after rolling and controlled cooling process the heat transfer process generally includes the following two stages: the first stage quench segment, steel leaving the finishing mill finish rolling temperature, the rapid cooling device, as soon as possible by rapid cooling. This stage of the heat transfer by forced convection boiling fish turbulent forced convection heat transfer in two ways. Steel into the cooler, due to the steel surface temperature is much higher than the saturation temperature of the water, the water temperature rising to boiling point and gasification, and dynamic vapor film formed in the steel wall. The jets ≥ 1.0 MPa pressure impact the steel surface, full break the vapor film, steel outer wall of the mobile and the promotion of the boiling process, this heat transfer process with high heat flow, so that the surge of heat transfer coefficient. The second phase of the slow cooling stage, the steel by rapid cooling device, the natural convection cooling in air, at this stage of steel section of the heat redistribution. These two processes belong to the heat exchange between the rolling and the external environment (phase change heat excluded). Rolling internal rolling at what stage they are heat conduction process. In other words, the internal heat of the metal reached the metal surface by heat conduction to the surrounding medium by the metal surface by radiation and convection pass, causing the temperature changes throughout the rolling.

According to the thermal conductivity of the cooling process, rapid cooling after rolling, mainly in the following two ways:

(1) water-cooled: strong convective heat transfer;

(2) air-cooled: the equivalent of the thermal radiation and contact heat transfer.

after rolling control simulation of the cooling

Using ANSYS finite tool software, the use of finite element for solving rolling and controlled cooling temperature field simulation calculation of thermal conductivity, specific heat capacity, ambient temperature of the cooling water temperature, material density, etc., at different temperatures, the thermal conductivity coefficient, specific heat capacity is not constant, with the material organization of state and temperature changes, therefore, also change over time. In accordance with the relevant literature and field parameters to control the cooling simulation selection of GCr15 bearing steel, the material density of 7 810 kg/m3,; air temperature of 25 ° C; cooling water temperature is 20 ℃.

Rolling the continuous cooling process, the transient analysis to simulate the temperature changes of the different cooling methods, taking into account the steel wear the water, the lowest temperature of the surface can not be less than 350 ° C, so as not to produce marten site, so the water flow should be controlled good water and secondary wear different water simulation analysis of time to wear.