Articles

Picking the right alloy is a critical part

of the PCS manufacturing process

Titanium space saving alloy wire classesTitanium produces up to 30 percent in weight and space savings but can be costly and difficult to fabricate.

 
One of the most important steps in Precision Coil Spring's manufacturing process is determining the right alloy to use for a particular application.  This choice will depend on the operating requirements of the application, including the spring function and the environment.
 
Functional requirements include load and load operating cycle, cycle frequency, long-term reliability, and fatigue life. 
 
Operating requirements are temperature, corrosion, and consideration for potential dissimilar metals in adjoining components.
 
Alloy wire classes for springs include:
 
Carbon steel
Includes music wire, hard drawn, oil tempered
Used extensively in commercial applications
Can be plated
Useful in ambient conditions
Most economical
 
Alloy steel
Includes chrome silicone and chrome vanadium
Higher strength than carbon steel
Improved fatigue life
Typically, better impact resistance
Operating temperature to 350 F
Plating not recommended
Nominal cost increase over carbon steel
 
Stainless steel - 300 series - cold drawn
Most popular corrosion resistant alloy in normal atmosphere when passivated
Lower strength than carbon steel
Operating temperature to 350 F
Most economical of stainless steel alloys
 
Stainless steel - precipitation hardened
17-7PH is most popular spring alloy
Higher strength, after heat treat, than 300 series
Operating temperature to 550 F
Better long-term stability and fatigue than 300 series
Higher cost
 
Nickel-based
Wide selection of alloys for specific applications; examples include Inconel X750, Inconel 718, Inconel 600, Hastelloy, monel
Most are precipitation hardened
Operating temperature range is from -300 F to 1000 F, depending on alloy
Some alloys are sea water corrosion resistant
Some alloys are good for cryogenic applications
Substantial cost increase over most other alloys
 
Cobalt-based
Similar characteristics as nickel-based
More corrosive resistant in chlorine and sulfur environments
 
Copper-based
Includes brass, phosphorous bronze, beryllium copper
Best conductivity of all alloys
Used in electrical and electronic applications
Can be plated
 
Titanium
Up to 30 percent weight and space savings (low modulus)
Good fatigue life when shot-peened
Corrosion resistant (an exception being a chlorine environment)
Variety of grades for many requirements, including in-body medical applications
Difficult to fabricate
Costly
 
To determine which alloy is best for your application, Ask a PCS Engineer.
 
 
 

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