Our Materials Make All The Difference
Along with one of the largest spring catalogs in the industry, Hardware Products also stocks the broadest array of materials to solve virtually any design challenge coming our way.
Whether you are searching for stainless steel springs or red metals springs, we have on hand well over 35 metals and alloys, including: Music Wire, Oil Tempered Wire, Stainless Steel, Chrome Silicon, Chrome Vanadium, Elgiloy® Hastelloy®, Inconel®, Monel®, Red Metals, Alloy Steel, Carbon Steel, 300 Series Stainless, 400 Series Stainless, Phosphor Bronze, Beryllium Copper and more, much more.
Tell us how you want your spring to perform, and we will find the ideal material to meet all your specifications. Ultimately, our precise materials mean a precision performance every time.
The Different Types of Spring Steel Used in Spring Manufacturing
Knowing How to Choose Your Raw Materials and Alloys for Steel Springs
Over the years, the spring industry has divided the common spring materials into different classifications. Some of these classifications have somewhat confusing or misleading names, but are used as jargon within the industry, nevertheless.
These classifications begin with raw materials, so we’ve broken them down and created a guide to help you understand the different classes of metal utilized in our operations. Think of this as a primer to define some basic terms as they relate to spring steel. If you were to look up these terms in the dictionary, you might find the definitions to be quite involved and off-putting, so rather than use them, we will offer Hardware Product’s simpler explanations of these spring steel terms. Read along below in chronological order or jump to the section that interests you most.
- Alloy Steel
- Stainless Steel
- High Nickel
- Red Metal
- Choosing an Alloy for Steel Spring Use
- How Hardware Products Company Can Help with Your Next Project
Metal is a class of element such as gold, silver, or copper. They are opaque, ductile, and have a luster to them. No springs are made from the primary elements—these are the first building blocks of steel—iron being the most common element in steel.
Steel consists of artificially produced forms of iron, which contain varying amounts of carbon. When looking at a certification for steel, the document will always indicate the amount of other materials contained within the steel. These percentages will not add up to 100% because the iron content is, by definition, the balance of the contents.
Almost all springs are made from a steel, although there are some plastic models that have recently been introduced to the market. There’s another way to look at steel in relation to steel spring manufacturing—think about steel as a classification, such as meat. We all know what meat is, but meat could mean lamb, beef, chicken, or pork. Alloys are the specifics, such as lamb or beef. Steel, is simply the classification they all belong to.
Alloys are comprised of two or more metals—or a metal with a non-metal content permanently mixed together. Alloys are similar to a recipe in a cookbook. At the top of the recipe are the contents, and at the bottom are the processing applications. Many of the steels have the same or similar chemical content, but are processed differently. This is similar to taking three eggs and frying one, hard-boiling another, and scrambling the third. Obviously the “raw material” is identical, but the end product is vastly different because of the means of processing. There are many important factors—conductivity, constant modulus, corrosive resistance, heat hardenability, magnetism, palatability, stress, and temperature— that you must consider when choosing which material (alloy) to use.
Within the spring industry, carbon is a term applied to “ordinary” steel. It’s comprised mostly of one of three types of steel—hard drawn, oil-tempered medium basic, or music wire. These are the least expensive and probably the most often used forms of spring steel.
This particular form of spring is the most common for two reasons. The most obvious reason is price. Just as important though, is the fact that most springs are used within the intensely oily environment of an industrial machine. The oil acts as a natural protectant for the springs, eliminating the need for corrosive resistance—a key product benefit found in other classifications.
Alloy steel is related to one of the confusing terms mentioned above. In order to make carbon steel stronger, the carbon steel is mixed with either chromium and vanadium or chromium and silicon. Consequently, the alloy names are oil-tempered chrome vanadium and oil-tempered chrome silicon. The two named products are actually carbon steel, but are usually classified as “alloy steel.”
Alloy steels are more expensive than plain carbon steel. They are typically used when there is not enough room for a carbon application—meaning some of the steel’s bulk has to be removed. Due to the slimming down of materials, the remaining steel has to be immensely sturdy and make up the difference in pound-for-pound strength.
Many different types of stainless steel are used in spring manufacturing. They are usually alloyed for one specific reason or another, but all of them have the typical stainless qualities of being corrosion resistant. The 300 series of stainless gets most of its hardness from being forced through reduction dies, and therefore, the molecules are “crunched together” to make them dense. The 400 series can be formed in a softer condition and then hardened later. Stainless is more expensive than carbon steel, and therefore, is only used when corrosive resistance is required in the manufacturing of stainless-steel springs.
High nickel is one of the components of stainless steel, and can also be added in different quantities for specific purposes. For example, some high-nickel alloys are used for high temperature, some are used for corrosion resistance in very caustic environments, and some are used for lack of magnetism. They are usually expensive, and generally used only when absolutely necessary.
Red metal is the only class of spring steel that does not have iron content. The common red metals are hard-drawn copper, beryllium copper, and phosphor bronze. They are typically used in electronic applications. They also are “weaker” than the alloys that contain iron. But in today’s world, there is a large market for springs made out of these products.
