What is the material of 4j29?

4J29 alloy is also called kovar alloy. The alloy has a linear expansion coefficient similar to that of borosilicate glass at 20 ~ 450℃, high Curie point and good structural stability at low temperature. The oxide film of the alloy is dense and can be well infiltrated by glass. Suitable for use in meters with mercury emission. Is that main seal structural material of electric vacuum device.

1. 1? 4J29 material brand? 4J29 .？

1.2? 4J29 Similar brands are shown in table 1- 1. ?

Table 1- 1. ?

2. 1.2? 4J29 Thermal conductivity? See table 2- 1. ?

Table 2- 1.

Table 2-2. ?

2.4.2? The magnetic properties of 4J29 alloy are shown in Table 2-4. ?

2.5? 4J29 alloy has chemical properties and good corrosion resistance in atmosphere, fresh water and seawater. ?

Table 2-4

Hour/(m2)

B/T

Hour/(m2)

B/T

Hour/(m2)

B/T

eight

0.9× 10-2

80

0.35

2000

1.47

16

2. 1× 10-2

160

0.8 1

4000

1.6 1

24

3.6× 10-2

celebrity

1. 17

40

8.3× 10-2

Eight hundred

1.34

Mechanical properties of 4J29?

3. 1? Performance specified in 4J29 technical standard?

3. 1. 1? The hardness of 4J29 hardness deep drawing steel strip shall comply with the provisions in Table 3- 1. Hardness inspection shall not be carried out when the thickness is not more than 0.2 mm?

3. 1.2? 4J29 tensile strength The tensile strength of wire and strip shall comply with the provisions in Table 3-2. ?

Table 3- 1

situation

δ/mm

Hardness HV

Deep thrust state

& gt2.5

≤ 170

≤2.5

≤ 165

Table 3-2

Status code

situation

σb/MPa

Silk material

deprive

rare

Soft state

& lt585

& lt570

1/4I

1/4 hard state

585~725

520~630

1/2I

1/2 hard state

655~795

590~700

3/4I

3/4 hard state

725~860

600~770

I

Hard state

& gt850

& gt700

3.2? 4J29 Mechanical properties at room temperature and various temperatures?

3.2. 1? The hardness of 4J29 strip with cold strain rate of 50% at different annealing temperatures is shown in Figure 3- 1. ?

3.2.2? The tensile properties of 4J29 alloy (annealed) at room temperature are shown in Table 3-3. At different annealing temperatures, the tensile properties of steel strip with cold rolling strain rate of 50% are shown in Figure 3-2. ?

Table 3-3

σb/MPa

σp 0.2/ MPa

δ/%

520

330

30

3.3? 4J29 Durability and Creep Performance

3.4? 4J29 fatigue performance?

3.5? 4J29 elastic performance?

3.5. 1? 4J29 elastic modulus E= 138GPa. ?

Fourth, 4J29 organizational structure?

4. 1? 4J29 phase transition temperature? The γ→α phase transition temperature is lower than -80℃.

4.2? 4J29 Time-temperature-microstructure transition curve?

4.3? 4J29 alloy structure? After the alloy is treated according to the heat treatment system specified in 1.5, and then frozen at -78.5℃, martensite structure should not appear for 4 hours or more. However, when the alloy composition is incorrect, austenite (γ) will transform into acicular martensite (α) at room temperature or low temperature, and the phase transformation will be accompanied by volume expansion effect. The expansion coefficient of the alloy increases correspondingly, which leads to the sharp increase of internal stress in the seal and even local damage. The main factor affecting the stability of the low temperature microstructure of the alloy is the chemical composition of the alloy. From the Fe-Ni-Co ternary phase diagram, it can be seen that nickel is the main element to stabilize γ phase, and high nickel content is beneficial to the stability of γ phase. With the increase of total deformation rate, the microstructure tends to be stable. Segregation of alloy composition may also cause γ→α phase transition in local areas. In addition, coarse grains will also promote γ→α phase transition. ?

4.4? 4J29 grain size standard stipulates that the grain size of deep-drawn strip shall not be less than grade 7, and the grain size less than grade 7 shall not exceed 10% of the area. When estimating the average grain size of a strip with a thickness of less than 0. 13mm, the number of grains along the thickness direction of the strip should be no less than 8. ?

