Three ways of heating seamless tube billet

In the production process of SMLS, the heating process of the billet is actually the heat transfer process of the heat source. The temperature difference is the basic condition for heat transfer. Only when there is a temperature difference can heat spread. According to whether the temperature of the object changes during the heat transfer process , Heat transfer can be divided into two states: stable heat transfer and unstable heat transfer. Steady-state heat transfer refers to the heat transfer phenomenon in which the temperature of the object does not change with time during the heat transfer process. Unstable heat transfer refers to the heat transfer phenomenon in which the temperature of the object is constantly rising during the heating process, and the heat is continuously transferred from the surface of the object to the interior, that is, the heat transfer phenomenon in which the temperature changes with time.

When the seamless tube billet is heated, the heat source can be transmitted in three ways: radiation, conduction, and convection:

1. Radiation

Convection and conduction are two heat transfer methods that must be in contact with objects to transfer heat, while radiation is a heat transfer method in which objects can conduct heat from one object to another without contact;

2. Conduction

Conductive heat transfer is generally transferred from the high-temperature part to the low-temperature part of the same object, and can also be transferred from the high-temperature object to the low-temperature object in close contact with it. Conductive heat transfer of special-shaped tube billet has the following characteristics:

One is that conduction and heat transfer only have microscopic thermal motion of particles, not macroscopic motion or displacement. Therefore, conduction heat transfer mainly occurs in solids such as metals and refractory materials;

Second, the particles must collide and contact in order to conduct conduction and heat transfer. Therefore, when there are a large number of pores in the solid, the conduction heat transfer is greatly weakened. The heat insulation materials commonly used in heating furnaces are made according to this principle;

3. Convection

Convective heat exchange is due to the transfer of heat energy from high temperature to low temperature during the contact process when the fluid moves in a macroscopic manner. Therefore, the medium of this heat transfer method can only be liquid (including flowing metal melt of special-shaped tube billet) and gas. Convective heat exchange can occur between the fluid and the solid surface, or inside the fluid.