Low-alloy steel, properties, technical characteristics, processing features and types of low-alloy alloys

Low-alloy steel It contains alloying elements in small quantities, hence the name. Among the alloying components are chromium, nickel, molybdenum, and others, which impart special properties. Thanks to the above elements, low-alloy steel It gains improved strength, becomes more workable, and is corrosion-resistant, although it remains quite vulnerable to atmospheric influences. The alloy's alloying elements should contain less than 2.5% of the total volume, excluding carbon.

Low-alloy steel grade

Low-alloy steel grade The alloy's chemical composition is indicated by a large number of types and designations. The metal marking technology is structured as follows: the number preceding the letter corresponds to the average carbon content of the steel in hundredths of a percent. The letters, respectively, indicate the name of the alloying element:

• G- manganese;
• C - silicon;
• X- chrome;
• N- nickel, etc.

If the component constitutes less than 0.3% of the total material volume, it is not included in the designation. These steels have better mechanical properties, higher wear resistance, and better weldability than carbon steels, but all these grades require corrosion protection. Low-alloy steel grades 10HSND, 10HSND, and 15HSND steels contain copper and tin alloys and exhibit excellent weather resistance, making them popular for building structures, transmission towers, and other applications. Grades such as 18G2S and 25G2S are used as reinforcement in reinforced concrete structures. Grades 16GS and 09G2S, containing silicon and manganese, are high-strength and very reliable, and are successfully used in the chemical industry. These steels exhibit good ductility, impact toughness, and weldability.

Low alloy steel applications

Low alloy steel applications The range of applications is quite extensive due to a combination of several positive characteristics. For example, the mechanical strength of the steel allows for weight reductions, sometimes down to 30%, through the use of various rolled products. Furthermore, the use of low-alloy steels allows for increased structural reliability and service life, while reducing costs. Thanks to the well-balanced alloying elements, the thickness of the products is significantly reduced, therefore low-alloy steel applications It is used in shipbuilding, main pipelines, bridge construction, and in reinforced concrete plants to ensure the rigidity of reinforced concrete structures, for the manufacture of pressure vessels, mining equipment, earthmoving equipment, etc.

Marking of low-alloy steels

Marking of low-alloy steels has letters and numbers. The letter denotes the alloying element contained, and the number denotes the average content of the element. Example: alloy 18KhGT contains:

• 0.18% C;
• 1% Cr;
• 1% Mn;
• 0,1% Ti.

Low-alloy steel grades may have additional designations:

• P - high-speed steel;
• Ш — ball bearing;
• A - free-cutting steel;
• E – electrical engineering;
• L - obtained by casting.

Processing of low-alloy steel

Processing of low-alloy steel It can be thermally modified to give the alloy increased strength, ductility, low-temperature stability, and good corrosion resistance. For example, oil and gas pipeline pipes require special strength properties. Low alloy processing steel It can be mechanical-thermal. In this process, the workpiece undergoes cold forging followed by annealing. Forging achieves the required fine grain and nanocrystalline state, while annealing initiates the necessary recrystallization processes, creating a dispersed structure. This procedure allows for the correction of even the smallest defects in the alloy's microstructure and increases its resistance to brittle fracture.