Stainless steel’s tolerance to high temperatures and moist environment draws customers to this type of material. While it is more expensive and weaker than carbon steels, it may be worth it. Unlike carbon steels, stainless steel can withstand temperatures from 550ᴼF to 650ᴼF depending on the type. In addition, stainless is more resilient to corrosion such as rust. Passivating stainless steel springs will further enhance its corrosion resistance capabilities.
It is important to note spring tempered stainless steel is slightly magnetic, unlike raw stainless. To make the different wire diameters, stainless steel is drawn at room temperature. This process is called cold drawing. The cold drawn process changes the properties of stainless steel; hardening it and making it magnetic. The more cold work needed (i.e. the smaller the wire diameter), the harder and the more magnetic the stainless will become. This is why using a magnet to determine the material of a spring is misleading.
For more information on the properties of stainless steel, check out our glossary at the link below.
Music wire is the most popular material used for coiled springs and is recommended by most spring designers. It has a high and consistent tensile strength, an ability to take severe bends, and a long useful life. In addition, its cost is very similar to the lower quality carbon steels, especially when the wire diameter is small and the quantity needed is low.
However, there are some issues with using music wire.
- It is not corrosion resistant. Appling a protective coating, like zinc plating, can help slow corrosion. However, if the spring is exposed to harsh elements, stainless steel may be best.
- It cannot withstand high temperatures above 250ᴼF. For high temperature requirements, switch to 302 stainless steel.
- It loses its high tensile strength as the wire diameter increase. Generally spring designers will suggest oil temper at these large wire diameters.
- Is not very cost effective in low stress and large quantity application. For large production needs and low stress applications, hard drawn carbon steel is the way to go.
For more information about the properties of music wire check out our glossary.