Annealing Steel

The Benefits of Annealing

annealing steel

You may have heard about the amazing durability of the katana sword used by samurai for many years in Japan. Such a blade is able to keep its sharpness and shape even when put through intense stress and a long period of constant use. There are many secrets to why these blades have been regarded by many experts as having superior durability, and one of these is a process known as annealing. Annealing steel or any other metal involves heating it to a specific temperature and allowing it to cool at a specified rate. Doing so removes impurities in the grain, increasing the metal’s ductility and reducing its hardness.

Today, the process of annealing steel and annealing metals is used in many industrial applications where the metal must be at the highest quality. The process has been enhanced with modern machinery to the degree that now the legendary durability of the samurai katana can be achieved in many industrial metals.

A Summary of the Annealing Process

A piece of metal is composed of a lattice of crystal structures known as grains, and sometimes these grains align in such a way that they cause additional stress to the metal piece as a whole. In the first stage of annealing steel or other metals, known as recovery, the metal is heated to a point at which these internal stresses can dissipate. Further heating the metal to just below its melting point allows new grains to form that don’t have the preexisting stresses of the old grains. This formation of new grains is called recrystallization. In order to control the growth of these new grains, the metal is allowed to cool at a specific rate, in what we call the grain growth stage.

The completion of this entire process results in metal with superior ductility and reduced hardness. Why is it sometimes better to have metal with reduced hardness? If a piece of metal is too hard, that makes it brittle. The most durable metals have high ductility, which means that they can bend and absorb impacts without breaking. Annealing metals is a way to achieve this much-desired balance between hardness and ductility.

Industrial Uses of Annealed Metal

annealing metals

Many of the industrial processes that are common today require or are enhanced by using annealed steel and annealed metals. For instance, to reduce the residual stresses of welding, often the welded structure is treated with an annealing process. Annealing can also strengthen metal that has been super-heated through high-intensity machining. When a metal wire is drawn thinner, it can cause stresses in the grains, and as such, new metal wires will often be annealed. Additionally, the process of making sheet metal can create a piece with too much hardness, so sheets are often annealed to restore their durability.

How Exactly Does Annealing Change the Behavior of Metals?

So what are the actual results of annealing metal to increase its ductility and lower its hardness? A piece of metal can crack or even break if it is left with residual stresses, and since annealing removes these residual stresses, it can help metal keep its shape. Annealing is also helpful to improve the lifespan of machining tools. Working a brittle piece of metal can cause additional wear on tools, whereas a highly ductile piece of metal will minimize the damage to the tools caused by constant use. The last benefit is something you may have already inferred: Annealing metals allows them to be more easily bent and formed into your desired shapes.

Your Heat Treatment Specialists

If you think that your operation would benefit if you took your metals through the annealing process, talk to our experts here at Specialty Steel Treating and we will make our recommendation. Our state of the art heat treating process will provide amazing results. Call us today at 586-571-0331.

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