Materials What our disc springs are made of, and where it comes from
This page briefly introduces the materials our products are made from, and the procurement policies we have in place.
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Conflict Minerals
The four most commonly mined conflict minerals (known as 3TGs, from their initials) are cassiterite (for tin), wolframite (for tungsten), coltan (for tantalum) and gold ore, when they are extracted in a conflict zone and sold to perpetuate the fighting. The Democratic Republic of the Congo (DRC) and its neighbouring countries in sub-Saharan Africa are the key focus of UN efforts to control conflict minerals.
Reliable Pressings policy
As South Africans, we are probably more aware than most of the impact this source of funding has in prolonging conflict, and of the suffering and destruction that help trap Africa in a seemingly never-ending cycle of poverty.
The USA was the first to pass legislation: the Dodd-Frank Act, which contains the Conflict Minerals Rule. Should we manufacture, or contract to manufacture, any products that contain conflict minerals, we will conduct a Reasonable Country of Origin Inquiry (RCOI) into the source and chain of custody of those minerals.
DFARS
DFARS is US preferential procurement legislation “…to provide a preferential treatment for domestic sources of non-manufactured articles, manufactured goods, and construction materials…”. This protectionist policy is a response to threats of espionage, sabotage and terrorism.
Among many other things, it states that any specialty metal must have been melted in a qualifying country. These include Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Egypt, Estonia, Finland, France, Germany, Greece, Israel, Italy, Japan, Latvia, Luxembourg, the Netherlands, Norway, Poland, Portugal, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom of Great Britain and Northern Ireland, and the United States.
The official DFARS website contains everything you may wish to research.
The Materials We Use
Default materials
65Mn: a quality spring steel, which we use exclusively for our Conical Wedge Lock Umlung® safety washers and DIN 6796 Belleville load washers for static bolted connections.
C75S / SAE 1075 (1.1248): a carbon spring steel to DIN EN 10132-4, used as cold-rolled strip for Group 1 disc springs to DIN EN 16983 (t < 1.25 mm) and for our “K” series disc springs.
51CrV4 / SAE 6150 (1.8159): a chromium-vanadium alloy spring steel, used in rolled condition (to DIN EN 10132-4 or DIN EN 10089) for disc springs from 1.25 mm to 6 mm thick. For discs thicker than 6 mm it is normally processed in forged form.
Corrosion-resistant materials
X10CrNi18-8 (1.4310): a chromium-nickel stainless steel to DIN EN 10151, the most commonly used material for stainless disc springs up to t = 3.0 mm. Unfortunately, cold forming makes it partly magnetic.
X7CrNiAl17-7 (1.4568): a precipitation-hardening stainless spring steel to DIN EN 10151, processed in the cold-worked condition up to about 2.5 mm. Cold forming makes this material magnetic.
X5CrNiMo17-12-2 (1.4401): a little lower in strength than the two above, but with higher corrosion resistance and lower magnetism. Small quantities are hard to procure, so it is rarely used.
High-temperature materials
X22CrMoV12-1 (1.4923): a chromium-molybdenum-vanadium steel to DIN EN 10269 that can be quenched and tempered. It has proved very good for heat-resistant disc springs.
X39CrMo17-1 (1.4122): a chromium-molybdenum stainless steel to DIN EN 10088-2 that can be quenched and tempered. It has also proved very good for heat-resistant disc springs.
Heat-resistant special alloys with very good corrosion resistance
These grades are often used in extreme operating conditions, where creep under load can cause a loss of installed height and force. Creep depends on temperature, time and stress. A disc spring can be used at higher temperatures if, for example, the load is low or the exposure time is short, so no single maximum working temperature can be stated. The values in our material overview are a guide only.
NiCr15Fe7TiAl, INCONEL X-750 (2.4669) and NiCr19NbMo, INCONEL 718 (2.4668): nickel-chromium alloys that are virtually cobalt-free, which is why they are often used in nuclear reactor technology.
Non-magnetic and corrosion-resistant materials
CuSn8 (2.1030): tin bronze to DIN EN 1654, an alloy of copper and tin that gets its spring properties from cold forming. Please bear in mind that its strength, and so the spring forces, are considerably lower than with the standard material.
CuBe2 (2.1247): copper-beryllium to DIN EN 1654, an excellent spring material that is suitable for extremely low temperatures, down to near absolute zero. These copper alloys are completely non-magnetic, have very good electrical conductivity, and are highly corrosion resistant against many media.
