Case hardening steel

This is case-hardened steel

The case hardening process involves thermochemically increasing the carbon content of the surface of a low carbon steel. It is a very widely used surface hardening process. Industrially, the incidence and demand for case hardened steel is so great that it represents one third of all hardening heat treatment.

The result is a combination of a hard surface with strong resilience while maintaining the softness of the steel core. This avoids failures caused by brittleness.

Case hardening works for all types of structural steel, but for best results the steel must be alloyed with nickel, chromium and molybdenum.

For example, pre-hardened steel is used for

• Gears in transmissions
• Shoulders
• Wind turbines
• Components in gearboxes
• Other applications where a high tolerance to shock loading is required.

What are the three phases of case hardening?

• The carbon content is affected. Adding carbon to the furnace atmosphere increases the carbon content of the steel surface. This is done by diffusion, where the carbon penetrates the steel. The depth of carburisation, the zone where the carbon content increases, usually ranges between 0.5 and 2 mm. It is controlled by adjusting temperature, carbon content in the atmosphere and holding time in the furnace. The resulting layer normally has a carbon content of about 0.7 to 0.9%.
• Martensite transformation. After carburising, there is a stage where the steel is rapidly cooled and hardened. This creates a strong Martensite transformation in the carbonised surface layer. The result is an impressive surface hardness, usually between 58 and 65 HRC (Rockwell hardness scale).
• Possible tempering. After case hardening, the steel does not necessarily have to undergo a tempering process. The overall hardness of the base material is controlled by the properties of the selected steel and the size. Tempering reduces the risk of stresses and cracking.

Livallco supplies case hardening steel

In the table you can see our selection of case hardening steels. If you have any questions about the range or applications, you are welcome to contact us. the specialists at Livallco.

Mechanical steel

These steels also belong to the group formerly known as machine steels.

Machine steel is designed to be easily machined in various processes such as cutting, turning, milling and drilling. Nowadays, most steels are designed to improve cutting and machinability. Often alloying elements such as sulphur are added to improve cutability. Machine steel also usually has high strength, meaning it can withstand loads and resist deformation during use. They are also known for their durability and ability to resist wear, which is important in mechanical engineering applications where parts are subject to abrasion and friction.

Machine steel is used in a variety of mechanical engineering applications, including the manufacture of shafts, gears, shock absorbers, piston rods and other critical components of machinery and equipment.