Alloy Steel 5160 Springs

Alloy Steel 5160H, also known as AISI 5160H or SAE 5160, it is a high carbon chromium spring steel. 5160 is very common alloy and has been used in spring manufacturing for more than 100 years. 5160H is typically utilized in spring applications where larger material diameters are required. Its most common use is in material diameters greater than 0.625” (15.88 mm), although the material can be obtained in sizes as small as 0.375” (9.5 mm).

The material is usually delivered in bar form and comes in the as-rolled condition. However, the material is also available from the mill in coil form as well, so long continuous lengths are available to create spring free lengths up to 80”. Coiling Technologies stocks 40 ft, 45 ft bar and 4000 lbs. coils of 5160H. For sizes larger than 1.25” diameter the alloy may be enhanced with Boron so that the material hardness can be maintained when utilizing large diameters up and beyond 2.5” in diameter.

Springs manufactured from AISI 5160H steel provide a high tensile strength, toughness, and good fatigue resistance. This allows the spring to be designed to a lower mass because of the higher tensile properties over other high carbon non-alloyed steels. 5160H will return to their original shape post-deformation under high dynamic conditions which makes the material ideal for large spring applications for a myriad of industries.

Most manufacturers hot coil 5160H material however, Coiling Technologies has devised methods to cold form this alloy with material diameters up to 2.50”. This cold forming technology can produce springs that have a very uniform hardness. This certainly comes into play when producing very large springs with long bar lengths. When quenching large springs, the temperature is very uniform when they come out of the austenitizing furnace. The springs are uniformly quenched to ensure consistent hardness throughout the spring. The springs are then tempered in a batch oven to ensure the final hardness corresponds to the desired tensile properties.

Material Composition

Chromium is the major alloying element in 5160 steel. AISI 5160H steel also includes other key elements:

  • Manganese
  • Phosphorus
  • Silicon
  • Sulfur

AISI 5160 steel also has a carbon concentration which is 0.60% carbon, making it a medium to high carbon steel.

AISI 5160 is a hot rolled steel, produced by processing material at temperatures above the recrystallization temperature of the material. Hot roll is for applications where the finished surface quality is not as critical. However, the material can be obtained with a bright finish that is turned and polished for improving the surface condition for extending the fatigue properties. The material is very flexible as it can be heat treated to various hardness to meet various operating environments. 5160H can be heat treated to a hardness range as high as 51 HRc and still meet the ductility requirements for a dynamic spring application. Although, in most instance the material hardness for most spring applications falls into the 40 – 46 HRc range. Therefore, it can be utilized in various ambient conditions from -50F to 250 F (-58C to 170 C).

The chromium that is present in AISI 5160H is not at high enough levels to reduce its susceptibility corrosion, therefore it is important to coat the spring with a rust preventative or a protective coating to ensure the material is not exposed directly to the elements. Coiling Technologies offers various coating and plating solutions to ensure springs produced from 5160H do not corrode when used in their intended application. Powder coating is one of the most common forms of protection from the environment. It can also be plated; however, it is important to bake the material properly post electro plating to eliminate the risk of hydrogen embrittlement.

Applications of AISI 5160 Carbon Steel

Because of its availability and cost-effectiveness, AISI 5160H steel is utilized for a very large variety of applications. AISI 5160H steel is most commonly used for springs in railroad and automotive suspensions because of its strength and ductility and fatigue properties.

Industries using springs manufactured from AISI 5160 steel include:

Coiling Technologies Inc. uses AISI 5160 steel to make different types of springs used in a wide range of industrial applications. The high tensile strength of AISI 5160 is often implemented in applications with smaller cross-sections under significant stress.

Types of Alloy Steel 5160 Springs

Customized Design & Manufacture

Coiling Technologies, Inc. is driven to provide exceptional service in the spring industry. We accomplish this every day with every customer and client with our highly skilled engineers, well-experienced staff, and the best practices we apply to our manufacturing products and services.

We offer our customers comprehensive services beginning from requirement gathering and analysis, assistance in design, and manufacture springs using AISI 5160 steel that meets your requirements for quality and cost.

For springs manufactured using AISI 5160 steel, Coiling Technologies, Inc. can readily procure the steel you need, efficiently process the steel, and expertly engineer high-quality, high-performance springs that meet your exact dimensions and application requirements.  

We can deliver springs made from AISI 5160 steel in a wide range of sizes. Springs made of 5160 steel are available from 3/8 inch to 2 ½ inches in diameter.

