Heat treating is a process used to change the chemical and mechanical properties of wear resistant steel produced in its original form. A common example of this is heating the material to a high temperature, quickly cooling it with water or oil (quenching), and then reheating it at a lower temperature (tempering).

Annealing, normalizing, and stress relieving do not involve any quenching or tempering. Stress relieving is used for both ferrous and non-ferrous alloys, aiming to eliminate internal residual stresses from prior manufacturing processes like machining, cold rolling, and welding.

Normalizing, on the other hand, is selectively applied to engineering steels to either soften, harden, or relieve stress based on their initial condition. The goal is to address the effects of earlier processes such as casting, forging, or rolling by refining the existing structure, enhancing machinability or formability, and meeting final mechanical property requirements in certain product forms.

Meanwhile, annealing primarily aims to reduce material hardness, enabling smoother progress in subsequent manufacturing steps.

Different Types of Treatments

Annealing

Annealing is designed to reduce the steel’s hardness and increase its ductility to reduce cracking. It involves slowly heating wear resistant steel to a certain temperature for a set time and then slowly cooling it in an oven to change its microstructure. This is known as “soak time,” which is usually about one hour per inch of thickness.

Normalizing

Similar to annealing, normalizing is also designed to reduce stresses and increase ductility. The steel is heated to a specific temperature, taken out of the oven, and then cooled to room temperature. Normalizing is more common than annealing because it is less expensive and does not tie up the oven during “soak time,” which could last up to 20 hours.

Stress Relieving

Stress relieving is done after hot rolling, welding, or cutting with heat, all of which build up stresses. In this process, the steel is heated to a temperature just below the critical annealing temperature and then allowed to cool slowly. This results in little or no change to the steel’s properties and is usually applied to low carbon steels.

What Advantages Does It Offer?

Stress relieving, normalizing, and annealing methods prime metals and alloys for subsequent processing or specific service conditions. They enhance machinability, minimize distortion in service, prevent cracking during forming, facilitate subsequent hardening or carburizing with minimal distortion, and improve resistance to corrosive environments.

Which Materials Can Undergo These Processes?

Annealing and stress relieving are applicable to all commercial alloys, while normalizing is limited to specific steels.

Are There Limitations to Treating Wear Resistant Steel?

Stress relieving of carbon or low-alloy steel fabrications is often the final heat treatment applied, necessitating careful consideration to ensure there are no adverse effects on the mechanical properties of the materials.

Stress relieving between machining operations can be conducted on pre-treated material, although the effectiveness may need to be adjusted to prevent any loss of mechanical properties. Certain austenitic stainless steels require rapid cooling following high-temperature stress relief or solution annealing, leading to some level of distortion or reintroduction of residual stresses.

The ability to stress relieve, anneal, or normalize items depends on the equipment capabilities of the heat treater, particularly for larger items where suitable facilities need to be confirmed early in the process.

How Do I Specify Heat Treatment Requirements?

When specifying heat treatment requirements, ensure to include the following details:

  1. Specify the desired process: Stress relieving, normalizing, or annealing. Indicate if bright treatment is necessary or if treatment in air is acceptable.
  2. Provide information about the material: Type, grade, and the standard it complies with. Include composition details and provide relevant certificates if available.
  3. Mention any applicable standards: National, international, or company standards that contain relevant details to be followed.
  4. Describe the existing condition: Details of any prior heat treatments, such as hardening and tempering, solution treatment, or ageing, aimed at establishing mechanical or other properties.
  5. State the required mechanical properties: Specify a range of hardness or tensile strength based on the standard being followed. Note that achieving a specific figure may not be feasible due to external variables.
  6. Specify testing requirements: Indicate the type of testing required, such as hardness (Vickers, Brinell), tensile tests, etc. Mention any special testing locations or sample removal for test pieces.
  7. Outline any additional services needed: Such as straightening (within working limits), cleaning/blasting, laboratory services, or specialized non-destructive testing (NDT) services.

It’s important to discuss any uncertainties or queries with your heat treater before finalizing the specification to ensure accurate and satisfactory heat treatment results.

ENDURA by Titus Steel: The Unique Wear Resistant Steel

ENDURA is a unique wear resistant steel that does not require annealing, normalizing, or stress relieving. It handles wear eight times greater than mild steel. Because of the heat treatment and quenching in oil rather than water, the microstructure of ENDURA is very homogeneous.

Imagine dropping a bundle of pick-up sticks, creating a jumbled mess. Now, envision laying down each stick neatly in a row beside one another—that’s the microstructure of ENDURA. This organized arrangement reduces tearing, shearing, and gouging of the steel, enhancing its durability and performance.

For more information on the best wear resistant steel for your needs, contact us.