The main contents of the heat treatment process for products are as follows:

Normalizing of fastener products: A heat treatment process in which steel or steel parts are heated to an appropriate temperature above the critical point AC3 or ACM, held for a certain period of time, and then cooled in the air to obtain a pearlite-like structure.

2. Brazing of fastener products: A heat treatment process in which two workpieces are bonded together with brazing filler metal.

3. Quenching of fastener products: A heat treatment process in which steel is austenitized and then cooled at an appropriate rate to cause a transformation of unstable microstructure such as martensite throughout or within a certain range of the cross-section of the workpiece.

4. annealing of fastener products: A heat treatment process in which hypoeutectoid steel workpieces are heated to 20-40 degrees above AC3, held at that temperature for a period of time, then slowly cooled in the furnace (or buried in sand or lime for cooling) to below 500 degrees and cooled in the air.

5. Aging of fastener products: The phenomenon where the performance of an alloy changes over time when it is placed at room temperature or held slightly above room temperature after solution heat treatment or cold plastic deformation.

6. Solution treatment of fastener products: Fully dissolve various phases in the alloy, strengthen the solid solution, improve toughness and corrosion resistance, eliminate stress and soften, so as to facilitate further processing and shaping.

7. Aging treatment of fastener products: Heat and hold at the temperature where the strengthening phase precipitates, allowing the strengthening phase to precipitate and harden, thereby enhancing strength.

8. Tempering of fastener products: A heat treatment process in which quenched workpieces are heated to an appropriate temperature below the critical point AC1 and held for a certain period of time, and then cooled by a method that meets the requirements to obtain the desired microstructure and properties.

9. Carbo-nitriding of steel for fastener products: Carbo-nitriding is a process in which carbon and nitrogen are simultaneously infiltrated into the surface layer of steel. Conventionally, carbonitriding is also known as cyanidation. Currently, low-temperature gas carbonitriding and medium-temperature gas carbonitriding are widely applied. Low-temperature gas carbonitriding mainly involves nitriding, and its primary purpose is to enhance the wear resistance and anti-seizing property of steel. The main purpose of medium-temperature gas carbonitriding in the national standard for reference screws is to enhance the hardness, wear resistance and fatigue strength of steel.

10. Quenching and tempering treatment of fastener products: Generally, the heat treatment that combines quenching with high-temperature tempering is called quenching and tempering treatment. Quenching and tempering treatment is widely applied to various important structural parts, especially those connecting rods, bolts, gears and shafts that operate under alternating loads. After quenching and tempering treatment, tempered sorbite structure is obtained, and its mechanical properties are all superior to those of normalized sorbite 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 ranging from HB200 to 350.

11. Solution heat treatment of fastener products: A heat treatment process in which the alloy is heated to a high-temperature single-phase zone and held at a constant temperature to allow the excess phase to fully dissolve into the solid solution, followed by rapid cooling to obtain a supersaturated solid solution.