Abstract
The work is devoted to the development of a model for calculating transient quasiperiodic temperature fields arising in the direct deposition process of thin walls with various configurations. The model allows calculating the temperature field, thermal cycles, temperature gradients, and the cooling rate in the wall during the direct deposition process at any time. The temperature field in the deposited wall is determined based on the analytical solution of the non-stationary heat conduction equation for a moving heat source, taking into account heat transfer to the environment. Heat accumulation and temperature change are calculated based on the superposition principle of transient temperature fields resulting from the heat source action at each pass. The proposed method for calculating temperature fields describes the heat-transfer process and heat accumulation in the wall with satisfactory accuracy. This was confirmed by comparisons with experimental thermocouple data. It takes into account the size of the wall and the substrate, the change in power from layer to layer, the pause time between passes, and the heat-source trajectory. In addition, this calculation method is easy to adapt to various additive manufacturing processes that use both laser and arc heat sources.
Highlights
Additive technologies, in particular direct energy deposition (DED) technologies, are actively developing and are already used in modern production in the manufacture of metal parts and repair and restoration work [1,2,3,4,5]
Electron beam, plasma, and arc are used as the main heat source, and the filler material can be used both in the form of powder and in the form of wire
In the case of WAAM, the thermocouple was located on the substrate surface at a distance of 3 mm from the cylindrical wall
Summary
In particular direct energy deposition (DED) technologies, are actively developing and are already used in modern production in the manufacture of metal parts and repair and restoration work [1,2,3,4,5]. A characteristic feature of the direct deposition process is that the material undergoes multiple heating and cooling processes, including partial remelting of already-formed layers Such a complex temperature field, which changes both in space and in time, significantly affects the local microstructure and its evolution, residual stresses, and deformations, as well as the distribution of defects, which can significantly affect the mechanical properties, and the entire product’s reliability. The melt pool has a characteristic size of the order of a few millimeters, while the model of the entire product is usually on a meter or sub-meter scale As a consequence, such calculations require enormous computing power and time. In comparison with the above models, the peculiarity of this work is to provide a fast, simple, and universal, but at the same time reliable, analytical method for calculating transient temperature fields in the AM process. The application of this method will make it possible to study the degree of influence of local quasiperiodic temperature fields, which always accompany direct deposition processes, on structural phase transformations
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