On high speed wire mills with low rolling speeds, the heating temperature of the billet of the wire mill is similar to that of the bar mill. The heating temperature of steel billets is mainly determined by the structural transformation temperature in the iron carbon phase diagram. At the same time, the requirements of the steel rolling process must be met. Generally, the heating temperature of steel billets is between 1050 and 1250 degrees Celsius. To determine the specific heating temperature, it also depends on the steel type, billet section specification, controlled cooling start temperature, and rolling process and equipment conditions.

Heating speed and time

The heating speed of steel billets usually refers to the rising speed of the surface temperature of steel billets per unit time, expressed in “Celsius degrees per hour”. In actual production, the heating speed is expressed in terms of the time (min/cm) required to heat a steel billet per unit thickness to a specified temperature, or in terms of the thickness of the steel billet heated per unit time (cm/min). The heating time of steel billets usually refers to the total time required for steel billets to reach the discharge temperature from normal temperature.

The heating speed and time are influenced by the thermal load and heat transfer conditions of the furnace, the billet specification, and the thermal conductivity coefficient of the steel grade. When the heating speed is high, the heating capacity of the furnace can be fully utilized, with short furnace time, low burning loss rate, and low fuel consumption.