Type Analysis | Description | Applications | Physical Properties
Heat Treatment | Workability | Typical Mechanical Properties

Type Analysis

Description

Alloy 42 is a 41% nickel-iron controlled expansion alloy which has been used in a wide variety of glass-to-metal sealing applications.
While the expansion properties of this alloy most closely match 1075 glass, it has also been used in seals for the 0120 and 0010 glasses. It may also be used with hard glasses if a thin edged tubular seal is used. For seals that are not hydrogen annealed prior to sealing, a variation of this alloy containing small additions fo titanium, Glass Sealing 42 Gas-Free, has been used to promote gas-free sealing characteristics.

Applications

Alloy 42 has been used for the glass-to-metal seals in electronic tubes, automotive and industrial lamps, transformer and capacitor bushings and other glass-to-metal and ceramic-to-metal applications.

Physical Properties

Specific gravity ......................................... 8.12                            Inflection Point
Density                                                                                              °F............................................ 650
   lb/cu in .................................................. 0.293                              °C ........................................... 343
Thermal conductivity                                                                    Curie Temperature
   Btu-in/ft²/°F.............................................74.5                                 °F............................................ 715
   W/m-K (20/100°C)................................ 10.7                                  °C .......................................... 380
Electrical resistivity                                                                         Melting Point
   ohm-cir mil/ft .......................................... 400                                °F.......................................... 2600
   microhm-cm............................................ 66                                 °C.......................................... 1427
Temperature coefficient of electrical                                               Specific heat
   resistivity                                                                                          Btu/lb-°F.............................. 0.12
   per °F(70/212°F)................................. 0.0006                                 kJ/kg-K ................................ 0.50
   per °C(20/100°C) ................................... 0.001                             Modulus of elasticity
Mean coefficient fo thermal expansion                                               psi x 10(6) .............................. 21.5
   10(-6)/°F(86 to 572°F) ......................... 2.2-2.6                              MPa x 10(3) .......................... 148.4     
                  (86 to 842°F) ......................... 3.7-4.1
   10(-6)/°C(30 to 300°C) ........................ 4.0-4.7
                   (30 to 450°C) ........................ 6.7-7.4

Heat Treatment

Annealing
Heat to 1450°F (788°C) and hold at heat for at least one-half hour per inch of thickness, air cool.

Workability

Forging
The forging temperature should be 2150/2200°F (1177/1204°C). Avoid prolonged soaking to prevent sulfur absorption from the furnace atmosphere.

Cold Heading
Glass Sealing 42 may be swaged or cold upset.

Blanking or forming
For clean blanking of Glass Sealing 42, a Rockwell hardness of about B90 is suggested. Where any sharp bends are involved in forming finished parts from strip or rods, a hardness of not over Rockwell B93 is suitable.

Grinding
A silicon carbide wheel is desirable, preferably a soft wheel which will wear without loading. For finish grinding, a satisfactory grade to start with is No. 80 grit.

Welding
Any of the conventional welding methods can be used. When filler rod is required, Glass Sealing 42 is suggested.

Typical Mechanical Properties

Material in the annealed condition.

Invar 42 - Current Inventory Stock