International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The effect of different heat treatments on the microstructure and mechanical properties of the C45 and S355J2 steel forgings has been presented. Samples of the same forgings, but subjected to the different heating treatments, were prepared and tested by using opticalmicroscopy, tensile machine, and hardness tester. It was observed that the requested mechanical properties of the forgings and uniform structure can be achieved by determining the appropriate heating treatment parameters.

Nickel aluminum bronze with the composition CuAl9Ni3Fe3 was investigated in this paper. After casting, the alloy was annealed at 900 °C followed by quenching. Thermodynamic calculation of the existing phases was performed using the ThermoCalc software. Quenched NAB samples were further aged for 1 h at 300 °C, 350 °C, and 400 °C. During the experiment, the values of hardness and microhardness were examined using standardized Vickers measurement methods. Microstructural analysis was performed using scanning electron microscopy equipped with an energy-dispersive spectrometer. During the precipitation hardening, β’ martensite eutectoidly decomposed into α and κ phases causing an increase in mechanical properties.