Annealing, quenching and heat treatment case hardening structural steel
To buy at an affordable price of the manufacturer alloyed structural steel, subjected to cementation, offers the company Elektrovek-steel. The supplier guarantees prompt delivery of products to the address specified by the customer.
Heat treatment features
For most cemented steels, a double heat treatment is necessary for the first quenching (normalization) from 850… 900 ° С; Second hardening from 780… 800 ° С; And then tempering at 150… 200 ° C. In the first stage, the recrystallization process improves the core structure, which contains a reduced percentage of carbon, and also removes the cementitic network formed in the surface layer. However, for a layer enriched in carbon, the temperature 850… 900 ° C is too high. Therefore, overheating is eliminated as a result of repeated hardening. At the same time, the required hardness values of the surface layers of steel are achieved. As a result of subsequent release, internal and most residual stresses are removed (for details of complex configuration).
The final structure of the surface layer after heat treatment is fine-grained martensite (in which the carbides are uniformly distributed) and some residual austenite. Core regions are low-carbon martensite and ferrite.
Such a two-stage heat treatment is considered to be the main feature of heat treatment of alloyed steels that have undergone cementation.
The company Electrovek-steel offers to buy at an affordable price of the manufacturer rental of various grades of alloyed low-carbon steels that can be cemented. The supplier ensures timely delivery of products to any point specified by the consumer.
Heat Treatment Modes
They are determined by the method of carburizing. When heat treatment using gaseous steels having a fine-grained structure (characteristic, in particular, for 18KGT steel), hardening is performed immediately after the product is extracted from the cementing furnace. The method of such quenching is simple and economical, since it avoids reheating, but is sometimes accompanied by increased warping of parts, which increases with increasing values of quenching temperatures. At the same time, a significant percentage of residual austenite remains in the final steel structure, which reduces the hardness of the steel. To reduce the residual austenite in the cemented layer, after quenching and tempering, cold treatment or high tempering is performed at 600… 650 ° C (at these temperatures, the residual austenite decomposes).
It is possible to reduce warpage during hardening of cemented alloy steels in two ways:
Hardening in the preheated to a temperature of 160… 180 ° C oil;
Hardening in forging dies (the method is used mainly for forgings of complex shapes).
For cemented parts such as heavy-duty gears, it is important to achieve the necessary strength and hardness of the core of the product. For this purpose, a high tempering is carried out at a temperature of 580… 620 0 С. The hardness of the core is 40… 45 HRC.
Rolled low-carbon steels are offered by the company Electrovek-Steel at economically reasonable prices. The supplier guarantees timely delivery of the products to any point specified by the customer.