Bearing steel is the steel used to manufacture ball bearings, rollers, and bearing rings. Bearing steel has high and uniform hardness and wear resistance, as well as high elastic limit. The requirements for the uniformity of chemical composition, content and distribution of non-metallic inclusions, and distribution of carbides in bearing steel are very strict, making it one of the most demanding steel grades in all steel production. In 1976, the International Organization for Standardization (ISO) included some common bearing steel grades in international standards, dividing bearing steel into four categories: fully quenched bearing steel, surface hardened bearing steel, stainless bearing steel, and high-temperature bearing steel, totaling 17 steel grades.

Medium carbon steel has good hot working and cutting performance, but poor welding performance. Strength and hardness are higher than low carbon steel, while plasticity and toughness are lower than low carbon steel. Cold rolled or cold drawn materials can be used directly without heat treatment, or they can be used after heat treatment. The quenched and tempered medium carbon steel has good comprehensive mechanical properties. The highest achievable hardness is approximately HRC55 (HB538), with a σ b of 600-1100MPa. So among various applications with moderate strength, medium carbon steel is the most widely used, not only as a building material, but also extensively used in the manufacture of various mechanical parts.

Easy cutting steel refers to alloy steel in which a certain amount of one or more easy cutting elements such as sulfur, phosphorus, lead, calcium, selenium, tellurium, etc. are added to the steel to improve its machinability. With the automation, high speed, and precision of cutting processing, it is very important for steel to have good machinability. This type of steel is mainly used for processing on automatic cutting machines and therefore also belongs to specialized steel.

There are two types of wear-resistant steel bars: one is hot-rolled round steel; Another type is quenched and tempered heat-treated steel bars. The matrix structure obtained by heat treatment of hot-rolled round steel is mainly bainite wear-resistant steel bars; Wear resistant steel bars are widely used in industries such as metallurgy and mining, cement and building materials, thermal power generation, flue gas desulfurization, magnetic materials, chemical industry, coal water slurry, pellet ore, slag, ultrafine powder, fly ash, calcium carbonate, quartz sand, etc.

Adding other alloying elements besides iron and carbon to steel is called alloy steel. Iron carbon alloy composed of adding an appropriate amount of one or more alloying elements to ordinary carbon steel. By adding different elements and adopting appropriate processing techniques, special properties such as high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance, high temperature resistance, and non-magnetic properties can be obtained.

Round steel is divided into three types: hot rolled, forged and cold drawn. The specifications of hot-rolled round steel are 5.5-250 mm. Among them: small round steel of 5.5-25 mm is mostly supplied in straight strips and bundles, and is commonly used as steel bars, bolts and various mechanical parts; round steel larger than 25 mm is mainly used to manufacture mechanical parts and seamless steel pipe blanks. wait.