A note on spring calculations
Published disc spring data and our product lists use E = 206 000 N/mm2 and μ = 0.3, which apply to spring steel. Stainless, heat-resistant and non-ferrous materials have a lower tensile strength and a different Young’s modulus, so their springs usually cannot be designed with the same free height and give lower forces. We recalculate every design in the actual material.
Spring Steel Grade Guide
Common spring steels, their equivalent names and typical uses. On a phone, swipe the table sideways.
| Category | Popular names | Application | Elements, % of total | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Cr | Mo | V | Ni | |||
| Unalloyed carbon steel | C55S, 1.1204, CS50, CK55, SAE 1055 | Spring steel with low hardenability for lightweight springs, washers and spring elements, small tool blades and small equipment. Carbon about 0.55% for hardening and tempering, patenting or cold forming. | 0.52–0.60 | 0.15–0.35 | 0.60–0.90 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C60S, CK60, 1.1211, SAE 1060 | A spring steel with reduced sulphur and phosphorus, used for wear-resistant, heavy-duty parts such as axles, rollers, spindles, spring rings and flat springs up to 6 mm thick. A hardening and tempering steel that is easy to machine when annealed. | 0.57–0.65 | 0.15–0.35 | 0.60–0.90 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C67S, 1.1231, XC68, AISI 1065 | Not weldable, prone to decarburisation and oxidation during heat treatment, and not resistant to atmospheric corrosion. Low hardenability, for lightly loaded springs, oil hardened or surface hardened, up to about 10 mm. Used for valve springs, coupling springs, shock absorbers, flat springs and adjustable washers, and as a tool steel for hammers, punches, rakes and chisels. | 0.65–0.73 | 0.15–0.35 | 0.60–0.90 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C75S, 1.1248, AISI 1075, XC75 | Low hardenability, for lightweight oil-hardened springs, with good abrasion resistance and high strength. Used for lightly loaded springs, spring parts, clock springs and stone-cutting saw bands. As a constructional steel, it is used for medium-weight machine parts such as bolts, bucket links, rolls, agricultural machinery parts, press plates and ball mill parts. Not weldable; resistant to temper embrittlement. Our standard material for Group 1 disc springs. | 0.70–0.80 | 0.15–0.35 | 0.60–0.90 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C85S, 1.1269, XC85, AISI 1086 | Low hardenability, oil hardened, for lightly loaded, intermittently working springs and spring elements; not susceptible to temper brittleness. High hardness and abrasion resistance while keeping high strength. Used for flat and spiral springs, machine parts and saws of all kinds, ball mills, press plates, stone saws, steel rope wire and briquetting press parts. Not weldable, and not corrosion resistant. | 0.80–0.90 | 0.15–0.35 | 0.40–0.70 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C90S, 1.1217 | Oil hardened, for small, intermittently working springs, supplied as spring strip. High abrasion resistance and strength. Besides springs, used for wood and stone saws, knives and machine shears, spring washers and cutting tools. After heat treatment it has a tempered martensite structure. | 0.85–0.95 | 0.15–0.35 | 0.40–0.70 | ≤ 0.025 | ≤ 0.025 | ≤ 0.40 | ≤ 0.10 | – | ≤ 0.40 |
| Unalloyed carbon steel | C100S, 1.1274, AISI 1095 | Used for spring washers, spring elements, feeler gauges and other loaded parts that need high elasticity and tensile strength. Available as strip and thin cold-rolled sheet for springs and leaf springs with small cross-sections. Low hardenability, abrasion resistant, tends to decarburise and oxidise during heat treatment, and is not resistant to atmospheric corrosion. | |||||||||
| Unalloyed carbon steel | C125S, 1.1224, XC125 | Used for leaf springs and springs with small cross-sections. Low hardenability and a higher carbon content than C90S, C85S, C75S and C67S. For spring elements that need high elasticity and hardness. Not corrosion resistant; poor heat treatment reduces fatigue strength. | |||||||||
