Thermal Treatment

Bekaert provides thermal treatment for steel products to alter material properties and make the steel more suitable for your application. Our thermal treatment services include annealing, hardening and tempering.

Annealing

Annealing is a heat treatment that has various effects on steel's properties. At Bekaert, we work with quality equipment for annealing metal. We use hydrogen/nitrogen atmosphere batch annealing bell furnaces for annealing steel and a separate system to meet the higher temperature requirements of stainless steel annealing. We maintain a tight tolerance on temperature control in our furnaces, keeping variation to as little as 2 degrees Fahrenheit.

In general, the annealing process heats steel to an extreme temperature. The heat relaxes the material to make it more malleable and flexible for easier manipulation into a desired shape. The different kinds of annealing include:

• Full: During this process, manufacturers heat steel to 30 degrees Celsius above their transformative temperature and allow the material to cool naturally. This method reduces internal stresses, improves machine workability and creates a fine-grained, microcrystalline structure.
• Isothermal: While full annealing allows the steel to cool, isothermal annealing forcibly cools the material to its lower critical temperature, the degree to which the hold period begins. At that point, the steel grain becomes pearlite and cools slowly.
• Spherical: This annealing process produces globular pearlite by holding the material near the critical temperature and then allowing the material to slowly cool. An even distribution of globular pearlite is created in the material that helps with cold-forming.
• Recrystallization: This intermediate annealing heats steel until its grain becomes uniform. It neutralizes process hardening and residual stress so that multistage cold-working can happen without risk.

Our controlled atmospheric environment prevents oxidation and decarburization and ensures consistent results. The annealing process creates a softer metal that's easier to shape for your intended projects. Our annealed steel products have a bright surface finish that exceeds your specifications. Other advantages include relieved stress, increased ductility and enhanced grain structures.

During the process, we use an even heat distribution and tight temperature control. We choose the process type based on your specifications and preferred results and the metal's type and mass. Though Bekaert does not typically offer annealing as a stand-alone service, we will complete it as part of a comprehensive thermal treatment process.

Hardening and Tempering

Hardening and tempering is a two-step thermal process that strengthens steel for a range of applications. Our hardening and tempering services are valuable to specialty wire applications, such as flexible pipes, rake tines and piston rings. We also provide packaging needs based on project specifications, including:

• Cut-to-length
• Coils on reels
• Coils on cardboard cores

Hardening is effectively the opposite of annealing — where annealing makes steel softer, hardening makes the metal stronger. The hardening thermal treatment makes the steel stronger and provides a uniform microstructure. We heat steel to a given transformation temperature and then quickly and uniformly quench the material in brine, oil or water. While the cooling process for steel is rapid, steel alloys require a slower cooling rate.

With our advanced process control system, we offer consistent mechanical and physical properties and uniform microstructures for all thermal-treated steel. Bekaert will use the correct quenching substance and hardening processes based on your steel composition and other factors to achieve the best results.

The hardening process can create high internal stress, low ductility and brittleness in the steel. When the material is tempered, this thermal process can provide the desired tensile strength and ductility required for your application while relieving or removing internal stress.

Our tempering process requires heating the steel, maintaining the temperature and cooling the steel by air. This process helps you achieve the desired physical properties in your steel product.