Wed, 18 Jul 2018 02:29:35 +0000
Vacuum heat treatment of special materials
To have difficulty disaster countermeasures to prevent automated process stability as single do not meet the requirements of environmental protection for the operator (short-term training) hills per ha oxygen probe, infrared meter high knowledge base ring An good good bad special alloy easy difficult high hills per ha cheap operating cost low equipment investment from the vacuum heat treatment using a vacuum technology to reduce the partial pressure of oxygen in the atmosphere, it is easier to implement than the controlled atmosphere heat treatment bright heat treatment (impurity content of less than one over one thousand of one percent to controlled atmosphere. In particular, the gas released from the material is timely removed from the furnace, preventing the oxidation reaction on the workpiece surface. Vacuum heat treatment with degreasing, rust on the surface, surface is able to high degree of purification and activation, and easy to realize controllable slowly heating, and rapid cooling, so the vacuum heat treatment deformation is small. Compared with vacuum carburizing, even at a high level of controlled atmosphere carburizing, it is inevitable to have a grain boundary oxidation layer of 10U. Controlled atmosphere requires strict management and control of chemical quantity such as carbon potential, while vacuum heat treatment requires only control of physical quantity such as pressure, easy automation and stable product quality. The vacuum heat treatment can be cooled by nitrogen, argon and other inert gases, which is safe, pollution-free and pollution-free.
As a result of above characteristic, vacuum heat treatment has the advantages of the controlled atmosphere heat treatment is more, and because of good quality, little deformation, energy saving and safety features, such as controlled atmosphere heat treatment in the world since the recent tendency to vacuum heat treatment are on the rise. For many materials, special requirements hills per ha temperature treatment (> 1000 c), low temperature (30075 (TC) and active metal (such as qin), or containing active element (Ti, Nb) higher material, the best choice of the vacuum heat treatment is necessary.
Heat treatment of stainless steel and heat resistant steel 2.1 austenitic non-reinforced stainless steel, heat resistant steel, etc.
Purpose of heat treatment: in order to obtain high corrosion resistance, high plasticity and to eliminate cold hardening and restore plasticity, the treatment should be carried out by panfire (or solid solution).
Process: 105 (TC11501 water, oil and air cooling (depending on the size, effective size and shape of the workpiece).
Application: 0Crl8Ni9 roller eliminates vacuum annealing of cold hardening: 104CTC, lfTPa, oil cooling.
Treatment results: surface bright, plastic recovery, can continue processing.
2.2 martensite can strengthen stainless steel, heat resistant steel lCrl3, 2Crl3, 3Crl3, 4Crl3, 9Crl8, etc. This kind of steel may be subjected to the following different heat treatment according to different USES and technical requirements.
A, to obtain high strength, high corrosion resistance (quenching + tempering at low temperature) B, for strength and elastic hills per ha (temperature quenching + tempering) C, to get good mechanical properties and high corrosion resistance (panxi fire + high tempering) D, hills per ha for removing processing stress, to reduce the hardness, plasticity and toughness (annealing) E, in order to improve the organization for normalizing and high temperature tempering, normalizing + high tempering) F, precipitation hardening stainless steel in order to good mechanical properties and corrosion resistance, can be solid solution plus aging treatment.
25mm, or threaded parts, threaded holes, blind parts and other heat treatment, it is recommended to use a vacuum furnace. The requirement of vacuum furnace, furnace pressure for 9 Pa, pressure rise rate shall be no greater than 0.35 Pa per hour. 2.3 application 2.3.1 precipitation hardening stainless steel vacuum aging 0 crl7ni4cu4nb precipitation hardening stainless steel (PH17-4) has excellent corrosion resistance and mechanical properties. Widely used in aerospace products, such as servo valve housing, action cylinder, etc. Due to the presence of Nb and Cu, the surface is easy to oxidize and change into orchid when aging in air furnace. To ensure the smoothness of the parts with and without oxidation, using the vacuum aging, received good results, keep cutting parts surface of metallic luster, aging process is: 480 to 5801, and vacuum high-speed 2.3.2 and corrosion resistant bearing (9 crl8) for corrosion resistance, abrasion resistance, high precision, small deformation of bearing parts for vacuum oil quenching + tempering at low temperature processing m. 10101070 c oil cooling, 3 high temperature alloy heat treatment of high temperature alloy, according to the different elements in points, Ni, Fe, Co, according to the characteristics of the reinforcement points and solid solution strengthening and ageing strengthening. Take Ni – based aging – hardening alloy as an example.
