![]() ![]() Therefore, understanding the growth of dendrites is considered important for the management of the basic processes of crystal formation and growth. All these interactions take place at the interface between dendrites and melt. The formation of morphological forms of dendrites is associated with the development of such chemical processes as microsegregation, thermal (release of latent heat), and mechanical processes (changes in volume during phase transformation). Dendrites are a ubiquitous crystalline form in solidifying alloys and supercooled melts, as their shape is most suitable for efficient heat and mass transfer on a small scale. The microstructure of the solidification of the weld pool begins with the formation of equiaxed or columnar dendrites, regardless of the welding conditions and deoxidation process.ĭendritic growth is a fundamental crystal growth phenomenon that accompanies most casting and solidification processes. The weld metal in arc welding of carbon and low-alloy steels in accordance with the equilibrium phase diagram (Fe-C diagram) demonstrates the partial solubility of alloying and impurity elements in solids with a peritectic reaction. Unfortunately, there are not many investigations of the initial part of this process. Based on this approach, the modelling of the structure should begin with consideration of the conditions for the nucleation and growth of dendrites in the weld pool, the formation of grains of the primary structure, and end with the formation of the secondary structure. The formation of the structure of the weld is a continuous fast-flowing process that begins with the melting of the base and filler materials and ends with the cooling of the metal to ambient temperature. This approach does not allow to take into account the influence of the initial process parameters on the nucleation and growth of primary grains, which leads to some uncertainty in modelling the final results. In this case, the conditions for the formation of the structure as a result of recrystallization are considered, while the parameters of the primary structure are determined by an experimental or computational-experimental methods. At present, programs have become widespread, which are based on modelling the composition of the secondary structure of the weld metal. This approach makes it possible to effectively and reliably select such a combination of technological parameters of the welding process, which will provide the required level of mechanical properties of the welded joint. A wide variety of metals, types of welded joints and technologies used for these purposes led to the development of computer modelling with the “composition-structure-properties” system. Currently, welding remains one of the most widespread technologies in the manufacture of metal structures. ![]()
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