RETRACTED ARTICLE: Modeling the correlation between Charpy impact energy and chemical composition of functionally graded
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ORIGINAL ARTICLE
Modeling the correlation between Charpy impact energy and chemical composition of functionally graded steels by artificial neural networks Ali Nazari
Received: 12 April 2012 / Accepted: 21 June 2012 Ó Springer-Verlag London Limited 2012
Abstract In the present study, the Charpy impact energy of ferritic and austenitic functionally graded steel produced by electroslag remelting has been modeled in crack divider configuration. To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrode. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. Vickers microhardness profile of the specimen has been obtained experimentally and modeled with artificial neural networks. To build the model for graded ferritic and austenitic steels, training, testing and validation using respectively 174 and 120 experimental data were conducted. A good fit equation that correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterward, the Vickers microhardness of each layer in functionally graded steels was related to the Charpy impact energy of the corresponding layer. Finally, by applying the rule of mixtures, Charpy impact energy of functionally graded steels in crack divider configuration was found through numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments. Keywords Chemical composition Microhardness Charpy impact energy Crack divider Artificial neural networks ESR Ferritic FGS Austenitic FGS
A. Nazari (&) Department of Materials Engineering, Saveh Branch, Islamic Azad University, Saveh, Iran e-mail: [email protected]
1 Introduction FGMs are multiphase systems in which their composition varies gradually in some direction to obtain a unique mechanical, thermal and electrical property that distinguishes them from the conventional composites which in general are of discrete, piecewise nature with sharp interfaces [1–4]. There is not enough study on the plastic behavior of FGMs. Among these few works, most of the researchers have been modeled their work with the aid of conventional flow theories, which are the one of the best tools that has ever proposed. For example, some of them have tried to use J2 flow theory [5–7] but the empirical investigations have not been linked to the obtained results because of the difficulty of FGMs fabrication. Okolednik [8] although has used J integral concept to model several materials with yield stress gradient, but his studies were not confirmed by the experimental results. One of the FGMs with elastic–plastic behavior is functionally graded steel (FGS) that have been produced from austenitic stainless steel and carbon steel using electro slag refining (ESR) method [9, 10]. I
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