It is a challenge to express it without professional words. Try to explain as follows: Common heat treatment concepts
Heat treatment is one of the important processes in the manufacturing process of mechanical parts. Generally speaking, it can guarantee and improve various properties of the workpiece, such as wear resistance and corrosion resistance. It can also improve the microstructure and stress state of the blank, so as to facilitate various cold and hot processing.
In the process of heat treatment, "four fires" annealing, normalizing, quenching and tempering, among which quenching and tempering are closely related, and they are often used together and are indispensable.
The "Four Fires" evolved heat treatment processes with different heating temperatures and cooling modes.
In order to obtain certain strength and toughness, the process of combining quenching with high temperature tempering is called quenching and tempering.
Some alloys are quenched to form supersaturated solid solutions and kept at room temperature or slightly higher temperature for a long time to improve the hardness, strength or electromagnetic properties of the alloys. This heat treatment process is called aging treatment.
The method of combining pressure working deformation with heat treatment effectively and closely to obtain good strength and toughness of workpiece is called thermomechanical treatment.
Quenching is to heat and insulate the workpiece, and then quickly cool it in quenching media such as water, oil or other inorganic salts, organic water solution, etc. After quenching, steel becomes hard, but at the same time it becomes brittle.
In order to reduce the brittleness of steel parts, the quenched steel parts are kept at an appropriate temperature higher than room temperature but lower than 650℃ for a long time, and then cooled. This process is called tempering.
Normalizing: heating steel or steel parts to a proper temperature higher than the critical point AC3 or ACM for a period of time, and then cooling in the air.
Heat the steel or steel parts above the critical point AC3 or ACM →→→→→→→ and keep them at a proper temperature for a period of time.
→→→→→ cooling in air to obtain pearlite structure.
Annealing:
Heat the sub-divided steel workpiece to 20-40 degrees above AC3 → keep the temperature for a period of time →→ slowly cool with the furnace (or cool in sand or lime) → cool in the air below 500 degrees.
First, the annealing type
1. Complete annealing and isothermal annealing →→→→ Complete annealing is also called recrystallization annealing, generally referred to as annealing. This kind of annealing is mainly used for casting, forging and hot-rolled profiles of various carbon steels and alloy steels with sub-* * composition.
2. Spheroidizing annealing →→→→ Spheroidizing annealing is mainly used for carbon steel and alloy tool steel (such as steel used for manufacturing tools, measuring tools and dies) with the main purpose of reducing hardness and improving machinability. .
3. Stress relief annealing →→→→ Stress relief annealing is also called low temperature annealing (or high temperature tempering).
This kind of annealing is mainly used to eliminate the residual stress of castings, forgings, welded parts, hot rolled parts, cold drawn parts and so on.
PS: Rail is the method and scheme of secondary normalizing cooling, which is even the hot battlefield of rail heat treatment patent at present.