Modifications in Inconel 718 High Speed Machining

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Burnishing of AM materials to obtain high performance part surfaces

Purpose: This paper aims to provide a flexible solution to include additive manufacturing into a process chain complying with Industry 4.0 pillars, overcoming major drawbacks in terms of reliability and experimental effort. Design/methodology/approach: The study is based on the combination of real experimental activities and simulated ones. Findings: The main findings of this work consist into validation of the proposed process chain, which proves to be effective in terms of process flexibility (additive manufacturing, burnishing and process simulation acting synergistically), cost and time reduction and final output quality, encouraging customer involvement towards customization. Originality/value: This paper contributes to current research on the application of burnishing process, an easy to implement and environmentally friendly post-processing method to improve the performance of AM products, by providing a unique perspective integrating a reliable simulation model. Other researchers can employ these outcomes towards manufacturing of the future. A reduced version of this work has been previously published in Procedia Computer Science (Sanguedolce, Rotella, Saffioti & Filice, 2021)Peer Reviewe

physics based modeling of machining inconel 718 to predict surface integrity modification

Abstract Inconel 718 nickel-based super alloy is widely used in aerospace, nuclear and marine industries due to its important thermo-mechanical properties and excellent corrosion resistance. However, the possibility to produce parts with a superior surface quality (e.g. enhanced surface integrity) still represents a challenge for manufacturing industry since the standard processing parameters are not suitable when difficult-to-cut materials are involved. Thus, predictive models represent a useful tool to simulate the material behavior during machining. Physics based computational analysis is an excellent technique to analyze the micro-scale phenomena (e.g. dynamic recrystallization, density of dislocation changes) taking place during the plastic deformation processes. Thus, it represents an important tool to optimize the cutting process achieving the desired characteristics of the machined surface. This work presents a physics based model developed to assess the micro-mechanical behavior of Inconel 718 super alloy subject to severe machining operations. Results show the good capability of the model to properly deal with the main physical phenomena taking place during the process and to correctly predict the main surface modifications which affect the final product performance