What is the essence of heat treatment process preparation?

Obtain the ideal metallographic structure.

Common heat treatment processes.

There are normalizing, annealing, solid solution, aging, quenching.

Tempering, annealing, carburizing, nitriding, quenching and tempering, spheroidization, brazing, etc

1. Normalizing: Heat the steel or steel parts to an appropriate temperature above the critical point AC3 or ACM for a certain period of time and then cool it in the air to obtain a heat treatment process of pearlite structure.

2. Annealing: 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.

3. Solution heat treatment: The alloy is heated to a high temperature single-phase zone and maintained at a constant temperature, so that the excess phase is fully dissolved into the solid solution, and then cooled quickly to obtain the heat treatment process of supersaturated solid solution.

4. Aging: The phenomenon that the performance of the alloy changes with time when it is placed at room temperature or slightly higher than room temperature after solution heat treatment or cold plastic deformation.

5. Solution treatment.

The various phases in the alloy are fully dissolved, the solid solution is strengthened, the toughness and corrosion resistance are improved, the stress is eliminated and softened, so that the processing can be continued.

6. Aging treatment: heat and keep warm at the temperature of the precipitated phase of the strengthened phase, so that the precipitated precipitation of the strengthened phase can be hardened and the strength can be improved.

7. Quenching: After austenitization of the steel, it is cooled at an appropriate cooling rate, so that martensite occurs in all or a certain range of the workpiece in the cross-section.

and other unstable organizational structures.

Transformed heat treatment process.

8. Tempering: The quenched workpiece is heated to an appropriate temperature below the critical point AC1 for a certain period of time, and then cooled by a method that meets the requirements to obtain the required structure and performance.

9 Carbonitriding of steel: Carbonitriding is the process of infiltrating carbon and nitrogen into the surface layer of steel at the same time. Traditionally, carbonitriding, also known as cyanidation, is widely used in medium-temperature gas carbonitriding and low-temperature gas carbonitriding (i.e., gas soft nitriding).

The main purpose of medium-temperature gas carbonitriding is to improve the hardness, wear resistance and fatigue strength of steel. Low-temperature gas carbonitriding is mainly based on nitriding, and its main purpose is to improve the wear resistance and seizure resistance of steel.

10. Quenching and tempering: It is generally customary to combine quenching and tempering with high temperature tempering heat treatment. Quenching and tempering treatment is widely used in a variety of important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads.

After quenching and tempering treatment, the tempered sostenite structure was obtained, and its mechanical properties were better than that of the normalized sostenite microstructure of the same hardness. Its hardness depends on the high temperature tempering temperature and is related to the tempering stability of the steel and the cross-sectional size of the workpiece, generally between HB200 and 350.

11 Brazing: A heat treatment process in which two workpieces are heated, melted, and bonded together with brazing metal.

The metal heat treatment process can be roughly divided into three categories: overall heat treatment, surface heat treatment and chemical heat treatment.

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

2. Surface heat treatment is a metal heat treatment process that only heats the surface of the workpiece to change the mechanical properties of its surface. In order to only heat the surface of the workpiece and not let too much heat pass into the workpiece, the heat source used must have a high energy density, that is, a large heat energy is given to the workpiece per unit area, so that the surface or local layer of the workpiece can reach high temperature in a short time or instantaneously. The main methods of surface heat treatment are flame quenching and induction heating heat treatment, and the commonly used heat sources are flame such as oxyacetylene or propylene oxide, induced current, laser and electron beam.

3. Chemical heat treatment is a metal heat treatment process that changes the chemical composition, structure and properties of the surface of the workpiece. Chemical heat treatment differs from surface heat treatment in that the latter changes the chemical composition of the surface layer of the workpiece. Chemical heat treatment is to heat the workpiece in a medium (gas, liquid, solid) containing carbon, nitrogen or other alloying elements, and keep it warm for a long time, so that the surface of the workpiece is infiltrated with elements such as carbon, nitrogen, boron and chromium.

After penetrating the elements, other heat treatment processes such as quenching and tempering are sometimes carried out. The main methods of chemical heat treatment are carburizing, nitriding, and metallurgization.

The four most basic heat treatment processes include quenching, tempering, normalizing, and annealing.

