In the application of surface modification technology, nitrogen and oxygen are sealed in a vacuum furnace, while titanium casting specimens were heat-treated at reduced atmospheric pressure and at a temperature lower than titanium's transformation point. The samples formed solid-solution layers of functionally graded structures on the surfaces. cast specimens of titanium materials were made with commercial Pure titanium (CP titanium) and titanium alloy (Ti-6 Al-7 Nb). Experiments performed on processed specimens included tensile strength, elongation, Vickers hardness, deformation of the heat treatment test and SEM image observation. Surface hardening of titanium increased, but surface hardening did not influence tensile strength. Specimens did not deform due to the influence of the heat treatment. Elongation increased slightly, but the gap size could not be confirmed before or after the treatment. Reforming could be observed only in the limited surface of the specimens on SEM images of the metal surface.