sparks and flames

Although raw spring materials go through many steps to bring them to a finished product — one of those being heat treatment — its up to the spring manufacturer to put the “final touches” on the material to make it as efficient as possible for the desired application. Heat treatment, the heating and cooling of metals to achieve some desired effect, is no different. While metals go through various heat treatment throughout production and refinement, spring engineers often complete the final treatments based on the specifications of the customer.

Different Types of Heat Treatment

Heat treatment is a kind of umbrella term when it comes to metal preparation for precision wire products and springs. There are three major types of heat treatment often used in spring manufacturing:

  1. Annealing
  2. Stress Relieving
  3. Aging

Annealing

The annealing of metals is used when you want to soften a metal and/or achieve some changes in its microstructure. The process involves heating a metal and holding at a specified temperature. After a set period of time, the metal is then cooled at a specific rate.

The three stages of annealing are recovery, recrystallization, and grain growth (we’ll avoid the thermodynamics of the process). The purpose of the process is to reduce the metal’s hardness, which allows it to become more malleable and easy to form.

Annealing is usually done by spring manufacturers if a metal that has a low tensile strength needs to be significantly worked.

Stress Relieving

Stress relieving of metals is similar to annealing in that metals are heated to a suitable temperature, then cooled a specified rate. The difference is that the metal is held at the high temperature longer, which reduces the residual stress, before cooling it very slowly to avoid the formation of new residual stress.

Metals that have gone through stress relieving have better machinability, they can be easily cut, and have a higher flatness standard. Spring manufacturers use this process to relieve the stresses, and return them to normal, that occur after the forming operation. This can even increase the strength of the material to a higher point before forming.

Aging

Aging, as it relates to heat treatment, allows for a change in the properties of certain metals and alloys. These changes occur at ambient and elevated temperatures after the heat treatment or cold working of metals. The change of the properties is (often) due to a phase change (precipitation), and is never involved in a change in chemical composition of the metal or alloy.

This process is simply used to increase the tensile and yield strengths of the metal to a higher level than the unaltered material.

Need Treated Wire for Springs?

At The Yost Superior Co., we can create spring from a variety of different treated wires. No request is large! Want to get a free quote on your spring order? Get in touch with our team and tell us what you need in your custom springs.