Many people know that steel is a product obtainedin the process of melting other elements. But which ones? What is included in the steel? Today, this substance is a deformable iron alloy with carbon (its amount is 2.14%), as well as a small fraction of other elements.
General information
It is worth noting that steel is an alloy that has exactly up to 2.14% of carbon in its composition. The alloy, in which there is more than 2.14% carbon, is already called cast iron.
It is known that the composition of carbon steel and ordinarynot the same. If carbon and other alloying (improving) components are included in the usual substrate, then there are no alloying elements in the carbon product. If we talk about alloy steel, its composition is much richer. In order to improve the performance characteristics of this material, elements such as Cr, Ni, Mo, Wo, V, Al, B, Ti, etc. are added to it. It is important to note that the best properties of this substance are provided precisely by adding doped complexes. and not one or two substances.
Classification
The classification of the material we are considering can be classified according to several indicators:
- The first indicator is the chemical composition of the steel.
- The second is the microstructure, which is also very important.
- Of course, they have become different in quality and method of production.
- Also, each type of steel has its own use.
In more detail the structure can be considered on the example of chemical composition. On this basis, two more types are distinguished - these are alloyed and carbon steels.
Among carbon steels there are threevarieties, the main difference is the quantitative content of carbon. If the substance contains less than 0.3% carbon, then it is classified as low carbon. The content of this substance in the region from 0.3% to 0.7% converts the final product to the category of medium carbon steels. If the alloy contains more than 0.7% carbon, the steel belongs to the category of high carbon.
With alloyed steels things are aboutalso. If the composition of the material contains less than 2.5% of alloying elements, then it is considered low-alloyed, from 2.5% to 10% - moderately doped, and from 10% and higher - high-alloyed.
Microstructure
The microstructure of the steel differs depending onher condition. If the alloy is annealed, then its structure will be divided into carbide, ferritic, austenitic, and so on. With a normalized microstructure of a substance, the product can be pearlitic, martensitic, or austenitic.
Состав и свойства стали определяют принадлежность product to one of these three classes. The least alloyed and carbon steels are the pearlite class, the middle ones are martensitic, and the high content of alloying elements or carbon converts them to the category of austenitic steels.
Production and quality
It is important to note that an alloy such as steel caninclude some negative elements, the large content of which affects the performance of the product. These substances include sulfur and phosphorus. Depending on the content of these two elements, the composition and types of steel are divided into the following four categories:
- Ordinary steel. This alloy is of ordinary quality, contains up to 0.06% sulfur and up to 0.07% phosphorus.
- Quality. The content of the above substances in these steels is reduced to 0.04% sulfur and 0.035% phosphorus.
- High quality. They contain only up to 0.025% of both sulfur and phosphorus.
- The highest quality is assigned to the alloy if the percentage of sulfur content is not more than 0.015, and that of phosphorus is not more than 0.025%.
If we talk about the production process of privatethe alloy, it is most often produced in open-hearth furnaces or in Besmer, Thomas converters. This product is bottled into large ingots. It is important to understand that the composition of steel, its structure, as well as quality characteristics and properties are determined precisely by the method of its manufacture.
Open-hearth furnaces are also used to produce high-quality steel, but the smelting process here is made more stringent in order to get a quality product.
Smelting high-quality steelcarried out only in electric furnaces. This is explained by the fact that the use of this type of industrial equipment guarantees an almost minimal content of non-metallic additives, that is, it reduces the percentage ratio of sulfur and phosphorus.
Для того чтобы получить сплав особо высокого qualities, resort to the method of electroslag remelting. Production of this product is possible only in electric furnaces. After the end of the manufacturing process, these steels are always obtained only doped.
Types of alloys for use
Naturally, the change in the composition of steelaffects the performance of this material, and therefore changes the scope of its use. There are structural steels that can be used in construction, cold forming, and can also be cemented, improved, high-strength, and so on.
If we talk about building steels, then to themmost often include medium-carbon and low-alloyed alloys. Since they are used mainly for the construction of buildings, the most important characteristic for them is good weldability. Of the cemented steel is often made various parts, the main purpose of which is to work in conditions of surface wear and dynamic load.
Other steel
Other types of steel include improved.This type of alloy is used only after heat treatment. The alloy is subjected to high temperatures for quenching, and then subjected to tempering in any environment.
The type of high-strength steels are those in whichafter the selection of the chemical composition, as well as after the passage of heat treatment, the strength reaches almost the maximum, that is, approximately twice as much as the usual type of this product.
You can also select spring steel. This is an alloy that, as a result of its production, has obtained the best qualities in terms of elasticity, resistance to loads, as well as fatigue.
Stainless steel composition
Stainless steel is a type of alloyed.Its main property is high corrosion resistance, which is achieved by adding a component such as chromium to the alloy. In some situations, nickel, vanadium or manganese can be used instead of chromium. It is worth noting that when the material is smelted and the necessary elements are added, it can obtain the properties of one of three grades of stainless steel.
Состав этих видов сплава, конечно же, отличается.Conventional alloys with enhanced corrosion resistance 08 X 13 and 12 X 13 are considered to be the simplest ones. The following two types of this corrosion-resistant alloy should have high resistance not only at normal but also at elevated temperatures.
