Theory and Technology of Direct Laser Deposition

Presently the additive technologies in manufacturing are widely developed in all industrialized countries. Replacing the traditional technology of casting and machining with additive technologies, one can significantly reduce material consumption and labor costs. They also allow obtaining products with desired properties. The most promising for manufacturing large-sized products is the additive technology of high-speed direct laser deposition. Using this technology allows to create complex parts and construction to one technological operation without using addition equipment and tools. This technology allows decreasing of consumption of raw materials and decrease amount of waste. Equipment for realization of DLD technology is universal and based on module design principle. DLD is based on layer-by-layer deposition and melting of powder by laser beam from using a sliced 3D computer-aided design (CAD) file. The materials used are powders based on Fe, Ni, and Ti. This chapter presents the results of machine design and research HS DLD technology from various materials

Features of the Powder Application in Direct Laser Deposition Technology

The chapter presents the basic aspects of the use of metal powders in one of the main additive technologies—direct laser deposition (DLD). Direct laser deposition refers to a group of direct energy deposition (DED) methods and is analogous to Laser Metal Deposition (LMD) technology. The main requirements applied to DLD used metal powders are analyzed and substantiated. The influence of the basic properties of the powders on the quality of the deposited samples is demonstrated. An example of incoming quality control of powders, allowing its application in DLD technology, is presented. The results of experimental research on obtaining quality control samples for the most used metallic materials are presented. The results of structure and properties studies for the main groups of alloys based on iron, nickel, and titanium are shown. The potential for manufacturing products for various areas of industry using DLD has been demonstrated

Investigation of the mechanical properties and corrosion behaviour of hybrid L 80 Type 1 and duplex steel joints produced by magnetically impelled arc butt welding

In the field of deep geothermal energy, the mono-tube design will be increasingly used in the future, as significant cost savings can be expected in the production of boreholes up to depths of 6000 m. The previously used bolting of the pipe lengths by means of sleeves contributes significantly to the construction costs. In addition, there is an increased risk of failure for the sleeve bolting, especially if different materials have to be used in different layers for the purpose of increasing the corrosion resistance. Magnetically Impelled Arc Butt Welding (MIAB) was used for direct welding of pipe segments with complete elimination of socket bolting. In the process, the casing material (L80 Type 1), which is a cost-effective standard material, and a corrosion-resistant duplex steel (1.4462) were hybrid welded. The results show excellent properties both in terms of mechanical properties and corrosion resistance. It is shown that the advantages of the MIAB process in joining these different materials can successfully overcome the metallurgical challenges. This new approach for the production of borehole liners can contribute significantly to cost reduction in the construction of geothermal boreholes

Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process

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