Keywords: heat treatment, concepts, normalisin, annealing, solid solution heat treatment, ageing, solid solution treatment, Ageing treatment, quenching, tempering,

Several common heat treatment concepts

1. normalising: the steel or steel parts heated to the critical point of AC3 or ACM above the appropriate temperature for a certain period of time and then cooled in the air, to get the pearlitic type of organisation of the heat treatment process.

2. annealing: eutectic steel workpiece heated to AC3 above 20-40 degrees, after holding for a period of time, with the furnace slowly cooled (or buried in sand or lime cooling) to 500 degrees below the cooling in the air heat treatment process

3. solid solution heat treatment: the alloy is heated to a high temperature single-phase area at a constant temperature to maintain, so that the excess phase is fully dissolved into the solid solution, and then cooled quickly to get a supersaturated solid solution heat treatment process

4. ageing: after solid solution heat treatment or cold plastic deformation of the alloy, placed at room temperature or slightly above room temperature to maintain the phenomenon of changes in its properties over time.

5. solid solution treatment: so that the alloy in a variety of phases fully dissolved, strengthen the solid solution and improve the toughness and corrosion resistance, eliminate stress and softening, in order to continue to process moulding

6. Ageing treatment: Heating and holding at the temperature where the reinforcing phases precipitate, so that the reinforcing phases precipitate and harden to improve strength.

7. quenching: austenitising steel after cooling at an appropriate cooling rate, so that the workpiece in the cross-section of all or a certain range of unstable organisational structure, such as martensite transformation of the heat treatment process

8. tempering: after quenching the workpiece heated to the critical point of AC1 below the appropriate temperature for a certain period of time, and then cooled in accordance with the requirements of the method, in order to obtain the required organisation and properties of the heat treatment process

9 steel carbonitriding: carbonitriding is to the surface layer of steel at the same time infiltration of carbon and nitrogen process. Customary carbonitriding is also known as cyanide, the current medium-temperature gas carbonitriding and low-temperature gas carbonitriding (i.e. gas nitrocarburising) is more widely used. The main purpose of medium temperature gas carbonitriding is to improve the hardness, wear resistance and fatigue strength of steel. Low-temperature gas carbonitriding to nitriding-based, its main purpose is to improve the wear resistance of steel and bite resistance.

10. Tempering treatment: the general custom will be quenching and high temperature tempering combined heat treatment called tempering treatment. Tempering treatment is widely used in a variety of important structural parts, especially those working under alternating loads of connecting rods, bolts, gears and shafts. Tempered sohnite organisation is obtained after the tempering treatment, and its mechanical properties are better than the normalised sohnite organisation of the same hardness. Its hardness depends on the high temperature tempering temperature and with the steel tempering stability and workpiece cross-section size, generally between HB200-350.

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