Heat Transfer Mechanics of Controlled Cooling after Rolling reinforcing steel bar
Reinforcing steel bar, commonly also known as rebar, is a kind of steel used in construction works in order to provide hold and strength where needed. After rolling process, a controlled cooling is applied in order to achieve the desired properties for the rebar. This paper aims to discuss the heat transfer mechanics behind the controlled cooling of the rebar after the rolling process.
When steel is heated and then cooled, a series of events takes place, which are referred to as thermomechanical processing. The heat transfer mechanics of the controlled cooling after rolling rebar involves both convection and conduction methods. The convection method is where heat is transferred between the surface of the steel and the air via air movement, and conduction is where heat is passed through the steel from one point to another.
The first mechanism of transfer of heat is through conduction. This means that heat is conducted through the rebar from the location where it is rolled and the area where the temperature needs to be lowered. This is done via heat transfer from the hotter area to the colder area. The use of conveyor belts in rolling processes allows for better conduction of heat, as the metal slides along its surface. The friction caused by the movement of the metal on the belt helps to transfer heat faster and ultimately enables the desired temperature decrease.
The second mechanism of transfer of heat is through convective heat transfer. This is when heat is transferred through the air that is in contact with the rebar. The hotter parts of the rebar emit heat in the form of radiation, and the cooler parts absorb it. The radiation heats up the air in which the rebar is located, and overtime by means of the air currents, the heat is moved around different parts of the rebar so that the desired temperature decrease can be achieved.
Both mechanisms of heat transfer are used for cooling the rebar after it has been rolled. As mentiosioned before, the conduction is done to transfer the heat from the hotter areas to the colder parts of the steel and the convection is used to further cool the rebar. This swapping of heat between the cooler and hotter areas helps to make the temperature gradient across the rebar uniform, while also allowing a certain amount of heat to be radiated away from its surface.
In conclusion, heat transfer mechanics of controlled cooling of the rebar after its rolling process involves two main mechanisms: conduction and convection. The conduction is used to transfer heat from the hot region to the cold region along the length of the steel, while the convection helps to further cool the rebar by transferring heat through the air around it. The conducting and convection play important roles in achieving the desired temperature reduction across the rebar, ultimately enabling it to retain its desired mechanical properties.
