Examinando por Autor "Celentano, D.J."

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A thermo-metallurgical model for laser surface engineering treatment of nodular cast iron
(Springer Nature, 2021-02-08) Boccardo, A.D.; Catalán, N.; Celentano, D.J.; Ramos-Moore, E.
Heat treatments are frequently used to modify the microstructure of cast irons according to experimental parameters. Among these, laser surface engineering (LSE) has become relevant for being a highly localized treatment with rapid heating and cooling of the irradiated area resulting in minimal distortion of the workpiece. This work presents and experimentally validates a thermo-metallurgical model able to predict the phase transformations occurring during the LSE treatment of nodular cast iron when it is subjected to different laser beam powers and scanning velocities. For this purpose, an experimental characterization of the thermal history and final microstructure is performed for several operating scenarios. In particular, significant changes in the microstructure can be seen at high powers and low scanning velocity where the matrix is transformed into ledeburite and martensite. The final phase volume fractions predicted by the proposed model along the depth of the sample are compared with the corresponding experimental measurements. The results obtained in the simulation are in good agreement with the experimental measurements. This work highlights the use of our model to be systematically applied for the design and optimization of LSE treatments on cast irons.
Numerical simulation of austempering heat treatment of a ductile cast iron
(Springer Nature, 2015-11-19) Boccardo, A.D.; Dardati, P.M.; Celentano, D.J.; Godoy, L.A.; Górny, M.; Tyrała, E.
This paper presents a coupled thermo-mechanical-metallurgical formulation to predict the dimensional changes and microstructure of a ductile cast iron part as a consequence of an austempering heat process. To take into account the different complex phenomena which are present in the process, the stress-strain law and plastic evolution equations are defined within the context of the associate rate independent thermo-plasticity theory. The metallurgical model considers the reverse eutectoid, ausferritic, and martensitic transformations using macro and micro models. The resulting model is solved using the finite element method. The performance of this model is evaluated by comparison with experimental results of a dilatometric test. The results indicate that the experimental evolution of deformation and temperature are well represented by the numerical model.