Kovar alloy 4j29

4J29 alloy is also known as Kovar alloy. The alloy has a linear expansion coefficient similar to that of borosilicate hard glass at 20 ~ 450℃, a high Curie point and good low temperature microstructure stability. The oxide film of the alloy is dense and can be well infiltrated by glass. And does not interact with mercury, suitable for use in the instrument containing mercury discharge. It is the main sealing structural material of electric vacuum device. It is used to make Fe-Ni-Co alloy strip, bar, plate and pipe with hard glass/ceramic matching sealing, mostly used in vacuum electronics, power electronics and other industries.
4J29 Application overview and special requirements
The alloy is a typical Fe-Ni-Co hard glass sealing alloy commonly used in the world. It has been used by aviation factory for a long time and its performance is stable. It is mainly used for the glass sealing of electric vacuum components such as emission tube, oscillation tube, ignition tube, magnetron, transistor, sealing plug, relay, integrated circuit lead line, chassis, shell, bracket, etc. In the application, the expansion coefficient of the selected glass and the alloy should be matched. The low temperature tissue stability is strictly tested according to the use temperature. Appropriate heat treatment should be carried out in the processing process to ensure that the material has good deep drawing performance. When using forging material, its air tightness should be strictly checked.
Covar alloy because of the cobalt content, the product is relatively wear-resistant.
It can be easily sealed with molybdenum group glass, and the general surface of the workpiece requires gold plating.
4J29 Formability:
The alloy has good cold and hot working properties, and can be made into various complex shapes of parts. However, heating in sulfur-containing atmospheres should be avoided. In cold rolling, when the cold strain rate of the strip is greater than 70%, the plastic anisotropy will be induced after annealing. When the cold strain rate is in the range of 10% ~ 15%, the grain will grow rapidly after annealing, and the plastic anisotropy of the alloy will also be produced. The plastic anisotropy is minimum when the final strain rate is 60% ~ 65% and the grain size is 7 ~ 8.5.
4J29 Welding properties:
The alloy can be welded with copper, steel, nickel and other metals by brazing, fusion welding, resistance welding, etc. When the zirconium content in the alloy is greater than 0.06%, it will affect the welding quality of the plate and even make the weld crack. Before the alloy is sealed with glass, it should be cleaned, followed by high temperature wet hydrogen treatment and pre-oxidation treatment.
4J29 Surface treatment process: Surface treatment can be sandblasting, polishing, pickling.
After the parts are sealed with the glass, the oxide film generated during the sealing should be removed for easy welding. The parts can be heated to about 70 ℃ in an aqueous solution of 10% hydrochloric acid +10% nitric acid, and pickled for 2 ~ 5min.
The alloy has good electroplating performance, and the surface can be gold-plated, silver, nickel, chromium and other metals. In order to facilitate welding or hot pressing bonding between parts, it is often plated with copper, nickel, gold and tin. In order to improve the conductivity of high frequency current and reduce the contact resistance to ensure the normal cathode emission characteristics, gold and silver are often plated. In order to improve the corrosion resistance of the device, nickel or gold can be plated.
4J29 Cutting and grinding performance:
The cutting characteristics of the alloy are similar to those of austenitic stainless steel. Processing using high speed steel or carbide tool, low speed cutting processing. Coolant can be used when cutting. The alloy has good grinding performance.
4J29 Main specifications:
4J29 seamless pipe, 4J29 steel plate, 4J29 round steel, 4J29 forgings, 4J29 flange, 4J29 ring, 4J29 welded pipe, 4J29 steel band, 4J29 straight bar, 4J29 wire and matching welding material, 4J29 round cake, 4J29 flat steel, 4J29 hex bar, 4J29 size head, 4J29 elbow, 4J29 tee, 4J29 4J29 parts, 4J29 bolts and nuts, 4J29 fasteners, etc.