| Property | Value |
|---|---|
| Name | Alloy 32-5 / Super Invar |
| Type | Controlled Expansion Alloy |
| Chemical Sign | 64 Fe – 31 Ni – 5 Co |
| Specific Gravity | 8.15 |
| Density (lb/cu in) | 0.294 |
| Density (kg/cu m) | 8150 |
| Electrical Resistivity (RT) microhm.cm | 80 |
| Modulus of Elasticity x 10(6) PSI | 21 |
| Modulus of Elasticity x 10(6) MPa | 144 |
| MS Temperature °C | -80 |
| MS Temperature °F | -112 |
| Poisson's Ratio | 0.2 |
| % Elongation in 2" | 40 |
SUMMARY PROPERTIES
COMPOSITION - ALLOY 32-5 / SUPER INVAR
| Substance | Symbol | % |
|---|---|---|
| Nickel | Ni | 31.75 |
| Cobalt | Co | 5.36 |
| Chromium | Cr | 0.03 |
| Manganese | Mn | 0.39 |
| Silicon | Si | 0.09 |
| Carbon | C | 0.05 |
| Aluminium | Al | 0.07 |
| Copper | Cu | 0.08 |
| Sulpur | S | 0.01 |
| Iron | Fe | Balance |
COEFFICIENT OF THERMAL EXPANSION - ALLOY 32-5 / SUPER INVAR
| Temp Range | Value [ cm per cm. C X 10(-6) ] |
|---|---|
| -55 to 95 °C | 0.63 |
| -67 to 203 °F | 0.35 |
TENSILE STRENGTH & YIELD - ALLOY 32-5 / SUPER INVAR
| Property | 0.2% Yield Strength | Tensile Strength |
|---|---|---|
| KSI | 40 | 70 |
| MPa | 276 | 483 |
HARDNESS (Rockwell B) - ALLOY 32-5 / SUPER INVAR
| Property | Value |
|---|---|
| Annealed | 75 |
| Cold Worked | 90 |
MACHINING - ALLOY 32-5 / SUPER INVAR
Machinability
Super Invar 32-5 machines similar to, but not as well as , Type 316 austenitic stainless steel. Its machinability rating is approximately 25% that of AISI B1112. This alloy is somewhat difficult to machine because the machined chips are gummy and stringy. Work hardened bars can result in some improvement in machinability.
Tool geometries normally used for austenitic stainless steels are suitable for this alloy. All tools should be kept sharp with a fine finish, be as large as possible, and rigidly supported.
Recommended cutting fluids are 1 to 1 blend of sulfachlorinated petrolum oil containing 8 to 10% fatty oil and a paraffin blending oil, or a water emulsifiable cutting fluid with polar and extreme pressure additives.
Parts should be degreased and cleaned as soon after machining as possible to remove any residual sulfur which can cause grain boundary embrittlement.
When using carbide tools, surface speed feet/minute can be increased between 2 to 3 times over the high speed suggestions. Feeds can be increased between 50 to 100%.
On certain work, the nature of the part may require adjustment of speeds and feeds. Each job has to be developed for best production results with optimum tool life. Speeds and feeds should be increased or decreased in small steps.
Forging
Suggested forging temperature is 2000/2150°F. Heat rapidly and avoid soaking in the forging furnace. Long soaking time may result in a checked surface due to oxygen and sulfur contamination.
Grinding
A soft silicon carbide wheel which will wear without loading is recommended. For finishing grinding, a satisfactory wheel roughness to start with is No. 80 grit.