Our customization is unbeatable, and with our springs’ high-performance and quality, you can count on us to deliver exactly what you need every time.

Your Customized 5160 Carbon Steel Spring Partner

Coiling Technologies Inc. has the technical expertise, industry experience, and manufacturing capability to meet your suspension spring needs.

Coiling Technologies manufactures large custom springs to meet the specific requirements of our industrial customers. Our springs can be custom manufactured using a wide variety of alloys, including AISI 5160. The team is available to help you create the right product for your application.

Our custom springs are manufactured and delivered with the highest quality of manufacturing and service. Contact us today!

 

 

5160 Steel Springs FAQs

What is AISI 5160 spring steel and what makes it a preferred material for heavy-duty springs?

AISI 5160 is a chromium-alloyed spring steel containing approximately 0.56%–0.64% carbon and 0.70%–0.90% chromium. The chromium addition serves two critical functions: it improves hardenability—allowing larger cross-sections to harden uniformly throughout—and provides significantly better toughness and impact resistance at equivalent hardness levels compared to plain carbon spring steels. This combination of through-hardening capability and superior toughness has made 5160 the standard material for heavy-duty leaf springs and large industrial coil springs for over a century.

What size range of 5160 springs can Coiling Technologies produce?

Coiling Technologies stocks AISI 5160H in 40-foot and 45-foot bar lengths as well as 4,000-pound coils, and manufactures springs with wire diameters from 0.375 inches up to 2.50 inches and free lengths up to 80 inches. For diameters above approximately 1.25 inches, Coiling Technologies uses a boron-enhanced version of the alloy to maintain uniform hardness at those larger cross-sections, where standard 5160H may not harden fully through the section without the boron addition.

Does Coiling Technologies hot-form or cold-form 5160 steel springs?

While most spring manufacturers hot-coil 5160H at larger diameters, Coiling Technologies has developed the capability to cold-form this alloy in wire diameters up to 2.50 inches. Cold forming produces a more uniform hardness profile throughout the spring cross-section compared to hot coiling followed by quench-and-temper, which matters most when processing very large springs with long bar lengths where thermal mass during quenching can create hardness gradients. This cold-forming capability in large-diameter 5160H is a manufacturing differentiator for programs requiring consistent through-hardness at heavy section sizes.

What role does chromium play in AISI 5160's performance compared to plain carbon spring steels?

Chromium in 5160 improves hardenability—the depth to which the steel can be hardened by heat treatment—enabling heavier cross-sections to achieve uniform hardness throughout rather than just at the surface. Chromium also improves toughness at a given hardness level compared to plain carbon steels, meaning 5160 absorbs more impact energy before fracturing. This toughness advantage is why 5160 is the preferred material for springs that must absorb dynamic shock loads in addition to cyclic fatigue loading. For applications where a plain carbon steel like 1095 would be adequate in strength but insufficient in toughness, 5160 is the correct upgrade.

What hardness range can 5160 steel springs be heat treated to?

AISI 5160H can be hardened as high as 51 HRC while still meeting ductility requirements for dynamic spring applications, though most production applications target 40–46 HRC for the best balance of strength and toughness. The specific hardness target depends on wire diameter, spring geometry, operating load, and the severity of any impact loading the spring will experience in service. For extreme shock-load applications, lower hardness targets (40–44 HRC) with improved toughness are often appropriate even if they reduce maximum spring rate.

Do 5160 steel springs need a protective coating for outdoor or exposed service?

Yes. The chromium content in 5160H is not sufficient to provide meaningful corrosion resistance—far below the approximately 11–12% chromium minimum required for stainless behavior. Protective coating is important for any 5160 springs exposed to moisture or outdoor environments. Common treatments include powder coating (widely used for automotive and commercial vehicle leaf springs, providing excellent coverage and durability), epoxy or polyurethane paint systems, zinc-rich primers followed by topcoats, and phosphate treatments used in some military applications.

What industries most commonly use 5160 steel springs?

5160 steel springs are common in: heavy truck and commercial vehicle leaf spring systems, agricultural and construction equipment suspension (tractors, combines, earthmovers), military vehicle springs (5160's toughness and through-hardening capability make it well qualified for the shock loads encountered in off-highway military vehicles), railroad car springs, mining and quarrying equipment, oil and gas field equipment subject to heavy dynamic loading, and general industrial applications where the spring must carry heavy loads and absorb impact regularly without fatigue failure.