What exactly is the difference between normalizing, annealing, and quenching?

The steel is heated to a certain temperature and kept warm at this temperature, and then slowly cooled to room temperature There are several types of annealing, such as complete annealing, spheroidization annealing, and stress relief annealing. Heating the steel to a predetermined temperature, holding it warm for a period of time, and then slowly cooling it with the furnace is called complete annealing. The purpose is to reduce the hardness of the steel and eliminate the uneven structure and internal stress in the steel.

The steel is heated to 750 degrees, kept warm for a period of time, slowly cooled to 500 degrees, and finally cooled in air called spheroidization annealing. The aim is to reduce the hardness of the steel and improve the cutting performance, mainly for high-carbon steels. Stress relief annealing, also known as low-temperature annealing, heats the steel to 500 600 degrees, keeps it warm for a period of time, cools slowly with the furnace to below 300 degrees, and then cools it at room temperature.

During the annealing process, the microstructure does not change, and the internal stress of the metal is mainly eliminated. Normalizing heats the steel to 30-50 above the critical temperature, and after holding it for an appropriate time, the heat treatment process of cooling in still air is called normalizing. The main purpose of normalizing is to refine the structure, improve the properties of the steel, and obtain a structure close to equilibrium.

Compared with the annealing process, the main difference between normalizing is that the cooling rate of normalizing is slightly faster, so the production cycle of normalizing heat treatment is shorter. Therefore, when annealing and normalizing can also meet the performance requirements of parts, normalizing should be selected as much as possible. Quenching heats the steel to a certain temperature above the critical point (the quenching temperature of No. 45 steel is 840-860, and the quenching temperature of carbon tool steel is 760 780), holds it for a certain time, and then cools it in water (oil) at an appropriate rate to obtain a martensitic or bainite structure.

The main difference between quenching and annealing and normalizing treatment in the process is the fast cooling rate.

Quenching, normalizing, annealing, and tempering are all heat treatment processes of steel, and in order to achieve different properties of the workpiece, the heat treatment process adopted to improve the internal structure of the workpiece. The difference between them is that the workpiece is heated to different temperatures first, and the workpiece is cooled in different cooling methods and cooling speeds to achieve the purpose of changing the metal structure. Normalizing heats steel or steel parts to an appropriate temperature above the critical point AC3 or ACM for a certain period of time and then cools it in the air to obtain a heat treatment process of pearlitic structure.

Annealing is a heat treatment process in which the sub-eutectic steel workpiece is heated to 20-40 degrees above AC3, and after holding for a period of time, it is slowly cooled (or buried in sand or lime cooled) with the furnace to below 500 degrees and cooled in air. Quenching is a heat treatment process in which the austenitization of steel is cooled at an appropriate cooling rate, so that the workpiece undergoes unstable microstructure transformation such as martensite in all or a certain range within the cross-section. The quenched workpiece is heated to an appropriate temperature below the critical point AC1 for a certain period of time.

Martensite structure is an unbalanced structure obtained after quenching of steel, which has high hardness but poor plasticity and toughness. The hardness of martensitic increases as the carbon content of the steel increases. After tempered steel, it is reheated to a certain temperature below the critical temperature, kept warm for a certain time, and then cooled to room temperature.

Quenched steel parts generally cannot be used directly, and must be tempered before they can be used. Because of the high hardness and brittleness of quenched steel, brittleness often occurs when used directly. Through tempering, internal stress, brittleness can be reduced, and toughness can be improved. On the other hand, the mechanical properties of the quenched steel can be adjusted to achieve the use performance of the steel.

What does normalizing, annealing, quenching, and tempering mean? Have you figured it all out?

1. Different meanings: quenching and tempering are both part of the heat treatment process, and the two are just different in the processing time order to achieve different process purposes. To put it simply, the steel is heated above the critical temperature, and then cooled sharply to increase the hardness of the steel, this process is called quenching.

After quenching, the cooling stress is too great, which makes the steel brittle and affects the use. Therefore, the quenched steel is heated to about 200 degrees, so that the cooling stress can be relieved, and the effect of rigidity and softness is obtained, which is called tempering.

2. Quenching: The heat treatment process of heating the steel to a certain temperature above the critical point, maintaining it for a certain time, and then cooling it in water (oil) at an appropriate speed to obtain a martensitic or bainite structure is called quenching.

3. Tempering: After the steel parts are hardened, they are heated to a certain temperature below the critical temperature, kept warm for a certain time, and then cooled to room temperature.

Steel annealing, normalizing, and quenching are all different ways of heat treatment of steel materials.

1.The annealing of steel is to overheat the steel to a stable temperature through trembling, and then control the temperature to decrease slowly, eliminating the internal stress in the steel in a slow cooling way, and improving the plasticity and toughness. This type of heat treatment is suitable for steel processing and manufacturing processes that require increased toughness and machinability of the material.

Specifically, annealing causes the grain growth of the steel and improves the shape, while reducing its hardness and improving plasticity and toughness.

2.Normalizing of steel is to first heat the steel to its highest point and hold it for a period of time, and then quickly quench and solidify it in water or oil. This method can increase the density and hardness of the steel and enhance the strength of the material, but relatively reduce the toughness.

Normalizing is suitable for field fittings that require increased strength and hardness of steel, such as making high-strength structural parts.

3.The quenching of steel is the heating of steel to its highest point and then rapid cooling to increase the hardness, strength, and wear resistance of the steel. However, the quenching process can lead to defects such as cracks or deformation inside the steel, which can also reduce the toughness and corrosion resistance of the material.

Quenching is suitable for tools and mechanical parts that require high hardness, high strength, and wear resistance.

In general, the annealing, normalizing and quenching of steel requires different heat treatment methods for different workpieces to improve the properties of the steel and adapt to different applications.