Since ancient times, man used the procedure of hardening of metal products, which were necessary for him in everyday life. Whether it was cold steel or implements for agricultural work - everything required increased strength. Therefore, people need to invent such a process, as a result of which the metal would become stronger and harder, and its ductility would decrease. And a method of processing metal products was found. Steel hardening is his name. To acquire the necessary qualities, the metal undergoes heating and subsequent cooling during the hardening process.
When stainless steel appeared, there was a need to improve the methods and methods by which metal was processed. Heat treatment even began to develop in a new way, thanks to which today the hardening of steel (stainless) makes it possible to obtain new materials of higher quality.
Martensitic stainless steel is the type of steel to which the quenching process is mainly applied. Its usual state is increased hardness, but it differs in that it is prone to the manifestation of fragility. The use of heat treatment with quick tempering increases the viscosity coefficient, which characterizes this type of steel as one of the most popular metals.
In working with stainless steel, the following types of hardening are distinguished - this is the global view, when the product is fully heated, and the local one, where partial hardening of those areas is applied. In addition, in a process such as steel hardening, various cooling techniques are used. It directly depends on what brand the stainless steel has. Basically, alkali oils and salts are used for these purposes. Water is rarely used as a cooling medium.
Depending on the shape of the product, as well as the grade of the metal, various methods of hardening steel are also applied to it. There are isothermal step hardening and self-tempering hardening.
The main process parameters are heating (temperature) and cooling (speed). Moreover, the speed with which the steel will be cooled, being heated to the desired temperature, will affect the results of hardening itself. The main technical problem of the process is the choice of the optimal temperature due to the fact that during overheating, the stainless steel can lose hydrocarbon, which will lead to a decrease in its strength. In order to avoid residual stress in the internal structure of hardened metal products, additional mechanical processing methods should be applied. For example, phased cooling, where the temperature drop will be gradual. This hardening method is good for making those workpieces that are designed to produce heavy-duty tools.
There is also surface hardening of steel. It does not take much time, unlike chemical-thermal treatment, which allows you to automate the process. With this method of performing the hardening process, it will be necessary to manufacture your own inductor and select your processing mode for each individual part. Surface hardening is suitable for the production of parts of one type (mass production), for example, in the automotive industry.
Thus, in order to obtain high-quality metal products that would possess a combination of strength, toughness and ductility in the required proportions, it is necessary to apply a unique process to steel products called “steel hardening”. And although stainless steel is one of the best materials of our time, nevertheless, technology to improve its quality came to us from ancient times.