4j42 Expansion Precision Alloy Hollow Round Bar For Sealig Structural Material
Product description and application:
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.
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.
4J42 process performance and requirements:
1, 4J42 forming properties: the alloy is easy to carry out cold and hot processing. The hot working temperature should not be too high, the heating time should not be too long, and heating in a sulfur-containing atmosphere should be avoided. When the cold strain rate of the strip is greater than 75%, plastic anisotropy is caused after annealing. The cold strain rate is between 10% and 15%. When heated to 950~1050 °C (inevitable during the brazing process), the crystal grains grow significantly, which causes the alloy to decrease in plasticity. For thin sections, the vacuum tightness of the metal may also be lost. . Therefore, the final strain rate of the finished product should be controlled at around 60% [2, 5].
2, 4J42 welding performance: the alloy has good welding performance, can be brazed and spot welded. The alloy should be pre-oxidized before being sealed with materials such as soft glass.
3, 4J42 parts heat treatment process: heat treatment can be divided into: stress relief annealing, intermediate annealing and pre-oxidation treatment.
(1) Stress relief annealing: In order to eliminate the residual stress of the parts after machining, stress relief annealing is performed: 430 ~ 540 ° C, heat preservation for 1 ~ 2 h, furnace cooling or air cooling.
(2) Intermediate annealing: in order to eliminate the work hardening phenomenon caused by the alloy in the cold rolling, cold drawing and cold stamping process, in order to facilitate the processing. The workpiece should be heated to 700-800 ° C in a vacuum or protective atmosphere, and kept for 30-60 min, then cooled, air cooled or water quenched.
(3) Pre-oxidation treatment: When the combination gold is used as a sealing material, pre-oxidation treatment should be performed before sealing. Make the surface of the alloy
A uniform, dense oxide film. The parts were heated at 1100 ° C in saturated wet hydrogen for 30 min and then oxidized in air at about 800 ° C for 5-10 min. The weight gain of the parts is suitable in the range of 0.1 to 0.3 mg/cm2 .
The alloy cannot be hardened by heat treatment.
4, 4J42 surface treatment process: Before heat treatment, welding or glass sealing, it is necessary to remove dirt and grease on the metal surface. When the oxide layer is severe, it may be sandblasted or first immersed in molten alkali, and then pickled. The slightly scaled skin can be pickled with a 25% hydrochloric acid solution at 70 °C.
5, 4J42 cutting and grinding performance: the alloy's cutting characteristics are similar to austenitic stainless steel. High-speed steel or carbide tools are used for machining, low-speed machining, and coolant can be used for cutting. Good grinding performance.