What types of steel exist and how to process it

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Without the discovery of steel, its properties and processing methods, modern civilization would not exist. Since ancient times, some types of steel have been known that were used for the production of weapons and tools. With the development of metallurgy and metalworking technology, this material began to be used in almost every field of human activity.

Classification by chemical composition

The alloy of iron with carbon, the content of the latter in which does not exceed 2%, is called steel. Its main types are classified primarily by the level of carbon content:

• low carbon;
• medium carbon;
• high carbon.

The first form of the named component contains no more than 0.25%. In medium-carbon steels, its content lies in the range of 0.25-0.6%, and high-carbon steels are distinguished by a concentration above 0.6%.

Steel alloying

The original raw materials for steelmaking already contain some impurities. Most of them are harmful, but there are those thatimprove the properties of the final product. Over time, it was found that some additives significantly change the basic physical and chemical properties of the described alloy. So, the alloying process was discovered. And today, the types and properties of steel with alloying are a priority in the research of metallurgical laboratories and institutes.

According to the concentration of useful impurities, these steels are divided into three groups:

• low-alloyed (impurities up to 2.5%);
• medium-alloyed (alloying elements from 2.5 to 10%);
• highly alloyed (more than 10% alloying).

Classification by purpose

Depending on the production method, chemical composition and the amount of alloying elements, the following types of steel are distinguished:

• structural;
• instrumental;
• with special physical properties;
• with special chemical qualities.

The structural type is the most massive, such alloys are used in the manufacture of most engineering products and in construction.

Tools are high-carbon, high hardness, but also brittle. They are used in the manufacture of various instruments - from surgical to metal-cutting. Hence the name of this type of steel.

For special cases in production, alloys with given physical characteristics are needed:low coefficient of linear expansion, high magnetization ability, etc. These types of steel belong to the class with special physical properties.

Alloys with given chemical qualities are the last type on our list. Some of them are resistant to corrosion, others are heat-resistant, and there are materials with increased chemical resistance.

Classification by the level of harmful impurities

The most common impurities that degrade the properties of steel are sulfur and phosphorus. In alloys of ordinary quality, sulfur content up to 0.06% and phosphorus up to 0.07% is allowed. Steels belonging to the high-quality group contain no more than 0.035% of each of the harmful elements, and high-quality steels - no more than 0.025%. In especially high-quality steels, the level of sulfur impurities is not more than 0.015%, and the phosphorus content is allowed up to 0.025%.

Steel Processing Methods

According to the degree of heating, processing is hot and cold. In the first case, the alloy is heated to the stage of austenite formation, but below the melting point. The steel becomes soft and can be reshaped. The cold type of steel processing is carried out under normal conditions.

According to the type of impact, two main types of processing are divided: pressure and cutting. The first type includes forging, rolling, drawing, stamping and pressing.

The second type of processing includes the following work: turning, drilling, milling. But there is also coldstamping, as well as cold forging, which received a separate name - "hardening".

The latest developments in cold working of steel based on the theory of fluidity of metals allow you to significantly change the shape and size of the original workpiece without heating and with the help of volumetric pressure. The steel is loaded until it reaches a yield state and is "handy" for machining. This method is relevant for some alloys that change their physical, chemical or strength characteristics when heated.