What are the classifications of heat treatment of steel, and what are the heat treatment of steel

Normalizing, annealing, quenching, tempering.

First, according to the process method to divide:

1) Integral heat treatment (annealing, normalizing, quenching, tempering);

2) Surface heat treatment (flame heating surface quenching, induction heating surface quenching, laser heating surface quenching, etc.);

3) Chemical heat treatment (carburizing, nitriding, other elements, etc.).

Second, according to the role of heat treatment in the processing of parts:

1) Pre-heat treatment (annealing, normalizing): an intermediate process before machining of mechanical parts, in order to improve the cutting performance and prepare for the follow-up organization.

2) Final heat treatment (quenching, tempering): heat treatment to obtain the final use performance of the part.

Steel: Steel is a general term for iron-carbon alloys with a mass percentage of carbon between to. The chemical composition of steel can vary greatly, and steel that contains only carbon elements is called carbon steel (carbon steel) or ordinary steel; In actual production, steel often contains different alloying elements depending on the application, such as:

Manganese, nickel, vanadium, and many more. The application and research of steel has a long history, but until the invention of the Bayesr steelmaking method in the 19th century, the production of steel was a costly and inefficient work. Today, steel is one of the most used materials in the world due to its inexpensive, reliable properties, and is an indispensable ingredient in the construction, manufacturing and daily lives of people.

It can be said that steel is the material basis of modern society.

Annealing: The process of heating the workpiece to a temperature below or above AC1, holding it for a certain period of time, and then cooling with the furnace to obtain a balanced structure. Normalize:

The process of heating the steel to above AC3 or ACCM, cooling it in the air after heat preservation to obtain a fine flake of pearlite, the normalized granular pearlite structure is finer than the annealed. Quenching: After heating the steel to AC1 or AC3 for a certain period of time, it is rapidly cooled (usually greater than the critical cooling rate vc) to obtain a heat treatment process for martensitic structure.

1. Annealing: The process of heating the workpiece to a temperature below or above AC1, holding it for a certain time, and then cooling with the furnace to obtain a balanced structure.

2. Normalizing: the process of heating the steel to above AC3 or ACCM, cooling it in the air after heat preservation to obtain fine flakes of pearlite, and the normalized granular pearlite structure is finer than that of annealing.

3. Quenching: After heating the steel to AC1 or AC3 for a certain period of time, it is quickly cooled (usually greater than the critical cooling rate VC) to obtain the heat treatment process of martensitic structure.

4. Tempering: Reheating the quenched parts to a certain temperature below the critical point A1 for heating and insulation, which is a heat treatment process in which the quenched Yawen structure is transformed into a stable tempering structure and cooled to room temperature at an appropriate cooling rate.

There are four basic processes for the overall heat treatment of steel: annealing, normalizing, quenching and tempering.

1. Annealing: The process of heating the workpiece to a temperature below or above AC1, holding it for a certain period of time, and then cooling with the furnace to obtain a balanced structure. Classification: complete annealing, incomplete annealing, spheroidization annealing, diffusion annealing, recrystallization annealing and stress relief annealing.

2. Normalizing: The process of heating steel above AC3 or ACCM, cooling it in air after heat preservation to obtain fine flake pearlite. Difference from annealing:

1. The cooling rate is faster than that of annealing 2, the normalized and annealed tissues are P class structures, the normalized state is pseudo-P, and the annealed state is the equilibrium structure 3The normalized granular pearlite structure is finer than the annealed one.

3. Quenching: After heating the steel to AC1 or AC3 for a certain period of time, it is quickly cooled (usually greater than the critical cooling rate vc) to obtain a heat treatment process of martensitic (or lower bainite) structure. Necessary conditions for quenching:

1. The steel must be heated to above AC1 or AC3 for a certain period of time to obtain a structure 2, and the cooling rate must be greater than the critical cooling rate VC to avoid a high temperature decomposition 3, and the martensite (or lower bainite) structure is obtained, which is the essence of quenching.

4. Tempering: Reheating the quenched parts to a certain temperature below the critical point A1 for heating and insulation, which is a heat treatment process in which the quenching Yawen slag number structure is transformed into a stable tempering structure and cooled to room temperature at an appropriate cooling rate. It is divided into low temperature tempering, medium temperature tempering, and high temperature tempering.

The metal heat treatment process can be roughly divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment. Depending on the heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. Different heat treatment processes for the same metal, such as extremities, can obtain different tissues and thus have different properties.

Steel is the most widely used metal in industry, and the microstructure of steel is also the most complex, so there are many kinds of steel heat treatment processes. Integral heat treatment is a metal heat treatment process that heats the workpiece as a whole, and then cools it at an appropriate rate to obtain the required metallographic structure, and starves the bridge to change its overall mechanical properties. There are four basic processes for the overall heat treatment of steel: annealing, normalizing, quenching and tempering.

Summary. Steel is an alloy with iron and carbon as the main components, and its carbon content is generally less than . Steel is an extremely important metal material in economic construction.

According to the chemical composition, steel is divided into two categories: carbon steel (referred to as carbon steel) and alloy steel. Carbon steel is an alloy obtained by pig iron smelting, in addition to iron and carbon as its main components, it also contains a small amount of manganese, silicon, sulfur, phosphorus and other impurities. Carbon steel has certain mechanical properties, good process properties, and is cheap.

As a result, carbon steel has gained a wide range of applications. However, with the rapid development of modern industry and science and technology, the performance of carbon steel can no longer fully meet the needs, so people have developed various alloy steels. Alloy steel is a multi-alloy obtained by purposefully adding certain elements (called alloying elements) to carbon steel.

Compared with carbon steel, the performance of alloy steel has been significantly improved, so it is increasingly widely used.

Steel is an alloy with iron and carbon as the main components, and its carbon content is generally less than . Steel is an extremely important metal material in economic construction. According to the chemical composition, steel is divided into two categories: carbon steel (referred to as carbon steel) and alloy steel.

Carbon steel is an alloy obtained by smelting pig iron, in addition to iron and carbon as its main components, it also contains a small amount of manganese, silicon, sulfur, phosphorus and other impurities. Carbon steel has certain mechanical properties, and has good process performance, and is cheap. As a result, carbon steel has gained a wide range of applications.

However, with the rapid development of modern industry and science and technology, the performance of carbon steel can no longer fully meet the needs, so people have developed various alloy steels. Alloy steel is a multi-alloy obtained by purposefully adding certain elements (called alloying elements) to carbon steel. Compared with carbon steel, the performance of alloy steel has been significantly improved, so it is increasingly widely used.

Due to the wide variety of steel products, in order to facilitate production, storage, selection and research, steel must be classified. According to the use, chemical composition and quality of steel, steel can be divided into many categories: (1) Classification according to the use of steel can be divided into three categories: structural steel, tool steel, and special permeability steel.