Choosing an Alloy for Steel Spring Use
Raw materials, such as the ones discussed above, are chosen primarily based on their properties and how they will impact the end use of a product. When selecting the alloy, think of it inversely: the end use dictates what alloys to use. Choosing an alloy for steel spring use is not nearly as automated a process as it is for raw materials—many engineers are not as knowledgeable of each alloy’s suitability to a spring application. As a result, many alloy inquiries involve providing solutions for which alloy should be used for a particular spring purpose.
When considering what (alloy) material to use, there are at least nine key properties that come into play.
- Constant modulus
- Corrosive resistant
- Heat hardenability
- Heating elements
- High stress
A spring serves multiple purposes—it not only acts as a spring, but also carries current. One such application is in the needle of an instrument. The reaction of the needle is both a function of the spring and of the amount of current running through the spring.
2. Constant Modulus
With some alloys, the spring will weaken if the temperature is too high or too low. If you’re planning on deploying a spring within a device that experiences wide temperature swings, a material known as a constant modulus, must be chosen.
3. Corrosive Resistant
Many springs are used in marine applications or very caustic atmospheres. In such cases, there are about seven different stainless steels that can be chosen. Some work in fresh water, but not salt water. Some work in salt water, but not more caustic environments. In such cases, a class of spring steels known as high nickel alloys can be employed.
4. Heat Hardenability
Some spring steels get their “hardness” from heat treating, while others get their hardness from being forced through a reduction die that compresses the steel. However, many of the alloys that get their hardness from reduction dies cannot be hardened through heat treatment. When making a spring or clip that has a very sharp bend on it, if you use pre-hardened steel, the steel will crack or break. In such an instance, you must use a steel that is in the “soft” or annealed condition, and then harden it after the spring or clip is formed.
5. Heating Elements
Some steels are themselves used for heating elements. In this instance, the alloy must resist electricity so that the electricity being forced through it heats up the wire to a red-hot condition. The alloy must be able to resist this heating and cooling without either melting or deforming in any way.
6. High Stress
When we were kids, we all made springs by twisting some copper wire around a pencil. But once we completed the spring, it was hard to get it off the pencil without deforming it! The spring’s ability to be deflected and then return to its original shape is governed by how much stress that particular alloy can handle. Sometimes a spring has to deflect a long way and then return to its original size. To be capable of this, the spring must be rated to resist high stress.
Springs are primarily used in sensitive instrument environments. When used in these applications, the spring cannot have any magnetism. Since many spring-tempered wires get their temper by being forced through reduction dies, they often pick up magnetism. For example, in its natural state, 302 stainless is totally non-magnetic. As a matter of fact, many engineers question us about the authenticity of our stainless springs because of this magnetism. The truth is that the material begins non-magnetic, but when forced through the die, it picks up magnetism. If a spring is to be totally non-magnetic, it must be made from an alloy specifically designed to be both spring tempered and non-magnetic.
When a spring is in a mildly corrosive environment such as an outside application, the spring has to be corrosive resistant, yet inexpensive. This calls for a spring that is electro-plated after formation. However, some materials are more porous than others, and when being electro-plated, hydrogen (the smallest atom), can get into the porous surface of the material and cause micro-cracks. These later become bigger cracks, which necessitates that a less porous material is chosen when plating.
Sometimes a spring has to be made of an alloy that can withstand high temperatures. For example, the springs on an oven door have to be able to withstand the heat from the oven without “relaxing.” In fact, many ovens function to extremely high temperatures and require springs that can maintain their properties for an extended period of time.
How Hardware Products Company Can Help with Your Next Project
For more than 100 years, Hardware Products has been manufacturing and delivering exceptional quality stock and custom springs around the globe. With the oldest stock catalog of springs in America, Hardware Products can supply in-stock or custom-made springs in most quantities in less than 24 hours. Just ask.
In spring manufacturing, we have the capacity to create virtually any shape and type of spring with a wide variety of spring steel—for an array of uses. Contact us to get in touch with one of our spring geeks today, and find out which steel will work best for your next spring project.
Our Complete List and Materials Definitions:
A Copper based alloy able of withstanding the high stresses necessary in springs. It is typically used where electrical conductivity is coupled with mechanical spring usage. Typically in applications such as switches, measuring instruments and the like.
Used where electrical conductivity is important but repeated spring cycling is not required. Lowest cost of the copper based alloys.
A copper base alloy that has good electrical conductivity but with only limited cycle life.
Also a low carbon steel where there is very little need for deflection or multiple cycling
A medium carbon steel again typically used for stamping type applications where the need for deflection is minimal – but the number of cycles is up from the low carbon steels
Available either in the soft or annealed condition where the spring (usually with sharp bends) is formed first and then hardened and tempered afterwards. Or it is available in a hardened and tempered condition and is used in spring formation where there are no sharp bends.
This is the highest carbon content available steel on a regularly attainable basis. As with 1075 carbon, it is available either in the annealed or spring tempered condition depending on the type of spring to be manufactured.
Carbon Valve wire is a carbon steel spring wire of a similar composition to Oil Tempered MB but is inspected every foot for seams and deformations because the applications are so critical that wire imperfections are not allowable.
