Heat treatment of steel can be produced in various ways.Experts distinguish between the following options:
1. Firing.
2. Normalization.
3. Hardening.
4. Vacation.
Heat treatment of steel is heated by firing the product to a temperature of 840 to 900 degrees.At this temperature, exposure is carried out for at least two hours, cooling occurs in the furnace.
steel processing in this way is used in the manufacture of products already tempered or when the need for a new product as a result of temper failed past.In unfired detail in subsequent temperature influence can form cracks that will lead to heterogeneity in the structure of metal.This, in turn, considerably worsen the quality of the product.
for firing small parts used massive steel Glowing staffs with whom they and cooled.In some cases, heat is used acetylene torch.For the gradual cooling of the product, the burner is gradually moving away from him.
steel by thermal treatment is a normalization parts heating to the desired temperature and cooling them in air.
Tempering is a rapid heating and cooling.This heat treatment is used for carbon steel and certain types of metal alloy.As a result of such exposure changes the crystal lattice of the material - it acquires a higher corrosion resistance and hardness.When the content of carbon in the steel up to 0.3% tempering is not carried out.The heating temperature is selected depending on the brand of metal.Exceeding the maximum allowable temperature ("perezhig") will result in the loss of its steel properties.The result is a permanent marriage.
perezhiga to prevent small parts used preheated support (headquarters).Rapid cooling of the product provides a solid temper.The result may be formed significant internal stresses in some cases, even cracks.However, slow cooling required hardness temper may not be possible.
as cooling medium water is used, oil, air or an aqueous solution.Salt (plain), nitrate or sodium hydroxide are added to the coolers are able to rapidly cool down.In order to reduce the cooling rate in water is added a solution of soap, water glass, an oil emulsion, milk of lime and other components.
The sequential hardening few articles used a large jar or frequently change the water.In this case, provided the uniform hardening.
sufficiently rapid and uniform cooling of the steel occurs in 8-12-year-percent solution of common salt and water, or sodium hydroxide at 20 degrees.
Leave a heating parts to a certain temperature, endurance and rapid cooling.This processing method is used after cooling in the hardening product for reducing brittleness and partially hardness.There are three types of holiday: high, low and medium.The most common type of treatment is low.Thus, when heated to 170 degrees internal stress is removed the product without changing the material hardness.
separate species is chemical-heat treatment of steel.This process combines the effect of temperature and saturation of the surface of the metal or the other element.This treatment makes it possible to change the chemical composition, the properties and microstructure of the surface layers of the material.
Chemical-thermal effect include nitriding, carburizing, aluminizing, cyanidation, siliconizing and other methods.
