1.Normalizing: the heat treatment process of heating steel or steel parts to an appropriate temperature above the critical point AC3 or ACM for a certain time and cooling in the air to obtain the kind of organization as pearlite structure.

2.Annealing: annealing is to heat the workpiece to an appropriate temperature, adopt different holding time according to the material and workpiece size, and then cool it slowly, so as to make the internal structure of the metal reach or close to the equilibrium state, or release the internal stress generated by the previous process and obtain good process  and performance, Or prepare for further quenching.

 That is, the hypoeutectoid steel workpiece is heated to 20-40 degrees above AC3, after holding for a period of time, then it is cooled slowly in the furnace (or buried in sand or lime) to less than 500 degrees and cooled in air.

3.Solution heat treatment: heat the alloy to the high-temperature single-phase zone and keep at a constant temperature, so that the excess phase is fully dissolved in the solid solution, and then cool quickly to obtain the supersaturated solid solution.

4.Aging: after solution heat treatment or cold plastic deformation, when the alloy is placed at or slightly higher than room temperature, its properties change with time.

5.Solution treatment: fully dissolve various phases in the alloy, strengthen the solid solution, improve the toughness and corrosion resistance, eliminate stress and softening, so as to continue processing and forming.

6. Aging treatment: heat and keep warm at the precipitation temperature of the strengthening phase to precipitate the strengthening phase, harden and improve the strength.

7.Quenching: quenching refers to rapid cooling in water, oil or other inorganic salt solution, organic aqueous solution and other quenching media after heating and holding the workpiece. After quenching, the steel becomes hard but brittle at the same time.

That is, the heat treatment process in which the steel is cooled at an appropriate cooling rate after austenitizing, so that the unstable microstructure transformation such as martensite occurs in all or a certain range of the workpiece in the cross section.

8.Tempering: heat the quenched workpiece to an appropriate temperature below the critical point AC1 for a certain time, and then cool it with a satisfactory method to obtain the required microstructure and properties.

9.Carbonitriding of steel: carbonitriding is the process of infiltrating carbon and nitrogen into the surface layer of steel at the same time. Traditionally, carbonitriding is also called cyanidation. Medium temperature gas carbonitriding and low temperature gas carbonitriding (i.e. gas soft nitriding) are 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 is mainly nitriding, and its main purpose is to improve the wear resistance and bite resistance of steel.

10. Quenching and tempering: in general the heat treatment combining quenching and high temperature tempering is called quenching and tempering treatment. Quenching and tempering treatment is widely used in various important structural parts, especially for the connecting rods, bolts, gears and shafts working under alternating load. Tempered sorbite was obtained after quenching and tempering, and its mechanical properties were better than normalized sorbite with the same hardness. Its hardness depends on the temperature of high temperature tempering and is related to the tempering stability of steel and the cross-section size of workpiece, generally between HB200-350.

11.Brazing: a heat treatment process in which two kinds of workpieces are bonded together with solder