Annealing: It is to heat the workpiece to an appropriate temperature, use different holding times according to the material and workpiece size, and then slowly cool it. The purpose is to make the internal structure of the metal reach or approach a state of equilibrium, obtain good process performance and use performance, or prepare the organization for further quenching.
Quenching; It is to heat and keep the workpiece, and then quickly cool it in a quenching medium such as water, oil or other inorganic salts, organic aqueous solutions. After quenching, the steel becomes hard, but also brittle. In order to reduce the brittleness of steel parts, the quenched steel parts are kept warm for a long time at an appropriate temperature above room temperature and below 710℃, and then cooled. This process is called tempering.
The difference between annealing and tempering is: (Simply put, annealing means no hardness, while tempering still retains a certain hardness.) Tempering: The structure obtained by high temperature tempering is tempered martensite. Heat treatment is a metal heat processing process that heats, keeps warm, and cools metal materials in a certain medium to control their properties by changing the metallographic structure on the surface or inside of the material. Sometimes there are only two processes, heating and cooling. These processes are connected to each other and cannot be interrupted.
API 5L BN Line Pipe
