Metal Springs can be found in almost every industry in the world. They can be found in materials used by the food industry, medical sector, piping, oil and gas, aerospace and beyond. Springs should have properties like, high strength, high elasticity, corrosion resistance, formability, fatigue strength and, in some cases, magnetic permeability and electrical conductivity. This long list of characteristics makes Stainless Steel the natural choice when choosing materials for the manufacturing of springs. Stainless Steel resists rust, it is a durable material and it has high yield strength.
Commonly used for springs, stainless steel is ideal for settings where higher corrosion or heat resistance is a necessity. This steel alloy has a minimum of 10.5% chromium content and a maximum of 1.2% carbon content. Stainless steel comes in several different grades, each with its own properties, as well as types: austenitic, martensitic and precipitation hardening.
Austenitic stainless steels are hardened by cold work and are useful for applications where resistance to corrosion is required; martensitic stainless steels also have good resistance to corrosion and are strongly magnetic, although they have poor electrical conductivity; and precipitation hardening stainless steels have high tensile strength and great resistance to fatigue, though they can crack due to stress.
At NKS, we provide materials for spring manufacturers across the country. In order to best advise our customers as to the grade and finish of the metal they are sourcing, we have to understand the different kinds of springs being manufactured, and the intended application for those springs.
Types of Springs
Torsion Springs – These are tightly coiled springs whose force is created by torque or twisting.
Extension Springs – These springs are coiled similarly to Torsion Springs. When these springs are pulled, or extended, they exert the highest levels of mechanical energy.
Compression Springs – These are the opposite of Extension Springs. When these springs are fully extended they are at rest, but when they are compressed they exert the highest amount of stored energy.
Flat Spring - Flat springs are flat strips of material that, when deflected by an external force, store and release energy.
NKS provides materials for all types of springs and can help advise you on which material would best suit your intended application.
As you may know, Stainless Steel comes in a diverse range of grades and finishes. The grade of the metal is determined by its chemical, physical and mechanical performance. So, which Stainless Steel grades are often sourced in the manufacturing of springs?
Type 301 Stainless Steel is an austenitic chromium-nickel Stainless Steel that provides high strength and good ductility when cold worked. The chromium and nickel contents are lowered to increase the cold work-hardening rate. This generates higher tensile strengths when cold rolled with a lower loss of ductility than with Types 302 and 304. The grade is essentially non-magnetic when annealed. When cold worked, it becomes slightly more magnetic than other standard austenitic Stainless Steels.
The typical applications for 301 Stainless Steel include structural parts, trailer bodies, diaphragms, utensils, architectural and automotive trim, wheel covers, roofing products, and kitchen utensils. For example, a commonly used household products like a whisk, tongs, or a hose clamp utilize steel springs, many of which are manufactured from 301 Stainless Steel.
Type 302 Stainless Steel is an austenitic chromium-nickel Stainless Steel, non-hardenable by thermal treatments. It may be cold worked to high tensile strengths with slightly lower ductility than Type 301. Its corrosion resistance is superior to that of Type 301. Type 302 is essentially nonmagnetic in the annealed condition and becomes slightly magnetic when cold worked.
The typical use for 302 Stainless Steel is within automotive and architectural trim, kitchen and restaurant equipment and utensils, and dairy and food processing equipment. For example the dairy industry uses air actuators to move products through a system of ducts in safe and sanitary ways. The air actuator uses a series of springs to open and close ducts.
Type 304 Stainless Steel is the most widely used of the austenitic (chromium/nickel) Stainless Steels. In the annealed condition it is essentially non-magnetic and becomes slightly magnetic with the application of cold work. Type 304L Stainless Steel is preferred in welding applications to exclude the formation of chromium carbides during cooling in the heat affected region of the weld. These alloys represent an excellent combination of corrosion resistance and fabricability.
The typical applications of 304 and 304L Stainless Steel are chemical equipment and piping, heat exchanger components, dairy and food handling equipment and utensils, cryogenic vessels and components, and architectural and structural applications exposed to non-marine atmospheres. In piping, Stainless Steel Springs are used to support the pipe during vibration or other atmospheric hinderances. The piping must be supported in a correspondingly elastic manner so to compensate slight vertical displacements in the piping.
Type 316 Stainless Steel is an austenitic chromium nickel Stainless Steel containing molybdenum. This addition increases general corrosion resistance, improves resistance to pitting from chloride ion solutions, and provides increased strength at elevated temperatures. Properties are similar to those of Type 304 except that this alloy is somewhat stronger at elevated temperatures. Corrosion resistance is improved, particularly against sulfuric, hydrochloric, acetic, formic and tartaric acids; acid sulfates and alkaline chlorides. Type 316L Stainless Steel is an extra-low carbon version of Type 316 that minimizes harmful carbide precipitation in the heat affected zone during welding.
316 and 316L Stainless Steel are often used in exhaust manifolds, furnace parts, heat exchangers, pharmaceutical and photographic equipment, valve and pump trim, chemical equipment, digesters, tanks, evaporators, pulp, paper and textile processing equipment, and parts exposed to marine atmospheres and tubing. In the chemical and pharmaceutical industries, catalyst retaining springs are used to manage the activity of a chemical catalyst in a test-tube. Additionally, Stainless Steel valve springs are used for offshore oil pumps.
These are just some of many applications for Stainless Steel Springs. As a major Stainless Steel distributor, NKS has a large and diversified inventory of stainless coil in a wide range of grades, gauges, tempers and finishes, allowing us to provide a broad range of products to our customers. Since NKS purchases its stainless steel from both domestic and foreign mill sources, we can identify the best mill source for the customers’ application, depending on the industry and end-use.
Contact NKS to Learn More
To find out more about our diverse product-line please visit www.nks.com. If you already know what you’re looking for, you can request a quote from us by email firstname.lastname@example.org or by visiting https://nks.com/locations/request-a-quote/. And finally, if you would like to be consulted on what grade and finish of metal would work best for your intended application, we can advise you. Please contact email@example.com and our knowledgeable staff will find the material that’s right for you.