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Change the mechanical properties of metals - heat treatment of metals Categories

Article source:China Hardware processing netwResponsible editor:adminauthor:Kangding HardwarePopularity: Publication time:2017-05-11 21:51 font size:【 large middle Small

Change the mechanical properties of metals - heat treatment of metals Categories

Heat treatment process generally includes heating, insulation and cooling process three, sometimes only two heating and cooling processes. The process of convergence with each other, can not be interrupted.

Heating is an important step heat treatment. Metal heat treatment method of heating a lot, the first is the use of charcoal and coal as the heat source, and then use liquid and gaseous fuels. Application of electrical heating is easy to control, and no environmental pollution. With these heat source may be directly heated, it can also be metal or molten salt, as well as the floating particles are heated indirectly.

We all know that after multiple heat treatment process, the specific heat treatment which may be used in it, the following, we outlined several concepts for everyone heat treatment.

1. Normalizing: the heating of steel or steel to a temperature critical point persist for some time after cooling in air.

2. Annealing: the workpiece is heated to 20-40 degrees above the critical point, holding for some time after slow cooling in the furnace or air-cooled oil Ling cooled to below 500 degrees in the air thermal treatment technology.

3. Solution heat treatment: The alloy is heated to a high temperature single-phase region thermostat insist that plenty of excess dissolved into the solid solution phase, followed by rapid cooling to obtain through thermal treatment technology supersaturated solid solution.

4. Aging: workpiece after solution heat treatment or cold plastic deformation at room temperature or slightly above room temperature and place stick, its function changes over time appearance. Time mentioned herein may be hours, it could be a few days Oh, my famous early Dalian Machine Tool Plant, (now seems to obliterate all carry on), because they are important to the body part such as rail, should be placed at the beach for several years to obtain good mechanical properties. Confuse people still think it is putting unused product, in fact, this is an aging process.

5. Disposal solution: each phase in the alloy abundant dissolved standard solid solution strengthening and progress of toughness and corrosion function, to eliminate stress and softening, in order to continue processing molding.

6. Aging disposal: the strengthening phase separation temperature heating and insulation, the reinforcing phase deposition was separated, to be hardening, progressive strength.

7. Quenching: The steel after austenitizing proper cooling rate of the workpiece to be wholly or martensite transformation unstable arrangement layout of thermal treatment technology occur within a certain range in cross-section.

8. Tempering: the hardened workpiece is heated to the appropriate temperature below the critical point must insist on time to meet the requirements of the approach followed by cooling to obtain thermal treatment technology needs arrangements and functions.

9. Carbon and nitrogen permeation steel: carbonitriding is to enter the process of carbon and nitrogen together with the surface layer of steel. Traditionally carbonitriding, also known as cyanide, currently in gas carbonitriding temperature and low-temperature gas carbonitriding (ie gas soft nitriding) more widely used. The primary intent of the temperature gas carbonitriding is progress steel hardness, wear resistance and fatigue strength. In low-temperature gas nitriding carbonitriding mainly, its primary intention is to improve wear resistance of steel and seizure resistance.

10. Quenched disposal: generally accustomed to quenching and tempering heat treatment combination called quenching disposal. Quenched disposal widely used in a variety of important parts of the layout, especially those links in alternating load operations, bolts, gears and shafts, etc. After quenching and tempering sorbite obtained disposal arrangements, its mechanical functions than the same hardness normalizing sorbite is superior arrangement. It depends on the hardness of tempering temperature and tempering stability and workpiece with the cross-sectional dimension of steel, but is usually between HB200-350.

11. Brazing: The solder bonding together two kinds of workpiece thermal treatment technology. This process seems to us the fastener industry is no intersection, I do not know

Metal heat treatment process can be divided into the overall heat treatment, surface heat treatment, local heat treatment and chemical heat treatment. Depending on the heating medium, heating temperature and cooling method, each category can be divided into a number of different heat treatment process. The same kind of metal with different heat treatment process, available in different organizations, so as to have different properties. Steel is the most widely used industrial metal, steel microstructure and also the most complex, and therefore a wide range of steel heat treatment process.

Overall heat treatment is heating the whole piece, and then the appropriate cooling rate, the metal heat treatment process to change its overall mechanical properties. Overall heat treatment of steel roughly annealing, normalizing, quenching and tempering four basic processes.
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