PROCESS OF DIRECT LASER GROWTH OF HEAT-RESISTANT ALLOY: INFLUENCE OF POWER AND HEAT TREATMENT ON MICROSTRUCTURE AND MECHANICAL CHARACTERISTICS

The microstructure and tensile mechanical properties of samples made of a heat-resistant nickel-based alloy obtained using the direct energy and material supply (LP-DED) process have been studied. The power of the laser radiation varied from 1200 to 2000 watts. It was noted that low laser power can lead to higher cooling rates and defects in the microstructure of the samples. The radiation power of 2000 W resulted in the highest mechanical properties under tension. The effect of heat treatment on microstructure, hardness and tensile properties was investigated. When examining the samples after destruction, it was found that defects in the form of non‒melts and cracks are present in the fractures of the samples obtained at a power of 1400 - 1800 watts. In the fractures of the samples made at a laser power of 1200 and 1600 W, there are non-molten powder particles. On the fracture surfaces of all samples, pits and the classic shape of a cup and cone were present, indicating a viscous fracture mechanism. It was found that heat treatment can completely homogenize the microstructure, lead to relatively homogeneous, equiaxed grains and increase the hardness of the material. Heat treatment reduces the anisotropy of properties, leads to an increase in the level of tensile properties at different laser power. The study provides an initial basis to help designers and specialists with the choice of laser power, as well as to understand its effect on a heat-resistant alloy, its effect on microstructure and mechanical properties at room temperature.

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