5160 Alloy Steel Springs

AISI 5160H Springs

At Coiling Tech, we work with various types of hot-rolled alloys including AISI 5160 when manufacturing springs. AISI 5160H springs are used in applications requiring high tensile strength and toughness. This material is commonly used in agricultural, automotive, mining, machinery, and light and heavy industrial use. The available material size range is 0.375” – 2.500”.

Custom AISI 5160 Springs

Coiling Technologies manufactures large custom springs to meet the specific requirements of our industrial customers. Our 5160 alloy steel 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 Alloy Steel Springs FAQs

What does the AISI 5160 designation mean?

In the AISI four digit system the leading 5 identifies a chromium alloy steel and the last two digits give nominal carbon in hundredths of a percent, so 5160 is a chromium steel at roughly 0.60 percent carbon. The published composition for the grade is 0.56 to 0.61 percent carbon with 0.75 to 1.00 percent manganese. The H suffix in 5160H denotes a hardenability grade, meaning the heat is supplied against a guaranteed hardenability band rather than chemistry limits alone. On thick suspension sections, where core hardness after quench has to be predictable, that distinction is worth calling out on the purchase order.

What makes 5160 the standard choice for leaf and heavy suspension springs?

High carbon supplies the elastic limit and chromium supplies hardenability and toughness, giving a material that takes repeated large deflections without cracking. That is precisely the loading a leaf spring or a heavy coil suspension spring sees. The published use for the alloy is automobile and heavy industrial production of medium and large cross section formed components requiring high tensile strength and toughness, with service in agricultural, automotive, mining, machinery, and light and heavy industrial equipment. Coiling Technologies names military suspension springs and large or heavy duty springs as specialties of the shop.

What size range is available in AISI 5160?

Minimum size in the specification table is 0.375 in (9.50 mm), and the available material size range is 0.375 in to 2.500 in. That floor sits far above the carbon wire grades and reflects what the alloy is for: bar and heavy wire sections where a pre-tempered wire cannot carry the load. Section size drives the entire process plan, since quench severity, tempering time, and achievable core hardness all shift with diameter. Supply the bar or wire diameter along with load and deflection requirements so the heat treat route can be set during quoting.

How hot can a 5160 spring run?

The specification table for this grade does not publish a maximum service temperature, so confirm the limit with CTI engineering for your part rather than assuming one. As a class, chromium and chromium vanadium low alloy spring steels are used up to about 450 degrees F (230 degrees C), the figure CTI publishes for its low alloy carbon grades, while plain carbon grades stop far lower. Above that range a spring loses load under sustained deflection instead of breaking, so relaxation rather than fracture is the failure mode you design against. State your operating temperature at RFQ.

What heat treatment does a 5160 spring require after forming?

5160 ships without a mill temper, so springs are formed and then austenitized, quenched, and tempered to the hardness that matches the load and fatigue requirement. Tempering temperature sets the trade between strength and toughness, and on a suspension part that single choice is the design decision. Decarburization during hot forming or austenitizing strips carbon from the surface layer and cuts fatigue life sharply, so furnace atmosphere control and surface inspection both matter. Coiling Technologies heat treats in house and can supply hardness results and load test data with the parts.

Should a 5160 suspension spring be shot peened?

For any dynamically loaded suspension spring, yes. Shot peening puts the bar or wire surface into residual compression, which delays fatigue crack initiation at the surface where cyclic tensile stress peaks. On leaf and coil suspension springs the fatigue life gain is large enough that peening is a standard production operation rather than an upgrade. Coverage and intensity should be specified, since both under peened and over peened surfaces underperform. CTI runs shot peen in house alongside coiling and heat treating, which keeps peening parameters controlled under the same quality system.

Does 5160 need corrosion protection?

Yes. 5160 has no meaningful corrosion resistance and will rust in service, which is a practical problem on suspension springs exposed to road salt, standing water, and abrasive debris. Coatings used on heavy springs include powder coating, which CTI applies in house, along with phosphate and oil or another metallic conversion coating. Electroplating a hardened 5160 spring introduces hydrogen embrittlement risk and requires prompt baking after plating, so many heavy spring programs avoid plating entirely. Where corrosion rather than load is the limiting factor, a stainless or nickel alloy spring is the better answer.

What should I include in an RFQ for a 5160 spring?

Send the bar or wire diameter, free length, outside or inside diameter, the load at working height or the rate you need, total deflection, whether the load is static or cycling, operating temperature, end configuration, and finish. Add any material standard the part must meet and any hardness cap your application imposes. If you have a physical sample instead of a drawing, that sample plus whatever dimensional or load data exists is enough to start. CTI's engineering team can develop a full design from performance requirements when no firm drawing exists yet.