Is there a chemical change in quenching What is the equation

There was a chemical change.

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. Quenching can improve the hardness and wear resistance of metal workpieces, so it is widely used in various tools, molds, measuring tools and parts that require surface wear resistance (such as gears, rolls, carburizing parts, etc.).

The strength, toughness and fatigue strength of the metal can be greatly improved by quenching and tempering at different temperatures, and the combination between these properties (comprehensive mechanical properties) can be obtained to meet different application requirements. In addition, quenching can also make some special properties of steel obtain certain physical and chemical properties, such as quenching to enhance the ferromagnetism of permanent magnet steel, stainless steel to improve its corrosion resistance, etc. The quenching process is mainly used for steel parts.

When commonly used steel is heated above the critical temperature, all or most of the original structure at room temperature will be converted to austenite. The steel is then immersed in water or oil for rapid cooling, and the austenite is transformed into martensite. Martensite hardness is the highest compared to other structures in steel.

The purpose of steel quenching is to convert all or most of its microstructure into martensite, obtain high hardness, and then temper it at the right temperature to make the workpiece have the expected properties. The rapid cooling during quenching will cause internal stress inside the workpiece, and when it is large enough, the workpiece will be twisted and deformed or even cracked. For this purpose, it is necessary to choose a suitable cooling method.

According to the cooling method, the quenching process is divided into four categories: single-liquid quenching, double-medium quenching, martensitic graded quenching and bainite isothermal quenching.

There are chemical changes.

3fe+4h2o＝＝fe3o4+4h2

The quenching "呲呲" is the sound of hydrogen explosion.

It happened, and there is no specific equation to represent this, that is, the molecular structure of the steel has changed slightly.

There are chemical changes, mainly structural, of course there is also partial oxidation of the metal, but if you study quenching, it is mainly a change in the microstructure. For example: Alpha iron, which is transformed between it iron and sigma iron.

There are both physical and chemical changes. Iron and water produce hydrogen and ferric tetroxide.

Quenching changes its internal structure, quenching is to make the supercooled austenite (carbon dissolved in Fe solid solution) non-diffusion co-lattice shear phase into filial martensite (is a supersaturated solid solution of carbon and (or) alloying elements in iron), due to the change of its structure, resulting in a change in physical properties, generally after quenching the hardness, strength will increase, and plasticity, toughness decreases and so on.

Because some chemical reactions have an excess of a reactant, when the reaction is carried out to a certain extent, the target product has been obtained, and if the excess reactant continues to exist, it will further react to form undesirable products, so it needs to be quenched. The principle of quenching is to react with another compound that is more likely to react with the excess compound, thereby removing it from the system.

Quenching means that the reaction does not continue to occur or that the reaction rate is low. Because the concentration of the substrate decreases, the rate of counter-bridging decreases. Or because other substances are introduced to bind to one of the substances in the substrate, the original reaction cannot occur.

In chemical experiments, quenching refers to extinguishing a flame with water or other chemical agents. This is because in chemical experiments, some chemical reagents or substances are flammable, and if they accidentally come into contact with the fire source, they will cause a fire or cause a fire. Therefore, it is necessary to be vigilant at all times during the experiment, and once a flame or heat source is found, quenching measures should be taken immediately to ensure the safety of the experiment.

In addition, quenching can also prevent the toxic gases or harmful substances produced in the experiment from being released into the air through combustion, causing harm to the environment and human health. Therefore, in chemical experiments, quenching is a very important safety measure.

The quenching and tempering of steel is an important and widely used process in the heat treatment process. Quenching can significantly improve the strength and hardness of steel. If it is tempered with different temperatures, the internal stress of quenching can be eliminated (or reduced), and the combination of strength, hardness and toughness can be obtained to meet different requirements.

Therefore, quenching and tempering are two inseparable heat treatment processes.

Quenching is a heat treatment process in which steel is heated above the critical point, and then cooled at a temperature greater than the critical cooling rate (VC) after heat preservation to obtain a martensitic or lower bainite structure.

Tempering is a heat treatment process in which quenched steel is heated to a certain temperature below the A1 point for a certain period of time, and then cooled to room temperature in an appropriate way. It is the next heat treatment process immediately after quenching, which determines the structure and properties of the steel in the use state, and is related to the service life of the workpiece, so it is a key process.

The main purpose of tempering is to reduce or eliminate quenching stress; Ensure the corresponding organizational transformation, so that the size and performance of the workpiece are stable; Improve the thermal and plastic properties of steel, choose different tempering temperatures, and obtain the appropriate combination of hardness, strength, plasticity or toughness to meet the performance requirements of different workpieces.

There are both physical and chemical changes.

For example, when quenching, the volume changes, which belongs to physical changes.

During quenching and tempering, martensite formation and decomposition involve the movement and migration of atoms, and from this point of view, it should be a chemical change.

In general, chemical changes should be the main focus.

For steels with a high carbon content, a high hardness is obtained immediately after quenching, while the plasticity is very low. However, this is not the case for aluminum alloys, after quenching, the strength and hardness do not increase immediately, and the plasticity does not decrease, but increases. However, after this quenched alloy, after a period of time (such as 4 6 days and nights), the strength and hardness will be significantly improved, while the plasticity will be significantly reduced.

The phenomenon that the strength and hardness of aluminum alloy increase significantly with time after quenching is called aging. Aging can occur at room temperature, called natural aging, or it can occur in a certain temperature range higher than room temperature (such as 100 200), which is called artificial aging.