2_1-11.doc - NEW APPROACH TO THE DESIGN OF ADVANCED WELDING MATERIALS V Mazurovsky1 M Zinigrad1 L Leontev2 and V Lisin2 1 Materials Research Center

2_1-11.doc - NEW APPROACH TO THE DESIGN OF ADVANCED WELDING...

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NEW APPROACH TO THE DESIGN OF ADVANCED WELDING MATERIALS V. Mazurovsky 1 , M. Zinigrad 1 , L. Leontev 2 , and V. Lisin 2 1 Materials Research Center, College of Judea and Samaria, Ariel, Israel 2 Institute of Metallurgy, Ural Division of the Russian Academy of Sciences, Ekaterinburg, Russia ABSTRACT. A new approach to the design of welding and hardfacing materials is developed. The new approach is shown to be based on modeling of the physicochemical processes that occur in all stages of the formation of a welded joint and its interaction with the environment. A concise description of the development of a computer-aided design system for welding materials is given. An example of the practical implementation of the new method for designing hardfacing flux-cored wires is presented. Introduction Researchers have been engaged in the development of welding materials for more than 100 years, and during this entire period, questions concerning the fusion of welding materials and the formation of the weld metal have been subjected to thorough study. It was found that the physicochemical processes taking place during fusion welding determine the course of an industrial welding process and thus its result, i.e., the composition, structure, and properties of the weld deposit. Fusion welding is a complex process primarily because of the complexity of the formation of the weld pool, which is a multicomponent, multiphase system with a nonuniform temperature field and complex mass- and heat-transfer processes. The mass-transfer processes that occur on the metal–slag and metal–gas boundaries determine the chemical composition of the weld metal, and, consequently, they largely determine its mechanical properties. However, the properties of a weld, especially of a welded joint, are shaped not only by the chemical composition of the metal, but also by the crystallization processes that occur in it. The thermodynamic and kinetic characteristics of the most important chemical reactions in the liquid melt have been thoroughly investigated in numerous studies [1-5], and kinetic analysis [5, 6] has been used successfully to predict the chemical composition of the weld deposit. However, the processes that occur during the subsequent cooling and crystallization have been studied to a far smaller extent due to the complexity of their course. The needs of practical metallurgy were satisfied by the black-box approach, i.e., determination of the known state at the entrance (in the molten metal) and the result at the exit (in the solid alloy), which was attained by the tedious and costly trial-and-error method. However, as production was intensified and automated, it became necessary to develop and employ predictive methods for evaluating the physicochemical processes in the final stage of the formation of the cast metal. This was promoted to a significant degree by the use of modern computer technology. Modeling of the solid-phase transformations in a weld deposit as it crystallizes and employment of the results for
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