Introduction
Quenching and tempering bed is one of the most widely used technologies in heat treatment. It is a process of heat treatment by heating materials at specified temperature and placing them in an appropriate quench medium (gas, water, oil, etc.) to obtain certain structure, mechanical properties and electrical properties. The temperature and quenching medium of the quenching and tempering bed are determined based on its application.
Basic parameters of quenching and tempering bed
1. The temperature of quenching and tempering bed: the temperature of quenching and tempering bed is same with that of annealing, tempering, normalizing and tempering or hardened steel. Depending on the purpose, different temperatures can be adopted. For example, quenching and tempering of steel at a temperature of 750°C (1400°F) or below will generally result in a surface hardness of at least 800HB, while a steel quenched at 1000°C (1800°F) will result in a surface hardness of 1000–1200HB.
2. Quenching medium: the quenching medium is usually oil, water or air. Oil is used most commonly, because it cools slowly, enabling the material to be fully transformed into austenite during the heat treatment process.
3. Heat treatment time: this is also an important technical parameter of the quenching and tempering bed. Generally, it depends on the quenching time(in hours) and the tempering time(hours). Longer heat treatment time will lead to a better comprehensive performance and microstructure.
4. Cooling rate: this is determined by the quenching medium. The cooling rate of oil is much slower than that of water, so it can be used to obtain finer grains.
5. Quenching temperature: the quenching temperature determines the quenching hardness and microstructure. Generally, the quenching hardness increases with the quenching temperature, and the quenching microstructure is also affected. A higher quenching temperature will lead to a coarse grain structure and a lower quenching temperature will lead to a finer grain structure.
6. Temper tempering temperature: the temper tempering temperature is usually lower than the quenching temperature, usually around 500℃. This temperature is determined by the strength and toughness of the material.
Conclusion
Quenching and tempering bed is a widely used technology in heat treatment. Its parameters need to be considered carefully according to the purpose of application. The parameters mentioned in this article are some of the most basic parameters, which will have a great influence on the heat treatment results. Therefore, attention should be paid to them.