Chromel A (R)
This is a wire that is used in heating elements. Spring companies do not normally work with this material when a spring is required. But some heating elements need wire formed in such a configuration that the spring manufacturing equipment is the best way to form it. In such cases the Chromel A is used.
This is virtually 100% copper and is usually softer than most spring manufacturing materials. It is used when the application is not so much that of a spring as it is is that spring manufacturing equipment is required to form the material in the appropriate configuration.
This is a cobalt-chromium-nickel-iron alloy developed by and trademarked by the Elgiloy Corporation. It is a nonmagnetic alloy suitable for below freezing and or elevated temperature environments. It is also suitable for caustic environments due to its corrosive resistance.
Hard Drawn wire is really called Hard Drawn Medium Basic. It is the least expensive of the Medium Basic Wires and is used in the manufacture of springs where a higher tolerance and/or a lower stress are required.
Hastelloy is a nickel-molybdenum-iron alloy developed to be a highly corrosive resistant alloy and can be used where spring properties are needed in a highly caustic environment.
Hastelloy C (R)
Hastelloy C is also a nickel-based alloy developed to be highly corrosive resistant. It can resist corrosion from caustic gasses, strong oxidizing compounds and sulfuric acid. It has just slightly lower tensile strength than hastelloy.
Inconel 600 (R)
Inconel 600 is a nonmagnetic nickel-chromium alloy which is cold drawn to high tensile strength condition for its spring properties. It can be used in moderate heat, but cannot be heat-treated for additional strength
Inconel 625 (R)
Inconel 625 is a highly specialized alloy used for very specific purposes and is quite similar to Inconel 600
Inconel 718 (R)
Inconel 718 is a non-magnetic nickel-chromium alloy which is a precipitation hardenable alloy that can be cold drawn to high tensile strengths and then heat-treated for even greater strength
Inconel X-750 is a non-magnetic nickel chromium alloy which has small amounts of other elements added to make it precipitation hardenable. It can operate in a high temperature environment with out relaxation
MP35N is a high nickel alloy that is used for specific purposes where corrosive resistance is required. It is less common than other high nickel alloys and is therefore more expensive and used sparingly.
Monel 400 (R)
A nearly nonmagnetic nickel base alloy made of nickel and copper. It has a fairly high tensile strength for good spring properties and is reasonably corrosive resistant.
Monel K-500 (R)
Like Monel 400 it is a nickel and copper base alloy but it can be formed in a softer condition for applications with more bending required and then hardened after forming. It too has a good corrosive resistance.
Music Wire is high carbon steel that is cold worked for its tensile strength. It is the most common of all spring steels in smaller sizes where superior quality is required. Because it is cold formed, its surface is better conditioned to receive electro-plating for corrosive situations than other high carbon steels.
This is a nickel-iron-chromium-titanium alloy that is a popular constant modulus alloy. It can be formed first and then precipitation hardened for uniformity.
Oil Tempered MB
Oil Tempered MB (for Medium Basic) is one of the most widely used carbon steels for the manufacture of larger wire size springs. It is available in a wide variety of sizes but because it is more porous than music wire it is not recommended to be electro-plated.
Oil Tempered Chrome Silicon
Chrome Silicon is considered alloy steel. It has small amounts of chromium and silicon added to it which makes it the most readily available carbon steel capable of achieving very high stresses. It must be heat treated within two hours of any forming and is therefore only used where the high stress requirement is a necessity.
Oil Tempered Chrome Vanadium
Chrome Vanadium is considered alloy steel. It has small amounts of both chromium and vanadium added to it which allows it to withstand higher operating stresses than Oil Tempered Medium Basic although not quite as high as chrome silicon. It is easier to use than chrome silicon and is therefore more popular where stress limits are within stated parameters.
Most extensively used of the copper base spring alloys. It is good for electrical conductivity and has the ability to withstand repeated cycling.
Stainless Steel Type 17-7
Type 17-7 Stainless is a precipitation hardenable stainless steel capable of handling higher stress applications than other grades of stainless steel. It is subject to cracking if it is deflected down to solid height and so care must be taken to make sure that the spring does not go down to solid.
Stainless Steel Type 301
Stainless Steel Type 301 is the most common of the 300 series stainlesses in strip. It is able to withstand the high stresses necessary in spring applications in a flat spring environment.
Stainless Steel Type 302
Type 302 is the most common of the round spring wire stainlesses. It is capable of moderate corrosion resistance such as from regular water but can corrode over time and is not recommended for salt-water applications.
Stainless Steel Type 308
Type 308 is commonly used in welding applications and therefore welding rings are frequently formed of 308 and then put into the application where a weld is needed.
Stainless Steel Type 316
Type 316 is more resistant to corrosion than type 302 stainless especially in the presence of different types of salts. It has design parameters with approximately 15 percent lower design stresses than type 302 stainless.
Stainless Steel Type 410
This type of stainless is used where a 400 series stainless is desired and where stress limits do not have to be as high. It typically has stress design parameters 15% lower than 302 stainless.
Stainless Steel Type 420
This is the type of stainless generally used in large diameters. It is frequently formed in the annealed condition and then hardened after forming.