| Manganese spring steel | 65Mn, 65G, 66Mn4, 1.1240, 1.1260 | For leaf springs and springs with low hardenability that need better abrasion resistance: rings, valve springs, flat and coil springs and spring washers with small cross-sections and loads. Oil hardening, not sensitive to temper brittleness. Not resistant to corrosive environments. | |||||||||
| Silicon spring steel | 56Si7, 55Si7, 1.5025, 1.5026 | One of the most popular, simplest and longest-used grades for spring elements and springs in the automotive and railway industries. High strength, resilience, low ductility, susceptible to decarburisation, suited to medium loads, low hardenability and difficult to weld. 55S2, 50S2 and 40S2 (EN/DIN 56Si7, 50Si7, 46Si7) have similar alloy contents, including the silicon responsible for the steel’s resilience; the grades differ in carbon, which sets the hardness after heat treatment. | |||||||||
| Silicon-chromium spring steel | 54SiCr6 (1.7102), 60SiCr8 (1.7108), 60MnSiCr4 (1.2826) | High hardenability, strength and ductility for heavy-duty springs and spring elements subject to impact. Used in railway rolling stock, for example buffer rings on wagons. Can operate at up to 300 °C. Also used for valve springs, torsion shafts and spring rings. Not weldable, and not corrosion resistant, including to the atmosphere. | |||||||||
| Silicon-chromium-nickel spring steel | 52SiCrNi5, 1.7117, 52SCN5 | Used for statically loaded, small and medium-size springs. A better alternative to 51CrV4 (1.8159) for these. | |||||||||
| Silicon-chromium-molybdenum spring steel (approved for aerospace) | 46SiCrMo6, 1.8062, 45SCD6 (EN 10089, AFNOR NF A35-571) | A silicon spring steel with chromium and molybdenum added, resistant to torsion, deformation, load, impact and abrasion. Mainly used in the automotive and machine industries for springs and spring elements such as stabilisers, rods and leaf springs. | |||||||||
| Chromium-vanadium spring steel | 51CrV4 (1.8159), SAE/AISI 6150, 58CrV4 (1.8161), 59CrV4 (1.2242) | Structural alloy used in engineering for heavy-duty spring components and oil-hardened springs. Unlike other carbon and alloy grades it combines high hardness, low sensitivity to tempering, resistance to variable and heavy loads, and the ability to operate at up to about 300 °C (DIN EN 16983 lists 51CrV4 disc springs for up to 150 °C without significant relaxation). When surface hardened, the core keeps excellent strength with enough surface hardness. Our standard material for Group 2 and 3 disc springs. | 0.47–0.55 | 0.15–0.35 | 0.70–1.10 | ≤ 0.035 | ≤ 0.035 | 0.90–1.20 | – | 0.10–0.25 | – |
| Chromium-molybdenum-vanadium spring steel | 52CrMoV4 (1.7701), 51CDV4, 51CrMoV4 | Oil-quenching spring steel: hard, ductile and hardenable. Used for all types of automotive springs with high strength requirements, including shock absorber springs, sealing rings and valve springs. Its strength and hardenability come not only from chromium and vanadium, as in 51CrV4 (AISI 6150), but also from molybdenum. Molybdenum strengthens the solid solution during heat treatment, while chromium and vanadium form carbides that keep the hardness during tempering. | 0.48–0.56 | 0.15–0.40 | 0.70–1.00 | ≤ 0.035 | ≤ 0.035 | 0.90–1.20 | 0.15–0.30 | 0.07–0.12 | – |
| Stainless spring steel (approved for aerospace) | X10CrNi18-8, 1.4310, AISI 301 / 302 | Stainless spring steel with good ductility. Non-magnetic when annealed, but it becomes partly magnetic when cold worked (as spring strip is). Designed for aircraft parts, and also used in the chemical and food industries for pump parts, acid tanks and high-temperature springs: in the food, fruit, vegetable and chemical industries, nitrogen plants (valves, fittings and pumps), coal and petrochemical industries, distillation boilers, agitators, heat exchangers, absorption towers and pipelines. Very good weldability, with no preheating needed. | 0.05–0.15 | ≤ 2.00 | ≤ 2.00 | ≤ 0.045 | ≤ 0.015 | 16.0–19.0 | ≤ 0.80 | – | 6.0–9.5 |
Compositions are typical limits from EN 10132-4, EN 10089 and EN 10151. Always check the mill certificate for the actual heat.
Corrosive, hot or magnetic environment?
Tell us the operating conditions and we’ll recommend the right material and recalculate your disc spring in it.