Thick steel strip with cold strain rate of 60% ~ 70% is annealed 1h at the temperature shown in Table 4- 1, and rated according to Appendix A of YB 027- 1992 after air cooling. See table 4- 1 for its granularity. ?

Table 4- 1

Annealing temperature/℃

675

700

750

Eight hundred

900

1000

1 100

1200

Particle size grade

Start recrystallization

& gt 10

& gt 10

10

7.5

5.0

4.0

3.0

The technical performance and requirements of verb 4J29?

5. 1? 4J29 Moldability? The alloy has good cold and hot workability and can be made into various parts with complex shapes. But heating in a sulfur-containing atmosphere should be avoided. In cold rolling, when the cold strain rate of the strip is greater than 70%, plastic anisotropy will occur after annealing; When the cold strain rate is in the range of 10% ~ 15%, the grain size of the alloy grows sharply after annealing, and the plastic anisotropy of the alloy also occurs. When the final strain rate is 60% ~ 65% and the grain size is 7 ~ 8.5, the plastic anisotropy is the smallest [2,4,7 ~ 9]. ?

See fig. 5- 1 for the relationship between cupping value and thickness of alloy strip.

5.2? 4J29 Weldability Can this alloy be brazed, fused or resistance welded?

Methods Welding with copper, steel, nickel and other metals. When the content of zirconium in the alloy is more than 0.06%,

It will affect the welding quality of argon arc welding and even crack the weld. ?

Before sealing the alloy with glass, it should be cleaned and then treated with high temperature and wet hydrogen.

Mechanism and pre-oxidation treatment. ?

5.3? 4J29 parts heat treatment process heat treatment can be divided into: stress relief annealing,?

Intermediate annealing, purification and degassing treatment and pre-oxidation treatment. ?

(1) Stress relief annealing is very important to eliminate the residual stress of machined parts.

Stress relief annealing: 470 ~ 540℃, heat preservation 1 ~ 2h, furnace cooling or air cooling. ?

(2) Intermediate annealing is used to eliminate lead in the alloy during cold rolling, cold drawing and cold stamping.

Work hardening phenomenon, in order to continue processing. Workpieces need to be dried in hydrogen and decomposed in ammonia.

Or in vacuum, heating to 750 ~ 900℃, keeping the temperature for 65438±04min ~ 65438±0h, and then cooling with the furnace.

Air cooling or water quenching.

(3) After the parts are cleaned and degassed, wet hydrogen treatment is required before pre-oxidation treatment, and oil should be removed before treatment. The work needs to be carried out in saturated wet hydrogen, heated to 950 ~ 1050℃, kept at 10 ~ 30 min, and then cooled in the furnace. ?

(4) Pre-oxidized alloys are generally pre-oxidized after wet hydrogen treatment and before sealing, so that an oxide film with uniform thickness is formed on the alloy surface, which is firmly combined with the matrix and can be well infiltrated with molten glass. After wet hydrogen treatment, the parts are oxidized in air at about 800℃. The weight gain of parts should be in the range of 0.2 ~ 0.4 mg/cm2 [10]. ?

This alloy cannot be hardened by heat treatment.

5.4? 4J29 surface treatment process The surface treatment can be sandblasting, polishing and pickling.

After the parts are sealed with glass, in order to facilitate welding, it is necessary to remove the oxide film produced during sealing. Parts can be heated to about 70℃ in the aqueous solution of 10% hydrochloric acid+10% nitric acid, and then pickled for 2 ~ 5 minutes. ?

The alloy has good electroplating performance, and the surface can be plated with gold, silver, nickel, chromium and other metals. In order to facilitate welding or hot-pressing bonding between parts, copper, nickel, gold and tin are usually plated. In order to improve the conductivity of high frequency current and reduce the contact resistance to ensure normal cathode emission characteristics, gold and silver coatings are often plated. In order to improve the corrosion resistance of the device, nickel plating or gold plating can be used [1 1]. ?

5.5? 4J29 Machining and Grinding Performance The cutting performance of this alloy is similar to that of austenitic stainless steel. High-speed steel or cemented carbide tools are used for machining, and low-speed cutting is adopted. Coolant can be used when cutting. The alloy has good grinding performance.