| Invar (36% NI-Balance Iron) Alloy has been the metal of choice for low expansion applications for years. "Super-Invar" (31% NI-5% Co-Balance Iron) has found some favor because it has a near zero coefficient of thermal expansion over a limited temperature range. The useful range of "Super Invar" is limited to between -32° to + 275°C. because the material begins to transform from Austenite to Martinsite at temperature below-32°F |
Physical Properties
| Density |
0.294 lb/cubic in |
| Hardness |
77 RB |
| Tensile Strength |
69800 psi |
| Yield Strength |
43900 psi |
| Elongation 2" |
38% |
| Modulus of Elasticity |
21.5 x 10 psi |
| Polasons Raatio |
.234 | |
To develop the lowest coefficient of thermal expansion the following heat treatment is recommended
| 1525°F 10 min @temperature |
water quench or rapid air cool |
| 600°F 60 min @ temperature |
air cool |
| 212°F 24 hours@ temperature |
air cool | |
Thermal Expansion
| Temp deg F |
Coeff of Expansion |
| 0°F-50°F |
02. x 10(-6) in/IN/deg f |
| 50°F-100°F |
05. x 10(-6) in/IN/deg f |
| 100°F-150°F |
01. x 10(-6) in/IN/deg f |
| 150°F-200°F |
07. x 10(-6) in/IN/deg f | |
The C.T.E crosses over the zero frequently, each lot of heat behaves a little differently, but these results are typical for material between 0°F and 200°F
Formability: Super Invar is easily formed, deep drawn and fabricated.
Weldability: Super Invar is welded using a special Super Invar weld wire, and a variety of other high nickel rods and wires |
Chemistry: Typical Analysis
| C |
S |
Si |
Mn |
Ni |
Cr |
Cu |
Ai |
Co |
| .05 |
.01 |
.09 |
.39 |
31.26 |
.03 |
.08 |
.07 |
5.36 | |
Machinability: Super Invar is tough and gummy, not hard or abrasive. Tools tend to plow instead of cut, resulting in long stringy "chips." Tools must be sharp, feed and speed low to avoid heat and distortion. The use of a coolant is recommended for all machining operations. Machinability similar to Kovar, Stainless 300 series, and Monel Alloys has been reported. Ni-Fe Alloys generally have a tendency to develop a surface scale during hot working that penetrates the surface. For this reason machining allowances must be increased to eliminate the deep surface oxide. The initial cut is frequently the most difficult. |
|
Typical Linear Coefficient of Thermal Expansion
( cm per cm. c x 10 -6 )
| 30 to 100 |
9.4 |
| 30 to 200 |
9.4 |
| 30 to 300 |
8.8 |
| 30 to 350 |
9.0 |
| 30 to 400 |
8.7 |
| 30 to 425 |
8.9 |
| 30 to 450 |
9.0 |
| 30 to 500 |
9.4 |
| 30 to 550 |
10.2 |
| 30 to 600 |
10.4 |
| 30 to 700 |
11.3 |
| 30 to 800 |
12.1 |
| 30 to 900 |
13.0 |
| 30 to 1000 |
13.9 | |
|
Alloy 52
Nominal Data Sheet
Typical Nominal Chemistry
| Nickel (Ni) |
50.5 |
| Chromium (Cr) |
0.10 |
| Manganese (Mn) |
0.60 |
| Silicon (Si) |
0.30 |
| Carbon (C) |
0.05 |
| Aluminum (Al) |
0.10 |
| Magnesium (Mg) |
0.50 |
| Zirconium (Zr) |
0.00 |
| Titanium (Ti) |
0.00 |
| Phosphorus (P) |
0.025 |
| Sulfur (S) |
0.025 |
| Iron |
Balance | |
Typical Linear Coefficient of Thermal Expansion
( cm per cm. c x 10 -6 )
| 30 to 100 |
10.5 |
| 30 to 200 |
10.4 |
| 30 to 300 |
10.2 |
| 30 to 350 |
10.2 |
| 30 to 400 |
10.1 |
| 30 to 425 |
NA |
| 30 to 450 |
10.1 |
| 30 to 500 |
10.0 |
| 30 to 550 |
10.5 |
| 30 to 600 |
10.8 |
| 30 to 700 |
11.7 |
| 30 to 800 |
12.5 |
| 30 to 900 |
13.3 |
| 30 to 1000 |
14.2 | |
Alloy 52
Nominal Data Sheet
Typical Nominal Chemistry
| Nickel (Ni) |
50.5 |
| Chromium (Cr) |
0.10 |
| Manganese (Mn) |
0.60 |
| Silicon (Si) |
0.30 |
| Carbon (C) |
0.05 |
| Aluminum (Al) |
0.10 |
| Magnesium (Mg) |
0.50 |
| Zirconium (Zr) |
0.00 |
| Titanium (Ti) |
0.00 |
| Phosphorus (P) |
0.025 |
| Sulfur (S) |
0.025 |
| Iron |
Balance | |
|
Typical Linear Coefficient of Thermal Expansion
( cm per cm. c x 10 -6 )
| 30 to 100 |
10.5 |
| 30 to 200 |
10.4 |
| 30 to 300 |
10.2 |
| 30 to 350 |
10.2 |
| 30 to 400 |
10.1 |
| 30 to 425 |
NA |
| 30 to 450 |
10.1 |
| 30 to 500 |
10.0 |
| 30 to 550 |
10.5 |
| 30 to 600 |
10.8 |
| 30 to 700 |
11.7 |
| 30 to 800 |
12.5 |
| 30 to 900 |
13.3 |
| 30 to 1000 |
14.2 | | |
Technical Data