Being a precision metalworker or being in a position where you need to understand what separates different processes from each other can be daunting. There are so many operations, processes, and terms to know, how can you learn all of them? The best place to look is to the experts: people who live and breathe the industry. So, if you find yourself wondering annealing vs normalizing? Which is the right one for me? you’re in the right place.
This blog will explore annealing and normalizing. Along the way, we’ll explain how each works, cover the benefits they offer, and provide examples of each being used in the real world. Ready? Let’s get going!
Heat Treatment
Both annealing and normalizing are heat treating processes.
All metals have different properties—which is one of the most important considerations we need to make when we put these metals to use.
Heat treatment is an essential step in the manufacturing process. It improves the metal depending on what you need it to do. For example, we can make metals stronger, harder, more durable, or more ductile.
Heating and Soaking
In general, the heat treatment process heats the metal (either in a pure form or as an alloy) to a specific temperature for the material in question. Sometimes, we need to heat the metal to 2400°F!
Once we get the metal to the needed temperature, it is held at that temperature for a predetermined period of time, called the “soak time.” As the metal is heated, its internal microstructure changes, and so do its properties. The longer the metal “soaks” in the heat, the more these properties change. Therefore, it’s important to heat the metal to the right temperature and soak it for the right amount of time.
Quenching and Cooling
After the metal has been heated, it’s time to bring it back down to a workable temperature, but doing that the right way is important, too. The metal can either be cooled quickly—this is called quenching—or slowly in a furnace.
All the possible combinations of temperatures, soak times, and cooling methods result in a matrix of outcomes. And that’s even before you consider all the metals you may need treated. Further, some projects need the metals treated multiple times!
Annealing vs Normalizing
There are several types of heat treatment processes. These include tempering, hardening, case hardening, and, of course, annealing and normalizing. We will cover all these in due course, but this blog is about the differences between annealing and normalizing, so let’s look at them.
Annealing, normalizing, and all heat treatment processes are used to make metals more workable and more suited to the job we need them to do.
Annealing
Annealing is a heat treatment process most often used to increase ductility and reduce hardness. This is especially helpful as a follow-up treatment after the metal has been hardened to make the material less brittle and more formable for the project.
One key difference is the annealing process sees the cool in a temperature-controlled furnace, decreasing its temperature over time. This is a slower and therefore a more expensive cooling method.
Why is Metal Annealed?
As mentioned, the annealing process reduces hardness and increases ductility. Why would you want to do this?
- Hard, brittle materials are harder to bend or press without fracturing the material. Annealing makes the metal more formable.
- When metals are brittle, they can cause the tools inside a machining center to wear down quickly. Again, because annealing softens the metal, it helps extend the lifespan of the cutting tools when the metal needs to be cut.
- Annealing removes residual stresses. These stresses can lead to cracks, so it’s best to alleviate them early in the manufacturing process.
Which Metals can be Annealed?
Many types of steel and cast iron can be annealed. Other metals include aluminum, copper, and brass.
When Are Annealed Metals Used?
Common applications for annealed metals include:
- Work-hardened materials such as sheet metal that has undergone a stamping process or cold drawn bar stock.
- Metal wire that has been drawn from one size to a smaller size may also undergo an annealing process.
- Machining operations that create high amounts of heat or material displacement may also warrant an annealing process afterward.
- Welded components can create residual stresses. Annealing recreates the metal’s uniform physical properties.
Normalizing
Like annealing, normalizing also makes metals more ductile. The key difference between the two is annealing allows the material to cool slowly in a furnace, but normalizing sees the metal cooled in a room temperature environment.
A quicker cooling process means the material is slightly less ductile and slightly harder than if it had been annealed, but it is also generally less expensive than annealing.
Why is Metal Normalized?
Metals are usually normalized because another process has decreased ductility and increased hardness. This can happen either intentionally or unintentionally, so it can be good to know these processes can be undone if necessary.
The normalization process makes metal more formable, more machinable, and reduces the residual stresses in the material.
Many metals, including copper, can be both normalized and annealed.
Which Metals can be Normalized?
Many types of metals can be normalized. These include:
- Iron based alloys (tool steel, carbon stee, stainless steel, and cast iron)
- Nickel-based alloys
- Copper
- Brass
- Aluminum
When Are Metals Normalized?
Normalizing is used in many different industries for many different materials. Examples include:
- In the automotive industry, steel stampings may be normalized following the work hardening that occurs during their forming process.
- Nickel-based alloys in the nuclear industry may be normalized following the thermal microstructure alteration that occurs following welding.
- Carbon steel may be normalized after it is cold rolled to reduce brittleness.
When to Anneal and When to Normalize
Annealing will help make the material more ductile, while normalizing will make it harder. So, depending on what your specific project requires, you can choose which property is more important.
The processes can be used in combination, too. For example, if after the metal has been annealed to make it softer and more ductile, if you want to undo some of this ductility, you can do so through normalizing.
At Eagle Magnetic, we offer precision metalworking services. When you need annealing services, metal fabrication, CNC machining, CAD design, welding, powder coating, Eagle has the knowledge, experience, and expertise you need to create the right products for you and your project! Contact us today to get started.
