Miniature Spring Materials

Common Materials & Specifications for Mechanical Micro Springs

Micro and miniature springs are essential components in precision engineering, offering flexibility, resilience, and durability in compact applications. Choosing the right material and specifications is crucial for optimal performance in industries such as medical devices, aerospace, and electronics. This page provides a comprehensive overview of the most commonly used materials—including stainless steel and specialty alloys—along with key specifications that determine a micro spring’s strength, corrosion resistance, and functional lifespan. Explore the details below to find the best fit for your specific application.
Learn About Micro Spring Finish Options

Material Properties

High Carbon Steels
Material Commercially Available Specification Nominal Chemistry Density (lb/in3) Minimum Tensile Strength (psi x 103) Modulus of Elasticity (E)(psi x 106) Modulus in Torsion (G)(psi x 106) Maximum Operating Temperature Description & Primary Use
Oil Tempered MB ASTM A229 C 0.55 - 0.85%, Mn 0.30 - 1.20% 0.28 Class I: 165 - 293, Class II: 191 - 324 30 11.5 250 °F General purpose spring wire for average stress applications. Highly magnetic. Often used for larger wire sizes when Music Wire is not available.
Hard Drawn MB ASTM A227 C 0.45 - 0.85%, Mn 0.30 - 1.30% 0.28 Class I: 147 - 283, Class II: 171 - 324 30 11.5 250 °F General purpose spring wire for low to average stress applications. Cold drawn to desired properties. Highly magnetic.
Music Wire ASTM A228 C 0.70 - 1.00%, Mn 0.20 - 0.70% 0.28 230 - 399 30 11.5 250 °F High quality spring wire that is cold drawn with good surface finish. Highly magnetic. Generally good fatigue life due to high tensile strength.
Alloy Steels
Material Commercially Available Specification Nominal Chemistry Density (lb/in3) Minimum Tensile Strength (psi x 103) Modulus of Elasticity (E)(psi x 106) Modulus in Torsion (G)(psi x 106) Maximum Operating Temperature Description & Primary Use
Oil Tempered Chrome Vanadium ASTM A231 C 0.48 - 0.53%, V 0.15 Min %, Mn 0.70 - 0.90%, Cr 0.80 - 1.10% 0.28 190 - 300 30 11.5 425 °F Alloy steel spring wire used for shock loads and moderately elevated temperatures. Highly magnetic. Available in Valve Spring quality in accordance with ASTM A232.
Oil Tempered Chrome Silicon ASTM A401 C 0.51 - 0.59%, Cr 0.60 - 0.80%, Si 1.20 - 1.60% 0.28 224 - 300 30 11.5 475 °F Alloy steel spring wire used for shock loads and moderately elevated temperatures. Highly magnetic. Available in Valve Spring quality in accordance with ASTM A877.
Stainless Steels
Material Commercially Available Specification Nominal Chemistry Density (lb/in3) Minimum Tensile Strength (psi x 103) Modulus of Elasticity (E)(psi x 106) Modulus in Torsion (G)(psi x 106) Maximum Operating Temperature Description & Primary Use
Stainless Steel 17-7 PH AMS 5678 Cr 16.0 - 18.0%, Ni 6.5 - 7.7%, Al 0.75 - 1.5% 0.28 Cond. CH900: 230 - 343 29.5 11 650 °F Improved strength over 300 Series stainless steels with similar heat and corrosion resistance. Slightly magnetic. Material is precipitation hardened after spring fabrication to achieve desired properties.
Stainless Steel 316 ASTM A313 Cr 16.5 - 18.0%, Ni 10.5 - 13.5%, Mo 2.0 - 2.5% 0.29 125 - 245 28 10 550 °F General heat resistant spring wire and better corrosion resistance than Type 302/204. Slightly magnetic. Often used in marine applications, resists chloride attack.
Stainless Steel 302/304 ASTM A313 Cr 17.0 - 20.0%, Ni 8.0 - 10.5% 0.29 130 - 325 28 10 550 °F General purpose corrosion and heat resistant spring wire. Slightly magnetic. Type 304 has less carbon than Type 302, however considered commercially equivalent for stock springs.