Quenching is the quenching of steel after heating it to the right temperature to obtain high hardness and toughness. Tempering is the reheating and holding of steel after quenching to reduce hardness and increase toughness. Normalizing is the heating of steel to a certain temperature and then cooling to room temperature, changing the microstructure of the steel to improve mechanical properties.

Annealing is to heat the steel to a certain temperature and then slowly cool it in the furnace to obtain relatively uniform grains and good processing properties. These four processes are widely used in industrial production and can be used to produce a variety of steel and metal products.

Common metal heat treatment poor material process and its application:

Heat treatment is an indispensable part of the metalworking process, and different processes can obtain different material properties and applications. In addition to quenching, tempering, normalizing, and annealing, there are many other heat treatment processes, such as quenching plus tempering, surface quenching, aging treatment, etc. In industrial production, different metal materials and products need to choose different heat treatment processes to meet the requirements of the use of dust and liquid.

For example, quenching plus tempering is suitable for the manufacture of gears, bearings and other high-strength parts, and aging treatment is suitable for high-strength aluminum alloy materials in aviation, automotive and other fields. <>

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

1. Annealing is to heat the workpiece to an appropriate temperature, adopt different holding times according to the material and the size of the workpiece, and then carry out slow cooling, the purpose is to make the internal structure of the metal reach or close to the equilibrium state, obtain good process performance and use performance, or prepare for further quenching.

2. Normalizing is to heat the workpiece to a suitable temperature and then cool it in the air, the effect of normalizing is similar to annealing, but the structure obtained by changing the plum is finer, which is often used to improve the cutting performance of the material, and is sometimes used for some parts with low requirements as the most cherry final heat treatment.

3. Quenching is to heat and keep the workpiece warm, and then quickly cool it in water, oil or other inorganic salts, organic aqueous solutions and other quenching mediums. After quenching, the steel becomes hard, but at the same time brittle.

4. 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 the room temperature and lower than 710, and then cooled, which is called tempering.

Process characteristics of heat treatment

Heat treatment is one of the important processes in machinery manufacturing, compared with other processing processes, heat treatment generally does not change the shape of the workpiece and the overall chemical composition, but by changing the microstructure inside the workpiece, or changing the chemical composition of the surface of the workpiece, to give or improve the performance of the workpiece. It is characterized by an improvement in the intrinsic quality of the workpiece, which is generally not visible to the naked eye.

In order to make the metal workpiece have the required mechanical, physical and chemical properties, in addition to the reasonable selection of materials and various forming processes, the heat treatment process is often indispensable.

Steel is the most widely used material in the machinery industry, and the micronucleus of steel is complex, which can be controlled by heat treatment, so the heat treatment of steel is the main content of metal heat treatment.

The classification is as follows: 1. According to the role of the hot cavity jujube theory, it is divided into: pre-heat treatment process and final heat treatment process;

2. According to the parts of spring round heat treatment: overall heat treatment process, local heat treatment process;

3. According to the method of heat treatment, it is divided into: annealing process, complete annealing process, incomplete annealing process, spheroidization annealing process, dehydrogenation annealing process, diffusion annealing process, homogenization annealing process, isothermal annealing process, stress relief annealing process, recrystallization annealing process, normalizing process, chemical heat treatment process;

4. According to the classification method of heat treatment parts: spring hot part picking process, bearing heat treatment process.

The classification is as follows: 1. According to the role of Zifeng heat treatment, it is divided into: nuclear height pre-heat treatment process, final heat treatment process;

2. According to the parts of heat treatment: overall heat treatment process, local reform ruler heat treatment process;

3. According to the method of heat treatment, it is divided into: annealing process, complete annealing process, incomplete annealing process, spheroidization annealing process, dehydrogenation annealing process, diffusion annealing process, homogenization annealing process, isothermal annealing process, stress relief annealing process, recrystallization annealing process, normalizing process, chemical heat treatment process;

4. According to the classification method of heat treatment parts: spring heat treatment process, bearing heat treatment process.

Cracking and peeling of nitrogen chemical parts occurs.

1) The decomposition rate of ammonia exceeds 85%, which may occur (2) The surface of the special workpiece is in the decarburization layer before nitriding treatment.

3) The workpiece design has obvious acute angles.

4) When the white layer is too thick.

In Xiamen, you can see the same Anxike heat treatment plant, 501 Fuming Road, Xike Town