What happens to the fire color of steel when it is heated with a high-frequency induction heating machine?

When steel is heated with a high-frequency induction heating machine, the thermal movement of internal atoms intensifies as the heating temperature rises. The increase in atomic kinetic energy will excite electromagnetic waves of a certain wavelength. When the temperature exceeds 530°C, the excited electromagnetic waves enter the range of visible waves and can be felt by people's vision. The higher the temperature, the shorter the wavelength, the lighter the color of the light emitted by the steel, and the stronger the brightness.

The visible waves emitted by steel at high temperatures are colored lights, which are called "fire colors" in forging production. The change of fire color with temperature is shown in the table below. Experienced heating workers and forgers can roughly judge the temperature of the steel surface based on the fire color. The surface temperature of the heated steel can be more accurately measured by observing the fire color with the help of an optical pyrometer.

This article briefly introduces the changes in the fire color of steel when it is heated. I hope it will be helpful to your heat treatment work. If you don’t understand anything, please feel free to leave us a message.