4J78 Precision Alloy Steel Bar


4J78 alloy permeability is low, and other non-magnetic ceramic seal than the lower coefficient of expansion, it is called non-magnetic fixed expansion porcelain seal. Add a small amount of copper alloy, can improve its processing performance. The alloy's porcelain enamel composite is superior to Monel, stainless steel, oxygen-free copper and other non-magnetic porcelain sealing materials. Mainly used as electrical vacuum devices in the non-magnetic ceramic sealing material.


4J78 Organizational structure:

1,4 J78 phase transition temperature

2,4J78 Time - Temperature - Tissue Transition Curve

3,4J78 alloy structure: In the Ni-Mo phase diagram, the alloy in the two-phase region. Under equilibrium condition, the alloy is α-phase above 770 ℃. When the temperature is lower than 770 ℃, β-phase precipitates from the α-phase and becomes α + β two-phase. The β phase is an intermediate compound, Ni4Mo, which has a dispersion-hardening effect in the α phase. However, in the alloy heat treatment under the conditions of a single austenitic alloy organization. When the total cold strain rate of 60% to 70% of 1mm thick strip, annealed at the temperature shown in Table 4-1, after air cooling, according to YB027-1992 grain size rating,

Annealing temperature / ° C 850 900 950 1000 1050 1100

Grain size class 9 8 7 6 5.5 4


4J78 process performance and requirements:

1,4J78 Formability: Alloy has good processability and deep drawing extension performance. After the proper heat treatment of the alloy strip, the grain size grade is 5 to 6 grades, and the Vickers hardness should be 174 to 207, so as to facilitate the deep drawing extension of the part.

2,4J78 Welding performance: Alloy welding can be used.

3,4J78 parts heat treatment process: Alloy cold strain intermediate annealing should be heated in hydrogen (or vacuum) to 1050 ~ 1080 ℃, heat 40min, water quenching. In order to obtain a lower hardness value, the heat treatment temperature may be appropriately increased.

4,4J78 Surface treatment process: Surface treatment can be sandblasting, polishing, pickling.

5,4J78 cutting and grinding performance: Alloy carbide cutting tools can be used. Grinding performance is better.


4J78 variety specifications and supply status:

1, the species classification: Shanghai Baoyu special alloy can produce a variety of seamless pipe, steel, round steel, forgings, flanges, rings, pipe, strip, wire and supporting welding consumables.

2, the delivery status: seamless pipe: solid solution + acid white, the length can be length; plate: solid solution, pickling, trimming; pipe: solid solution acid white RT% flaw detection, Bar to wrought state, the surface polished or car light; strip by cold-rolled, solid solution soft state, to the oxide skin delivery; wire to solid acid pickling pan or straight strip, solid solution straight fine grinding Light status delivery.

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