Havar® is a heat treatable Cobalt base alloy that provides very high strength. The alloy has excellent corrosion resistance and is non-magnetic. Applications have included metal diaphragms for aerospace sensors, metal diaphragms for burst discs, power springs, gap spacers in magnetic heads, and target foils in nuclear physics.
Forming cold rolled Havar requires large radius (90° Bend – 8 X thickness) prior to age hardening. The joining can be accomplished using both welding and soldering techniques.The ultimate endurance life is achieved by heat treating the alloy at 1000°F after 80% cold work. The alloy will retain 75% of room temperature strength up to 950°F (Figure 1).
Available Sizes:
Havar® is available from Hamilton Precision Metals as strip product in thicknesses from 0.0005” to 0.025” (0.0127 mm to 0.635 mm) and widths to 7.5” (190.5 mm). A foil product is available in thicknesses down to 0.000060” and widths of 4.0” (101.6 mm). The material corresponds to UNS R30004.
Nominal Composition
| HAVAR® NOMINAL COMPOSITION |
| Cobalt |
42.0%
|
| Chromium |
19.5%
|
| Nickel |
12.7%
|
| Tungsten |
2.7%
|
| Molybdenum |
2.2%
|
| Manganese |
1.6%
|
| Carbon |
0.2%
|
| Iron |
Balance
|
Mechanical Properties
| HAVAR® MECHANICAL PROPERTIES |
|
|
ANNEALED |
COLD ROLLED
|
COLD ROLLED
HEAT TREATED
|
| Ultimate Tensile Strength |
140,000 PSI |
270,000 PSI |
330,000 PSI
|
| Yield Strength (0.2% Offset) |
70,000 PSI
|
250,000 PSI |
300,000 PSI |
| Elongation in 2” * |
40% |
1% |
1%
|
| Hardness |
RC 25
|
RC50 |
RC60 |
| Modulus of Elasticity (Tension) |
29.5 x 106
PSI
|
- |
- |
*The measured elongation will be less as thickness decreases to 0.002” and less.
These values may be adjusted by control of process variables – consult HPM for desired values.
Physical Properties
| HAVAR® PHYSICAL PROPERTIES |
|
Density
|
0.300 lbs/cu.in.
|
| Melting Point (Approx.) |
1480°C |
| Electrical Resistivity @ R.T. |
92 Microhm·cm |
| Thermal Expansion Coefficient (0° to 50°C) |
12.5 x 10-6/°C
|
| Thermal Conductivity |
13.0 W/m·K
|
| Magnetic Attraction |
None
|
Typical values to guide alloy selection but are not a guarantee of minimum or maximum.