Valued for its strength and versatility, steel is the most widely used material in the infrastructure, construction, and automotive industries.

While steel in its standard form is strong, hardened steel is more durable and resistant to wear, making it more suitable for heavy-duty applications. For this reason, steel often requires a specialized hardening process to enhance its hardness and strength.

Northern Heat Treat is an ISO 9001:2015-certified metal treatment company that offers services in case hardening, through hardening, flame hardening, and more. Learn more about each type of steel hardening process we provide for our commercial and industrial clients.

What Is Steel Hardening?

Steel hardening improves the hardness and strength of steel alloys. The process involves heating the steel above its austenitizing temperature and quickly quenching it to transform it into stronger, harder martensite steel. After quenching, the next step is tempering down the material to a desired strength level and hardness. This reheats the metal to a lower sub-critical temperature, which increases toughness and ductility.

Types of Steel Hardening

There are three main types of steel hardening that Northern Heat offers: case hardening, through hardening, and flame hardening.

Case Hardening

Also known as case carburization, case hardening involves hardening the outer surface of the steel while keeping the ductility and hardness of the interior the same. This process is usually performed on low-carbon, softer steels that require strengthening.

One of the standard industrial processes for case hardening is flame hardening, which involves heating the surface to extremely high temperatures and then cooling the metal rapidly.

Hardening the outer surface is more efficient than hardening the entire metal, resulting in considerable cost savings. This hardening technique is essential for manufacturing parts that must resist abrasion but be able to absorb impacts without fracturing. These components include gears, pins, rods, camshafts, fasteners, cooking utensils, and tools that encounter a lot of wear and tear.

Through Hardening

Through hardening is the process of strengthening and hardening the entire cross-section of the steel, not just the outer layer. It involves heating the steel, quenching it rapidly in oil or water, and reheating it to reduce surface brittleness. Some applications of through hardening include:

  • Automobile components
  • Hand tools: screwdrivers, hammers
  • Load-bearing parts: chains, brackets, bolts, nuts, axles, springs, bearings

Flame Hardening

Like case hardening, this process strengthens steel by heating the outer layer to very high temperatures. Flame hardening is a specific type of hardening that utilizes a flame in an industrial furnace to harden the metal. Once it reaches about 850 °C, the steel is quenched with water or a synthetic substance, which quickly hardens the surface to a depth of 1 to 10 mm. Typical flame-hardened products include blades, gears, wear plates, hand saws, cams, and certain automotive components.

Steel Hardening at Northern Heat Treat Ltd.

At Northern Heat Treat Ltd., we specialize in various steel treatment services, including air hardening, case hardening, induction hardening, through hardening, flame hardening, and tool steel heat treatment. Our metal hardening services increase wear resistance, strength, and hardness. We pride ourselves on our ability to process very high-capacity induction orders, thanks to our 16 induction scanners and skilled team of employees with four generations of hands-on experience.

Contact us to learn more about our capabilities or to discuss your specific heat treating needs.

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