Materials

Aluminum Alloys

Alloy Temper Ductility Strength Corrosion Resistance Heat Treatable Comments
6061 T6 Low Mid Good No Minimum bend radii of 3x raw material thickness.
6061 T0 High Low Good Yes Higher-cost heat treating due to warping and need for secondary straightening.
5052 H32 High Mid Good No Most commonly used aluminum alloy and temper.
5052 H34 Mid High Good No Small radii bends in line with grain may fracture.
3003 H14 High Low Good No Good for deep drawn parts.

Stainless Steel

Alloy Temper Ductility Strength Corrosion Resistance Heat Treatable Comments
301
302
304		 *Range **High High Excellent No Small radii bends in line with grain may fracture in full hard temper. Full hard temper is cost effective for springs as there is no need for heat treating or plating.
316
316L		 Annealed High High Excellent No Used heavily in the medical industry.
410 Annealed High Mid Mid Yes Excellent for springs. Stays stable in heat treating and has a bright finish.
17-4 PH Annealed Low Excellent Mid Yes Small radii bends in line with grain may fracture.
17-7 PH
Cond. A		 Annealed Mid High Mid Yes Excellent for springs intended for repeated cycles. Remains stable during heat treating.
17-7 PH
Cond. C		 Mill Hardened Low High Mid Yes Small radii bends in line with grain may fracture. Highest hardness and strength achievable in alloy 17-7 PH.
*Annealed, 1/2, 1/4, 3/4, and full hard possible
** Ductility decreases in harder tempers and mill hardened materials

Low Carbon and Spring Steel

Alloy Temper Ductility Strength Corrosion Resistance Heat Treatable Comments
1008
1010		 Soft, 1/2, 1/4 Full Hard High Mid *Poor **Yes When rolled at or near room temperature, excellent ductility and strength is produced and is more uniform than hot rolled steel.
1008
1010		 Annealed High Mid *Poor **Yes Rolled at a temperature greater than the recrystallization point, which produces surface scale. Good ductility, but weaker and less uniform than cold rolled steel.
HSLA Annealed Mid High *Poor **Yes Requires 25-30% more power to form than cold rolled steel or hot rolled steel.
1050
1074
1075
1095		 Annealed Excellent ***High *Poor Yes 1095 has the highest carbon content of the materials listed. Higher carbon content yields higher strength with less ductility after heat treating.
1095 Blue Tempered Low High Mid No Good for flat springs or leaf springs with large radii.
*Poor without plating or surface treatment
** Limited to carburizing
*** High strength after heat treatment

Copper Alloys

Alloy Temper Ductility Strength Corrosion Resistance Heat Treatable Comments
C110 Copper Wide Range High Mid Good No Highly conductive. High cost.
C172 Beryllium Copper Wide Range Excellent Excellent Fair Yes Excellent for electrical spring contacts. Highly conductive, excellent electroplating adhesion coefficient and remains very stable during heat treating. Moderate cost.
C260 Brass Wide Range *Ranges High Good No Small radii bends in line with grain may fracture in full hard and spring tempers.
C510 Phosphor Bronze Wide Range *Ranges High Fair No Small radii bends in line with grain may fracture in full hard and spring tempers.
*Ranges according to temper

Raw Materials Selection

Heat Treatable Alloys

When stiffness and spring characteristics are required, the design engineer should consider the following: For parts with small radius forms, high carbon spring steel or another heat treatable metal with good ductility may need to be used. The part may require heat-treating after forming to achieve necessary stiffness or spring performance characteristics, which adds to manufacturing cost. Note that broad flat sections in high carbon spring steel parts tend to warp during heat treating. Where potential warping may be a factor, it is wise to consider alternate materials that may have a marginally higher cost but stay more stable during heat treating.
  • 410 Stainless Steel
  • 17-7 PH Stainless Steel, condition A (annealed)
  • C172 Beryllium copper
  • Low Carbon Cold Rolled Steel – carburizing hardens the surface while reducing spring characteristics

Mill Hardened Alloys

For flat parts or parts with large radius form features, a mill-hardened alloy may be selected based on hardness or spring performance characteristics to eliminate the need for heat treating.
Consider the following:
  • 6061 Aluminum in T4 or T6 temper
  • 300 series Stainless Steel in 1/4, 1/2, 3/4 or full hard temper
  • 1095 blue temper spring steel
  • C110 Copper and C260 Brass in H04 (hard), H06 (extra hard), H08 (spring temper) and H10 (extra spring temper)
  • C510 Phosphor Bronze in H06 (extra hard), H08 (spring temper) and H10 (extra spring temper) Note that raw material grain impacts forming characteristics in all materials, but more so in mill-hardened alloys.
 
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