1. Normalization: The heat treatment process of heating steel or steel parts to a critical point Ac3 (for hypoeutectoid steel) or Accm (for hypereutectoid steel) above 30 ℃ -50 ℃, holding for an appropriate period of time, and uniformly cooling in free flowing air is called normalization
The microstructure after normalizing: hypoeutectoid steel is F+S, eutectoid steel is S, and hypereutectoid steel is S+Fe3CII. The main difference between normalizing and complete annealing is that the cooling rate is faster, with the aim of normalizing the steel structure, also known as normalizing treatment.
2. Annealing: A heat treatment process in which the hypoeutectoid steel workpiece is heated to 20-40 degrees above AC3, held for a period of time, and then slowly cooled in the furnace (or buried in sand or lime) to below 500 degrees and cooled in air
3. Solid solution heat treatment: Heating the alloy to a high temperature single-phase zone and maintaining a constant temperature to fully dissolve the excess phase into the solid solution, then rapidly cooling to obtain a supersaturated solid solution
4. Aging: The phenomenon in which the properties of an alloy change over time when it is placed at room temperature or slightly above room temperature after solution heat treatment or cold plastic deformation.
5. Solid solution treatment: fully dissolve various phases in the alloy, strengthen the solid solution, improve toughness and corrosion resistance, eliminate stress and softening, so as to continue processing and forming
6. Time treatment: Heating and holding at the temperature where the strengthening phase precipitates, allowing the strengthening phase to precipitate and harden, thereby improving strength
7. Quenching: A heat treatment process that austenitizes steel and cools it at an appropriate cooling rate, causing the workpiece to undergo unstable structural transformations such as martensite in all or a certain range of the cross-section
8. Tempering: A heat treatment process that heats quenched workpieces to an appropriate temperature below the critical point AC1 and maintains it for a certain period of time, followed by cooling using a method that meets the requirements to obtain the desired structure and properties
9. Carbonitriding of steel: Carbonitriding is the process of simultaneously infiltrating carbon and nitrogen into the surface of steel. Traditionally, carbonitriding, also known as cyanide, is widely used in medium temperature gas carbonitriding and low-temperature gas carbonitriding (i.e. gas nitriding). The main purpose of medium temperature gas carbonitriding is to improve the hardness, wear resistance, and fatigue strength of steel. Low temperature gas carbonitriding mainly involves nitriding, with the main purpose of improving the wear resistance and bite resistance of steel.
10. Quenching and tempering treatment: It is generally customary to combine quenching with high-temperature tempering for heat treatment, which is called quenching and tempering treatment. Quenching and tempering treatment is widely used in various important structural parts, especially those connecting rods, bolts, gears, and shafts that work under alternating loads. After quenching and tempering treatment, the tempered martensite structure is obtained, and its mechanical properties are superior to those of the normalized martensite structure with the same hardness. Its hardness depends on the high-temperature tempering temperature and is related to the tempering stability of the steel and the cross-sectional size of the workpiece, generally between HB200-350.
11. Brazing: A heat treatment process in which two types of workpieces are bonded together using brazing material
