Are all Coil springs work hardened so that annealing will reduce their stiffness? 4

[vonsteimel]

I was just wondering if coil springs relied partially on work-hardened wire to give them their "spring" properties or is it simply the property of spring steel?

so that if one were to heat/anneal a coil spring, would it lose much of its stiffness/spring properties?

What about machined coil springs? Are they machined out of work-hardened round stock (CRS maybe?) or again, is it simply a property of the spring steel so that annealing will not affect its spring/stiffness?

Just wondering this as I was doing some work with them.

VS

 

[btrueblood]

For spring wire, high shear yield strength (and high fatigue limit in torsion) more specifically; the values for spring wire can be higher than what isotropic material theory would indicate (i.e. more than Von Mises' or Tresca theory predicts from tensile yield strength) - this happens partially to the non-isotropic nature of drawn wire. Doing so with minimal or no expensive alloying elements is a big plus for near-commodity items like coil springs.

 

[Tmoose]

I think at some level steel cleanliness becomes important to buy fatigue life too. At least Isky said so once upon a time.

 

[tbuelna]

So... What properties are they trying to obtain in spring steel that differ from mild steel or tool steel.etc What makes a good spring steel?

vonsteimel,

The best material for a particular spring design can depend on many things. Most springs are made from heat-treatable alloy steels, but some are made from non-heat treatable, work hardening steels like 302/304 austenitic stainless. The best material choice for a given application would be based on requirements such as fatigue life, operating temperature, corrosion resistance, cost, etc.

Hope that helps.
Terry

 

[mfgenggear]

can some give actual example's.


Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[drawoh]

mfgenggear,

I designed a Belleville spring out of Delrin, to work a a lens pre-loader. I wanted lots of deflection, low force, and no scratched glass.

Belleville springs are explained in Roark's Equations for Stress and Strain, as well as in an SAE Spring manual I have.

--
JHG