Overview
Fe-Ni fixed expansion alloys are a series of fixed expansion alloys that can be matched with soft glass and ceramics with different coefficients of expansion in a given temperature range by adjusting the nickel content, and their coefficients of expansion and Curie points increase with the increase of nickel content. The combination of gold is widely used in the electric vacuum industry sealing structure materials. 1.1 4J45 material grade 4J45.
1.1 4J45 material grade 4J45.
1.2 4J45 similar grades See Table 1-1.
1.3 4J45 material technical standards YB/T 5235-1993 "Iron-Nickel-Chromium, Iron-Nickel sealing alloy technical conditions".
1.4 4J45 chemical composition See Table 1-2.
In the average coefficient of linear expansion to the standard conditions, the nickel content is allowed to deviate from the range specified in Table 1-2.
1.5 4J45 heat treatment system The standard coefficient of expansion performance test specimens and its heat treatment system: in a hydrogen atmosphere will be heated to 900 ℃ ± 20 ℃ specimens, holding 1h, not more than 5 ℃ / min rate of cooling to 200 ℃ or less out of the furnace [4].
1.6 4J45 varieties specifications and supply status The varieties are bars, tubes, plates, strips and wires.
1.7 4J45 melting and casting process Melting with non-vacuum induction furnace, vacuum induction furnace or electric arc furnace.
1.8 4J45 Application Overview and Special Requirements 4J45 alloy is mainly used for the production of precision impedance diaphragm, and artificial sapphire, soft glass, ceramic sealing. In the application should make the selected sealing material and the expansion coefficient of the alloy match. Heat treatment should control the grain size to ensure that the material has good deep drawing properties. When the use of forging, rolling material should be strictly check the material air tightness.
Two, 4J45 physical and chemical properties
2.1 4J45 thermal properties
2.1.1 4J45 melting temperature range of the combination of gold melting temperature of about 1430 ℃ [1,2].
2.1.2 4J45 Thermal Conductivity λ=14.7W/(m-°C)[1,2].
2.1.3 4J45 Specific heat capacity The specific heat capacity of this combination of gold are 502J/(kg?°C).
2.1.4 4J45 coefficient of linear expansion The average coefficient of linear expansion of the alloy specified in the standard is shown in Table 2-1. The average coefficient of linear expansion of the alloy is shown in Table 2-2. The expansion curve of the alloy is shown in Fig. 2-2.
2.2 4J45 Density ρ=8.18g/cm3[1,2].
2.3 4J45 electrical properties Resistivity ρ=0.49μΩ-m[1,2].
Three, 4J45 mechanical properties
3.1 Properties specified in the 4J45 technical standards
3.1.1 4J45 hardness Deep-drawn state strips should comply with the provisions of Table 3-1. Strips with a thickness of not more than 0.2mm are not tested for hardness.
3.1.2 4J45 tensile strength The tensile strength of the alloy strip should be in accordance with the provisions of Table 3-2.
3.2 Mechanical properties of 4J45 at room temperature and various temperatures
3.2.1 4J45 hardness The hardness of the alloy (in the annealed state), HV, is about 135[1,2].
3.3 4J45 Endurance and Creep Properties
3.4 4J45 Fatigue Properties?
3.5 4J45 elastic properties?
3.5.1 4J45 modulus of elasticity The modulus of elasticity of this combination of gold E = 158 GPa [1,2].
4.4J45 organization
4.1 4J45 phase transition temperature
4.2 4J45 time-temperature-tissue transition curve?
4.3 4J45 alloy organization The alloy is a stable austenitic organization.
4.4 4J45 grain size The grain size of the deep-drawn strip of the alloy should not be less than 7, and the grain size of less than 7 should 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 strip thickness direction shall be not less than 8.
V. 4J45 process performance and requirements
5.1 4J45 forming properties The alloy is easy to cold and hot working. Hot working temperature should not be too high, the heating time should not be too long, should avoid heating in the sulfur-containing atmosphere. When the cold strain rate of the strip is greater than 75%, annealing will cause plastic anisotropy. Cold strain rate of 10% to 15%, heated to 950 ~ 1050 ℃ (unavoidable in the brazing process) grain growth is significant, resulting in a reduction in the plasticity of the alloy, for the thin section may also lose the vacuum tightness of the metal. Therefore, the final strain rate of the finished product should be controlled at about 60% [2,5].
5.2 4J45 welding performance The combination of gold has good welding performance, can be brazed and spot welding. The combination of gold and soft glass and other materials should be pre-oxidized before sealing.
5.3 4J45 parts heat treatment process Heat treatment can be divided into: stress relief annealing, intermediate annealing and pre-oxidation treatment.
(1) stress relief annealing to eliminate the residual stress of the parts in the machined parts to be stress relief annealing: 430 ~ 540 ℃, insulation 1 ~ 2h, furnace cooling or air cooling.
(2) intermediate annealing in order to eliminate the alloy in the cold rolling, cold drawing, cold stamping process caused by work hardening phenomenon, in order to facilitate the continuation of processing. The workpiece needs to be in a vacuum or protective atmosphere, heated to 700 ~ 800 ℃, insulation 30 ~ 60min, and then furnace cooling, air cooling or water quenching.
(3)Pre-oxidation treatment The combination of gold for sealing material use, in the sealing should be pre-oxidation treatment. Make the alloy surface to generate a layer of uniform thickness, dense oxide film. The parts are heated for 30min in saturated wet hydrogen at 1100°C, and then oxidized in air for 5~10min at about 800°C. The weight gain of the parts is suitable at 0.1~0.3mg/cm2[6].
The combined gold cannot be hardened by heat treatment.
5.4 4J45 surface treatment process Before heat treatment, welding or glass sealing, the metal surface dirt, grease must be removed. Serious oxidized layer can be sandblasted or first soaked in molten lye, and then pickled. Slightly oxidized skin available 25% hydrochloric acid solution at 70 ℃ pickling.
5.5 4J45 cutting and grinding performance The alloy cutting characteristics and austenitic stainless steel is similar. Processing with high-speed steel or carbide tools, low-speed cutting, cutting coolant can be used. Grinding performance is good.