Experimental electric furnace
Annealing is to heat the workpiece to the appropriate temperature, using different holding time according to the material and the workpiece size, and then slowly cooling, in order to make the internal structure of the metal reach or close to equilibrium, obtain good process performance and performance, or further quench Prepare for organization.
Normalizing is to cool the workpiece to a suitable temperature and then cool it in the air. The effect of normalizing is similar to annealing, but the resulting structure is finer, which is often used to improve the cutting performance of materials, and sometimes used for some less demanding parts. As the final heat treatment.
Quenching is the rapid cooling of the workpiece after heating and holding it in a quenching medium such as water, oil or other inorganic salts or organic aqueous solutions. After quenching, the steel becomes hard, but at the same time becomes brittle. In order to eliminate brittleness in time, it is generally necessary to temper in time.
In order to reduce the brittleness of the steel, the quenched steel is subjected to long-term heat preservation at a suitable temperature higher than room temperature and lower than 650 ° C, and then cooled. This process is called tempering.
Annealing, normalizing, quenching and tempering are the "four fires" in the overall heat treatment. Among them, the quenching and tempering are closely related, and often used together, they are indispensable.
The "four fires" evolved different heat treatment processes with different heating temperatures and cooling methods. In order to obtain a certain strength and toughness, the process of combining quenching and high-temperature tempering is called quenching and tempering. After quenching some alloys to form a supersaturated solid solution, it is kept at room temperature or a slightly higher temperature for a longer period of time to increase the hardness, strength or electrical magnetic properties of the alloy. Such a heat treatment process is called aging treatment.