Annealing, normalizing, quenching, tempering definition and classification

a) Types of annealing.

1 Complete annealing and isothermal annealing.

Complete annealing, also known as crystalline annealing, is generally referred to as annealing, which is mainly used for casting, forgings and hot-rolled profiles of various carbon steels and alloy steels with sub-eutectic composition, and sometimes also used for welded structures. It is often used as a final heat treatment for some unimportant workpieces, or as a pre-heat treatment for some workpieces.

2. Spheroidized annealing.

Spheroidized annealing is mainly used for carbon steels and alloy tool steels (such as steel grades used in the manufacture of cutting tools, measuring tools, and molds). The main purpose is to reduce hardness, improve machinability and prepare for later quenching.

3. Stress relief annealing.

Stress relief annealing, also known as low-temperature annealing (or high-temperature tempering), is mainly used to eliminate the residual stress of castings, forgings, welded parts, hot-rolled parts, cold-drawn parts, etc. If these stresses are not relieved, they will cause deformation or cracks in the steel after a certain period of time, or during the subsequent cutting process.

2) Quenching.

In order to improve the hardness, the main forms are through heating, heat preservation, and quick cooling. The most commonly used cooling media are brine, water and oil. The workpiece quenched by salt water is easy to obtain high hardness and smooth surface, and it is not easy to produce soft spots that are not hardened, but it is easy to make the workpiece seriously deformed and even cracked.

The use of oil as quenching medium is only suitable for the quenching of some alloy steels or small-sized carbon steel workpieces with relatively large stability of supercooled austenite.

iii) Tempering.

1. Reduce brittleness, eliminate or reduce internal stress, there is great internal stress and brittleness after quenching of steel, if not tempered in time, the steel will often be deformed or even cracked.

2. Obtain the mechanical properties required by the workpiece, the workpiece has high hardness and high brittleness after quenching, in order to meet the requirements of the different properties of various workpieces, the hardness can be adjusted through the appropriate tempering match, the brittleness can be reduced, and the required toughness and plasticity can be obtained.

3. Stabilize the size of the workpiece.

4. For some alloy steels that are difficult to soften by annealing, high temperature tempering is often used after quenching (or normalizing) to make the carbides in the steel properly aggregate and reduce the hardness to facilitate cutting processing.

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

The meanings of annealing, positive fire socks, quenching, and tempering are:

1. Annealing. The workpiece is heated to the appropriate temperature, different holding times are used according to the material and the size of the workpiece, and then slow cooling (the slowest cooling rate) is carried out in order to make the internal structure of the metal reach or close to equilibrium, and obtain good process performance and service performance.

2. Normalizing. The effect of normalizing is similar to annealing, except that the resulting structure is finer and is often used to improve the clear and closed cutting performance of the material.

3. Quenching. After the workpiece is heated and insulated, it is quickly cooled in a quenching medium such as water, oil or other inorganic salts and organic aqueous solutions. After quenching, the steel becomes hard, but at the same time brittle.

4. Tempering. In order to reduce the brittleness of the steel, the quenched steel is kept warm for a long time at an appropriate temperature higher than room temperature and lower than 710, and then cold-cracked.

The relationship between annealing, normalizing, quenching, and tempering:

Annealing, normalizing, quenching and tempering are the "four fires" in the overall heat treatment, in which quenching and tempering are closely related, often used together, and one is indispensable. <>

Quenching is a heat treatment method that heats the steel to 30 50 above the critical temperature, keeps warm for a period of time, and then uses water or oil to cool down the workpiece quickly, and the purpose of quenching is to obtain a high hardness martensitic structure. Tempering is to reheat the workpiece to a certain temperature below AC1, keep it warm for a period of time, and then take it out to cool it down in a certain way.

Annealing heats the workpiece to the appropriate temperature, adopts different holding times according to the material and the size of the workpiece, and then undergoes slow cooling (the slowest cooling rate) in order to make the internal structure of the metal reach or close to equilibrium, obtain good process properties and usability, or prepare the structure for further quenching.

The purpose of quenching is to make the supercooled austenite carry out martensite or bainite transformation to obtain martensite or bainite structure, and then cooperate with tempering at different temperatures to greatly improve the rigidity, hardness, wear resistance, fatigue strength and toughness of steel, so as to meet the different requirements of various mechanical parts and tools.

It can also meet the special physical and chemical properties of some special steels such as ferromagnetism and corrosion resistance through quenching. A metal heat treatment process in which a metal workpiece is heated to an appropriate temperature and held for a period of time, followed by a rapid cooling by immersion in a quenching medium. Commonly used quenching media are brine, water, mineral oil, air, etc.

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

Annealing: The process of heating and holding steel and slowly cooling it to room temperature to obtain an approximate equilibrium structure.

Tempering: The process of heating and insulating the steel and cooling it to room temperature at a certain cooling rate, which is generally used in combination with quenching to improve the performance of the workpiece.

Quenching: The process of quickly cooling to room temperature after heating and keeping warm. Rapid cooling to obtain martensitic tissue. The quenching medium used is water, oil, salt, etc.

Normalizing: The process of heating and insulating steel and then naturally cooling it to room temperature in the air. To obtain an approximate equilibrium structure, certain steel grades can be used with annealing.

The difference between the four fires is the way they are cooled.