Copper Alloys
Material Commercially Available Specification Nominal Chemistry Density (lb/in3) Minimum Tensile Strength (psi x 103) Modulus of Elasticity (E)(psi x 106) Modulus in Torsion (G)(psi x 106) Maximum Operating Temperature Description & Primary Use
Monel K 500 QQ-N-286 Ni 63.0 min%, Cu 27.0 - 33.0%, Al 2.3 - 3.1% 0.31 160 - 200 26 9.5 500 °F Similar corrosion and heat resistance to Monel 400 with better strength. Good for subzero and cryogenic applications.
Monel 400 AMS 7233 Ni 63.0 min%, Cu 28.0 - 34.0% 0.32 145 - 180 26 9.5 450 °F Nickel-copper alloy spring wire with good corrosion resistance at moderately elevated temperatures. Good mechanical properties for subzero temperature applications. Generally resistant to hydrofluoric, sulfuric, and hydrochloric acids. Typical for marine and chemical processing applications.
Brass ASTM B134 Cu 68.5 - 71.5%, Zn 28.5 - 31.5% 0.31 120 min 16 6 200 °F Good combination of strength and ductility for cold working. Properties based on 70-30 Spring Brass (C26000) sub-type. Used in fresh water and seawater applications.
Beryllium Copper ASTM B197 Cu 98.0%, Be 1.8 - 2.0% 0.30 160 - 230 18.5 7 400 °F Non-ferrous spring wire with good corrosion resistance and electrical conductivity. Improved strength over phosphor bronze and non-magnetic. Material is precipitation hardened after spring fabrication to achieve desired properties.
Phosphor Bronze ASTM B159 Cu 94.0 - 96.0%, Sn 4.0 - 6.0% 0.32 105 - 145 15 6.25 200 °F Non-ferrous spring wire with good corrosion resistance and electrical conductivity. Non-magnetic.
Nickel Alloys
Material Commercially Available Specification Nominal Chemistry Density (lb/in3) Minimum Tensile Strength (psi x 103) Modulus of Elasticity (E)(psi x 106) Modulus in Torsion (G)(psi x 106) Maximum Operating Temperature Description & Primary Use
Hastelloy (C276) ASTM B574 Ni 51.0 - 63.5%, Cr 14.5 - 16.5%, Mo 15.0 - 17.0%, Fe 4.0 - 7.0% 0.32 100 - 200 30.7 11.8 700 °F Good corrosion resistance in chemical process environments. Known for excellent resistance to sulfur and chloride compounds. Useful in marine and waste treatment industries.
NiSpan C AMS 5225 Fe 45.0 - 51.0%, Ni 41.0 - 43.5%, Cr 4.9 - 5.75%, Ti 2.25 - 2.75%, Al 0.3 - 0.8% 0.29 150 - 190 24.0 - 29.0 9.0 - 10.0 150 °F Special alloy that is heat-treatable to have a constant modulus over a range of operating temperatures. Material is not stainless and is magnetic. Typically used in timing devices, weighing and geophysical instruments.
Elgiloy AMS 5833 Co 39.0 - 41.0%, Ni 15.0 - 16.0, Cr 19.0 - 21.0%, Fe 15.0 - 18.0% 0.30 270 - 300 32 12 850 °F Cobalt-Nickel alloy known for strength and non-magnetic qualities. Excellent corrosion resistance, good for acetic acid, ammonium chloride, citric acid, sodium chloride and sodium sulfite. Material is precipitation hardened after spring fabrication to achieve desired properties.
Inconel X750 AMS 5698 / 5699 Ni 70.0 min%, Cr 14.0 - 17.0%, Fe 5.0 - 9.0% 0.30 No. 1 Temper: 155 Min, Spring Temper: 180 - 220 31 12 750 - 1100 °F Better strength over Inconel 600. Material is precipitation hardened after spring fabrication to achieve desired properties. No. 1 Temper provides better heat resistance.
Inconel 718 ASTM B637 Ni 50.0 - 55.0%, Cr 17.0 - 21.0%, Fe 11.0 - 24.0% 0.30 210 - 250 29 11.2 1100 °F Better strength and heat resistance over Inconel 600. Material is precipitation hardened after spring fabrication to achieve desired properties.
Inconel 600 ASTM B166 Ni 72.0 min%, Cr 14.0 - 17.0%, Fe 6.0 - 10.0% 0.31 140 - 185 31 11 700 °F Good corrosion resistance and mechanical properties at moderately elevated temperatures. Also good for cryogenic applications. Used in chemical processing, heat-treating, and aerospace industries.