Simulation and experimental study of induction heat treatment of titanium disks

• The influence of the inductor current in the range 2.7–4.5 kA on the exposure temperature from 800°C to the melting temperature (about 1670°C) of the titanium was determined. • Changes in the surface morphology of the titanium disks were studied over a wide temperature range. • At the induction heat treatment (1000–1500°C) the scale was spontaneously separated from the surfaces of titanium. • A high-strength oxide sublayer was formed under the thick titanium dioxide scale. • The thick scale was preserved on the surfaces of semi-molten titanium disks. During induction heat treatment (IHT) of titanium disks, the influence of the main electrotechnological parameters, in particular the inductor current, on the temperature of their surfaces was established at an exposure within t = 5 min. In the course of numerical simulation, i.e. when solving the self-consistent boundary value problem of electrodynamics and thermal conductivity for the "inductor – titanium disk" system, the influence of the inductor current in the range 2.7–4.5 kA on the average exposure temperature of the titanium disk was determined, which varied from 800–850°C to the melting temperature (about 1670°C) and above. In order to confirm numerical calculations, experimental studies on IHT in the same temperature range were performed. In addition to the inductor current I IND varying in the range from 2.7 to 4.5 kA, the influence of the corresponding value of the electric power P E in the range from 0.21 to 0.95 kW on the exposure temperature during IHT was considered. Changes in the surface morphology of the titanium disks were studied over a wide temperature range. The initial oxide coating was retained on the surfaces of the samples processed at a minimum exposure temperature of T = 800–850°C. A thick scale of titanium dioxide was also preserved on the surfaces of semi-molten titanium disks. In the IHT exposure range at temperatures from 1000–1050°C to 1500–1550°C, the scale was spontaneously separated from the surfaces of titanium disks; however, a high-strength oxide sublayer was formed under it.