Overview of 4J36 expansion alloy The Curie point of 4J36 expansion alloy is about 230 ° C. Below this temperature, the alloy is ferromagnetic and has a very low expansion coefficient. Above this temperature, the alloy is non-magnetic, and the expansion coefficient increases. big.
The alloy is mainly used to manufacture components with approximately constant dimensions in the range of temperature changes, and is widely used in the radio industry, precision instruments, meters and other industries. 4J36 This alloy is a typical low expansion alloy. After long-term use in aviation factories, the performance is stable; the heat treatment process and processing technology should be strictly controlled in use to ensure the stability of the material.
Alloy Magnetic Properties of 4J36 Expanded Alloy:
|
H/(A/m)
|
B/T
|
H/(A/m)
|
B/T
|
|
8
|
1.8×10-2
|
160
|
0.74
|
|
16
|
4.2×10-2
|
400
|
0.97
|
|
24
|
8×10-2
|
800
|
1.12
|
|
40
|
0.2
|
2000
|
1.27
|
|
80
|
0.5
|
4000
|
1.32
|
4J36 parts treatment process The alloy heat treatment can be divided into: stress relief annealing, intermediate annealing and stabilization treatment.
(1) Stress relief annealing In order to eliminate the residual stress of the parts after machining, stress relief annealing should be carried out: 530 ~ 550 ºC, heat preservation for 1 ~ 2h, furnace cooling.
(2) Intermediate annealing is to eliminate the work hardening phenomenon caused by the cold rolling, cold drawing and cold stamping process of the alloy, so as to facilitate continued processing. The workpiece is heated to 830 ~ 880 ºC, kept for 30 minutes, furnace cooling or air cooling.
(3) Stabilization treatment is a treatment that has a lower expansion coefficient and can stabilize its performance. Generally, three-stage processing is used.
a) Homogenization: During heating, the impurities in the alloy are fully dissolved and the alloying elements tend to be uniform. The workpiece is heated to 830 ° C in a protective atmosphere, kept for 20 min to 1 h, and then quenched.
b) Tempering: The stress caused by quenching can be partially eliminated during the tempering process. The workpiece is heated to 315°C, kept for 1 to 4 hours, and cooled in the furnace.
c) Stabilization aging: to stabilize the size of the alloy. The workpiece is heated to 95ºC and kept for 48h.
For high-precision parts after cold working or machining, when high temperature treatment is not suitable, the following stress relief and stabilization treatment can be used: the workpiece is heated to 315 ~ 370 ºC for 1 ~ 4h. This alloy cannot be hardened by heat treatment.
4J36 Surface treatment process: The surface treatment can be sandblasted, polished or pickled.
The alloy can be pickled with 25% hydrochloric acid solution at 70ºC to remove the oxide scale. At 4000A/m, the residual magnetic induction intensity Br=0.6T, and the coercive force Hc=48A/m[1,2].
Nickel: 35-38
Chromium: 0.5
Iron: surplus
Carbon: 0.1
Manganese: 0.06
Silicon: 0.35
Cobalt: 1.0
Molybdenum: 0.5
Phosphorus: 0.02
Sulfur: 0.025
4J36 mechanical properties:
Density: ρ=8.1g/cm3
Melting temperature range: 1430ºC
Curie temperature: 230 ºC
Specific heat: 515J/Kg
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