The smelting of steels and alloys: production methods and technological process

The process of producing steels and precision alloys is a complex sequence of operations aimed at obtaining high-quality materials from raw materials. There are several smelting technologies, each of which has its own characteristics, advantages and applications. Let's consider the basic methods alloy production and steels and their key differences.

The open-hearth method

The open-hearth smelting method, also known as the open open-hearth process, was developed in 1864 by French metallurgist Pierre Martin. The engineer used the principle of heat recovery, previously discovered by K. C. Siemens, which made it possible to obtain a temperature sufficient to melt iron ore into steel.

The open-hearth smelting process includes several stages:

1. Preparation of raw materials. Iron ore with the necessary alloying additives is placed in a large mine. Coal and coke are also added there, which serve as sources carbon — one of the main components in steel production.
2. Pre-firing. The mixture of ore and carbon is heated for several hours. The result is cast iron. If the open-hearth furnace is located separately from the blast furnace, cast iron billets are cast for subsequent processing.
3. Melting in an open-hearth furnace. The cast iron obtained at the pre-roasting stage is transferred to an open-hearth furnace. The furnace has a special anti-reactive material that helps remove impurities from cast iron. When the workpiece is heated, the impurities oxidize and turn into slag. Excess carbon is removed by purging the melt with hot air.
4. Casting of workpieces. After the slag is removed and the required carbon level is reached, melting is stopped. From the open-hearth furnace, molten steel, which has a high temperature, enters the bucket through a special hole, from where it is poured into molds. To obtain semi-finished products of the desired configuration and structure, the finished material is rolled, forged or other processing methods.

The open-hearth method of smelting quickly became popular and made it possible to significantly increase steel production. Due to its efficiency, time savings and the ability to control the quality of the alloy, it has gained significant advantages over the traditional method, such as precipitation. However, with the development of the metallurgical industry, new technologies have gradually replaced the open-hearth method: at present, this method is hardly used in production.

Oxygen converter method

This is one of the most common and effective methods of industrial steelmaking. Its essence is to use oxygen to oxidize impurities and turn them into free gases, as well as to remove excess carbon from the melt. The result is high-quality, low-content steel impurities.

The oxygen-converter smelting process consists of the following steps:

1. Iron smelting. Slag-forming materials are loaded into the metallurgical converter. Oxygenated air is then supplied under high pressure, which leads to oxidation of impurities. The reaction releases a large amount of heat that is sufficient to melt iron.
2. Alloying steel. To control the chemical composition and content of impurities, samples are regularly taken from the melt for analysis. To give steel the required properties, if necessary, it is added to the melt alloying additives.
3. Slag removal. As a result of the oxidation of impurities, slag is formed, which is removed using special mechanisms. In the future, slag can be used as a useful product, for example, in construction.

The oxygen-converter method makes it possible to smelt different grades of steel for different purposes. It is considered one of the most effective methods because it allows you to control the process, as well as maximize the use of waste and reduce emissions of harmful substances. In addition, it does not require additional sources of thermal energy, since the heat released during the oxidation of impurities is sufficient to melt the raw materials.

The main drawback of the presented method is the high equipment costs. However, it does not look so significant in the long run. High productivity, quick melting (50 minutes versus 4—8 hours with the open-hearth method), environmental friendliness and the ability to obtain a high-quality product have made the oxygen-converter method one of the most common methods of steelmaking in modern metallurgy.

Electric steelmaking method

The electric steelmaking method of steel production is based on the use of electrical energy for melting and processing metallurgical raw materials. This method is characterized by high efficiency, flexible production and environmental safety, which makes it attractive for the modern metallurgical industry.

Steel is melted in electric steelmaking furnaces. This equipment is equipped with electrodes that are immersed in molten metal, creating an electric arc. When an electric current passes through electrodes and molten materials, the temperature in the furnace rises to a level sufficient to melt the metal.

The main advantages of the electric steelmaking method are:

• A variety of raw materials. Unlike traditional methods, this process allows the use of various types of raw materials, such as scrap metal, slag and other secondary materials, which contributes to a more efficient use of resources.
• High quality products. The electric steelmaking method makes it possible to obtain materials with various chemical composition and properties, which makes it ideal for the production of a wide range of products, from conventional structural steels to specialized grades used in aerospace, automotive, engineering and other industries.
• Production flexibility. Due to the ability to quickly change the operating modes of the furnace, this method is especially effective in the production of small batches of specialized products. In addition, it makes it possible to achieve a high degree of automation and process control to ensure stable product quality.
• Environmental friendliness. The use of recycled materials instead of traditional raw materials helps to reduce the negative impact on the environment.

Along with the advantages, this method also has a drawback. The equipment requires a significant amount of electricity to operate, which increases production costs. However, despite this, the electric steelmaking process remains an important tool in the modern metallurgical industry. Its flexibility, efficiency and control accuracy chemical composition has made it a key element in the production of various high-quality metal products.

Smelting high-quality steels and precision alloys at PZPS

Due to the peculiarities of its products and high quality requirements, PZPS uses only the electric steelmaking method. It makes it possible to produce a wide range of steels and alloys, including high-quality corrosion-resistant grades: 12X18H10T, 12X18N9, 12X18N9SMR.

Smelting low-alloy carbon steels of the type 60S2A, 65G, 70S2HA is carried out in an open induction furnace with a capacity of 1 ton. This method makes it possible to effectively control the production process and ensure the required quality of alloys.

For the smelting of precision alloys that require precise chemical composition and special physical and mechanical properties, the PZPS uses two vacuum induction furnaces with a capacity of 0.5 tons. They produce:

• soft magnetic alloys, for example 49K2FA, 27KH, 50N, 50NP, 79NM, 81 NM;
• alloys with a given elasticity value, for example, 40KHNM, 36NHTYU, 17HNGT (EI 814);
• alloys with a predetermined temperature coefficient of linear expansion, for example, 29NK, 36N, 42N.

In the near future, an electric slag remelting unit will be put into operation at the PZPS. The introduction of the new technology will make it possible to more accurately control the chemical composition of materials and the melting point, as well as to completely eliminate the presence of gas and non-metallic inclusions in steels and alloys. In addition, electroslag remelting is highly environmentally friendly, as it does not require the use of coal coke and other polluting materials, which makes it possible to reduce emissions of harmful substances into the environment.

For questions about purchasing precision alloys and steels, please call +7 812 740-76-55 or write on the site. Our specialists will contact you as soon as possible and tell you in detail about manufactured products.

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