4J42 Precision Alloy Steel Bar


4j42 precision Iron-nickel alloy is a series of fixed-expansion alloys which can be matched with soft glass and ceramics with different expansion coefficients in a given temperature range by adjusting the nickel content. The expansion coefficient and the Curie point increase with increasing nickel content. The alloy is widely used in the vacuum industry, sealing structure materials.


4J42 organizational structure:


1,4J42 Phase transition temperature:

2,4J42 Time - Temperature - Tissue Transition Curve:

3,4J42 alloy structure: the group of gold are stable austenitic tissue.

4,4J42 Grain size: The grain size of the deep-drawn alloy strip shall not be less than 7, and the grain size of less than 7 shall not exceed 10% of the area. When the average grain size of the strip less than 0.13 mm in thickness is estimated, the number of grains along the thickness of the strip shall not be less than eight.


4J42 process performance and requirements:


1,  4J42 Formability: This alloy is very cold and hot. Hot processing temperature should not be too high, heating time should not be too long, should avoid heating in a sulfur-containing atmosphere. When the tape cold strain rate greater than 75%, will cause plastic anisotropy after annealing. Cold strain rate of 10% to 15%, heated to 950 ~ 1050 ℃ (during the brazing process) significant grain growth, resulting in reduced plasticity of the alloy, the thin section may also lose the metal vacuum tightness . Therefore, the final product strain rate should be controlled at about 60%.


2,  4J42 Welding performance: The alloy has good welding performance, brazing and spot welding. The alloy should be pre-oxidized before sealing with soft glass and other materials.

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 after machining parts to be stress relief annealing: 430 ~ 540 ℃, heat 1 ~ 2h, furnace cooling or air cooling.


(2) intermediate annealing: In order to eliminate the work-hardening phenomenon caused by the alloy in cold rolling, cold drawing and cold stamping process, in order to facilitate the further processing. Workpieces to be in a vacuum or protective atmosphere, heated to 700 ~ 800 ℃, holding 30 ~ 60min, and then furnace cooling, air cooling or water quenching.


(3) Pre-oxidation treatment: When the alloy is used as sealing material, it should be pre-oxidized before sealing. The alloy surface Health


Into a layer of uniform thickness, dense oxide film. The parts were heated in saturated wet hydrogen at 1100 ° C for 30 min and then oxidized in air at about 800 ° C for 5-10 min. Part weight gain 0.1 ~ 0.3mg / cm2 is appropriate.


The alloy can not be hardened with heat treatment.


4,4J42 Surface treatment: Before heat treatment, welding or glass sealing, the metal surface dirt and grease must be removed. Serious oxide layer can be used when sandblasting or immersion in the molten alkali, and then pickling. Slight oxide scale with 25% hydrochloric acid solution at 70 ℃ pickling.

5,4J42 Machining and Grinding Properties: This alloy is similar in machinability to austenitic stainless steel. When processing high-speed steel or carbide cutting tools, low-speed machining, cutting coolant can be used. Grinding performance is good.


4J42 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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