refers to a metal hot working process in which materials are heated, insulated and cooled to obtain desired structure and properties in a solid state.
Heat treatment
1. Normalizing:
Heat treatment of pearlitic structures by heating steel to a critical point, AC3 or an appropriate temperature and cooling it after a certain period of time.
2. Annealing:
A heat treatment process for cooling in air. Heat the workpiece of hypoeutectoid steel to 20 -- 40 degrees above AC3. After a period of heat preservation, cool slowly (or be buried in sand or lime) to less than 500 degrees
3. Solid solution heat treatment:
The alloys are heated to a high temperature single-phase zone at constant temperature, allowing the excess phase to be fully dissolved into the solid solution, which is then rapidly cooled to get a supersaturated solid solution.
4. Aging:
The properties of alloys change with time when they are placed at room temperature or slightly above room temperature after solid solution heat treatment or cold plastic deformation.
5. Solid solution treatment:
To dissolve all components in the alloy, strengthen the solid solution, improve toughness and corrosion resistance, eliminate stress and soften, so as to continue processing and molding.
6. Aging treatment:
Raise the temperature, enable the enhanced phase precipitation to precipitate, can harden, improve the intensity.
7. Quenching:
The austenite of steel is cooled at an appropriate cooling rate, so that the workpiece is transformed into martensite in the cross section or within a certain range.
8. Tempering:
The hardened workpiece is heated to an appropriate temperature below the critical point AC1 for a certain period of time, which is then cooled by a method that meets the requirements to obtain the desired microstructure and properties.
9. Carburization of steel
Carburization is a process of simultaneous infiltration of carbon and nitrogen to the surface of steel. Traditionally, carbonitriding is also called cyanation. Carbonitriding of medium temperature gas and low temperature gas is widely used. The main purpose of carbon nitriding is to improve the hardness, wear resistance and fatigue strength of steel. Low temperature gas carbonitriding mainly nitriding. Its main purpose is to improve the wear resistance and anti-bite of steel.
10. Quenching and tempering
The heat treatment combined with quenching and tempering is commonly used to be called quenching and tempering. It is widely used in all kinds of important structural parts, especially the linkages, bolts, gears and shafts which work under alternating loads. The mechanical properties of tempering sorbite are better than that of normalizing sorbite with the same hardness. Its hardness depends on the tempering temperature and is related to the tempering stability of steel and the sectional dimension of workpiece, generally between HB200 and 350.