Common Metal Spring Materials

Metal springs are manufactured from various materials, each with distinct properties that impact their performance and durability. Selecting the right material is crucial for ensuring the optimal function of the spring. The three most common spring materials are music wire, stainless steel, and chrome silicon alloy, each offering unique advantages and limitations depending on the application.

1. Music Wire

Music wire (ASTM A228) is the most widely used material in spring manufacturing. It offers high strength and cost-effectiveness, making it an ideal choice for general applications.

Key Characteristics:

• Maximum Operating Temperature: 250ºF (121ºC)

• Rockwell Hardness: C41-60

• Density: 7.85 g/cm³

• Tensile Strength: 2200-2500 MPa

• Chemical Composition:

• Carbon (C): 0.70-1.00%

• Manganese (Mn): 0.20-0.60%

• Silicon (Si): 0.10-0.30%

• Phosphorus (P): ≤0.025%

• Sulfur (S): ≤0.025%

Limitations:

• Prone to rusting in humid environments

• Not suitable for moisture-exposed applications

Also referred to as spring steel or piano wire.

2. Stainless Steel

Stainless steel is another common spring material, known for its excellent corrosion resistance and high-temperature durability. The three primary types used in spring manufacturing are:

• Stainless Steel 302 (ASTM A313)

• Stainless Steel 316 (ASTM A316)

• Stainless Steel 17-7 (ASTM A313)

Key Characteristics:

• Maximum Operating Temperature: 550ºF (288ºC)

• Rockwell Hardness: C38-45 (302), C41-47 (17-7)

• Density: 7.90 g/cm³

• Tensile Strength: 1275-1900 MPa

• Chemical Composition (Stainless Steel 302):

• Chromium (Cr): 17-19%

• Nickel (Ni): 8-10%

• Carbon (C): ≤0.15%

• Manganese (Mn): ≤2%

• Phosphorus (P): ≤0.045%

• Sulfur (S): ≤0.030%

Advantages:

• Superior corrosion and moisture resistance

• Ideal for medical devices and high-temperature applications

• Good formability and weldability

Limitations:

• Slightly lower tensile strength compared to music wire

3. Chrome Silicon Alloy

Chrome silicon alloy is a high-strength alloy steel wire and the third most commonly used spring material. Compared to stainless steel, it is stronger and offers better high-temperature resistance than music wire.

Key Characteristics:

• Maximum Operating Temperature: 475ºF (246ºC)

• Rockwell Hardness: C48-53

• Density: 7.85 g/cm³

• Tensile Strength: 2000-2200 MPa

• Chemical Composition:

• Carbon (C): 0.51-0.59%

• Manganese (Mn): 0.60-1.00%

• Silicon (Si): 1.20-1.60%

• Chromium (Cr): 0.60-0.80%

• Phosphorus (P): ≤0.025%

• Sulfur (S): ≤0.025%

Advantages:

• High tensile strength provides greater elasticity and force output

• Excellent fatigue resistance

• Ideal for high-temperature applications

Limitations:

• Prone to rusting in humid environments

• Not recommended for prolonged exposure to moisture

Other Coil Spring Materials

In addition to music wire, stainless steel 302, and chrome silicon alloy, other materials are used for specialized applications, including:

• Oil-Tempered MB (ASTM A229)

• Carbon Valve Steel (ASTM A230)

• Hard Drawn Steel (ASTM A227)

• Stainless Steel 17-7 (ASTM A313)

• Stainless Steel 302 (ASTM A313)

• Stainless Steel 316 (ASTM A316)

• Chrome Silicon Alloy (ASTM A401)

• Phosphor Bronze Grade A (ASTM B159)

• Beryllium Copper (ASTM B197)

Each material has unique properties that make it suitable for different environments and performance requirements. Choosing the right material ensures the durability and efficiency of the spring in its intended application.