Abstract
Nickel-based superalloys have several applications for components exposed to high temperatures and high strain rate loading conditions during services. The objective of this study was to investigate the tensile properties of Inconel 718 produced using the laser metal deposition technique. Specimens with different heat treatments were investigated. Experimental tests were performed at the DYNLab at Politecnico di Torino (Italy). The temperature sensitivity was investigated between 20 °C and 1000 °C on a Hopkinson bar setup at a nominal strain rate of 1500 s−1. The specimens heating was obtained by means of an induction heating system, and the temperature control was performed by thermocouples, an infrared pyrometer, and a high-speed infrared camera. The thermal images were analyzed to check the uniformity of the heating and to investigate the presence of adiabatic self-heating. The results showed that the materials strength exhibited a significant drop starting from 800 °C. The strain rate influence was investigated at room temperature, and limited sensitivity was found covering six orders of magnitude in the strain rate. A preliminary analysis of the fracture mode was performed. Finally, different solutions for the strength material modeling were proposed and discussed with the aim of identifying models to be used in finite element simulations.
Highlights
Nickel-based superalloys show an excellent combination of properties
In the case of impact, high deformation of components, or even their failure, occurs in a short time. This loading condition underlines that for the safe design and realization of high-performance engine parts, it is mandatory to understand the plastic behavior in case of combined high temperature and high strain rate conditions
The plastic flow behavior of Inconel 718 was investigated by performing tensile tests on cylindrical dog-bone specimens with a gauge diameter of 3 mm and a gauge length of on cylindrical dog-bone specimens with a gauge diameter of 3 mm and a gauge length of 5 mm with threaded ends
Summary
The most important property is to retain high strength at high temperatures. This characteristic makes this class of material suitable for applications in which the components could be exposed to temperatures even higher than 800 ◦ C [1] during services. In the case of impact, high deformation of components, or even their failure, occurs in a short time. This loading condition underlines that for the safe design and realization of high-performance engine parts, it is mandatory to understand the plastic behavior in case of combined high temperature and high strain rate conditions
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