Model and component solid solution cooling aging cooling air cooling 3.3 requirements for vacuum furnace 3.4 application: metal film box for sealing end face of engine. The thickness of the material for high temperature alloy GH169, S =. 2 nm. Parts after welding to reinforce a solid solution treatment and aging, then do the overload test, pressure 0.2 MPa, maintain 5 minutes, parts shall not be deformation and buckling. Then the second strengthening treatment was carried out, and repeated compression and heating test were conducted for more than 10 times.
Soil 10X: 0.5h insulation for air cooling; After the second strengthening aging, the room temperature strength of 6226MPa (6b 125kgf/mra2h) will be seriously oxidized when heated in a common electric furnace and cooled in air. Therefore, we used vacuum heat treatment for solid solution treatment, and changed air cooling to furnace cooling to room temperature. First aging: 72 (TC, 4h, furnace cooling to room temperature: second aging: 620 C, 16h, furnace cooling to room temperature; The vacuum degree of the parts shall not be lower than 1.33Xl (T3Pa) as the furnace heats up. After the above treatment, the parts shall be silver-white with no deformation. The process test, repeated compression and pressure test of the parts are qualified, and the vacuum heat treatment of high temperature alloy GH169 film box is realized.
13. It makes it clear that these easily oxidized elements in the vacuum quenching furnace oxidize quickly; The hardened oil also gives the parts a different degree of color, so GH169 has a poor color for the surface of the solid solution treatment in this type of furnace.
4 4.1 ingredient brand TC4 titanium alloy heat treatment of the stress relieving 50065 r26h air-cooled general annealing 70080 r12h air-cooled solid solution lh air-cooled aging 500 x 90000.5:26 h 2 recommended process vacuum pressure rise rate of thermal insulation, air cooled before 4.3 requirements for equipment to prevent the oxygen, nitrogen, hydrogen pollution 4.4 application of Ti alloy ageing, made of TC4 spherical accumulator, wall after 3 nun, demand destruction pressure not less than 66 mpa, because of the spherical parts with hole, if oxidation, it is difficult to clean up. After the vacuum heat treatment, not only the surface is very bright, but also the material is purified, giving full play to the properties of the material. The process is 55 (TC, 4h, and vacuum is no less than 1.33 xl2pa.l (r2Pa).
The reason that affects color is that titanium has strong activity and is easy to be oxidized and colored. First equipment factors is very important, need to be aware of is the ultimate vacuum is not more than eight xl4pa, pressure rise rate is not greater than 5 x10lpa/h, after much oven, vacuum furnace, furnace without other pollution sources, it is ok. If the effect is still not satisfied, can from the following eight reasons: (1) before cleaning, (2) artifacts charging gloves, (3) heating vacuum as far as possible, and (4) work before vacuum cannot too tall, elements volatilize, (5) control, temperature and vacuum degree of the change, as far as possible match, 6 note cooling gas composition (Ar, N2), impurities and moisture should be less as far as possible, all landowners melt temperature < 8 (TC, today just replace diffusion pump, such as new oil to obtain the best shining surface is bad.
The vacuum heat treatment of elastic alloys can be divided into Fe, Ni, Co, Ti and Nb groups according to chemical composition. Now specify the iron base alloy, for example, the alloy is dispersion strengthened austenite alloys, the hardening state after solid solution has good plasticity, element shape, can be strengthened after aging, has high mechanical properties and elasticity, non-magnetic, corrosion resistant. The working temperature of 31 can reach 25 (TC, 32 can reach 35 (TC, 353 can reach 400C, these are all high-explosive materials widely used in precision instruments, aerospace and aerospace fields.
5.1 composition of iron-based high elastic alloy thickness (mm) vacuum cooling medium water, oil, gas, oil and water 5.2 recommended process (1) solid solution furnace charging quantity can’t too close, to ensure the uniformity of heating, cooling and vacuum degree 1.33 X 3, for example, many parts in electro-hydraulic servo valve is made of 31, such as feedback pole, the spring rod, nozzle, dampers, etc. These parts have high dimensional accuracy, and the tolerance is sometimes below 0.003mm. Some parts have a diameter of only 0.8mra, with many holes below, and complex shapes. The parts are refined after the solidification, dissolution and quenching of the damaged materials. Because of the unmatched size, they will not be processed any more, so they should not be oxidized after heat treatment.