Common heat treatment processes for cast basalt pipes include normalizing, annealing, solid solution, aging, quenching, tempering, annealing, carburizing, nitriding, quenching and tempering, spheroidizing, brazing, etc.:
- Normalizing: heating steel or steel parts to an appropriate temperature above the critical point AC3 or ACM for a certain period of time and then cooling in air to obtain a heat treatment process of pearlite structure.
- Annealing annealing: heat the hypoeutectoid steel workpiece to 20-40 degrees above AC3, after holding for a period of time, slowly cool with the furnace (or cool in sand or lime) to below 500 degrees and cool in air. craft.
- Solid solution heat treatment: the alloy is heated to a high temperature single-phase region and maintained at a constant temperature, so that the excess phase is fully dissolved into the solid solution, and then rapidly cooled to obtain a supersaturated solid solution.
- Aging: After the alloy is subjected to solution heat treatment or cold plastic deformation, when the thick-walled tube is placed at room temperature or kept slightly higher than the room temperature, its properties change with time.
- Solid solution treatment: fully dissolve various phases in the alloy, strengthen the solid solution, improve toughness and corrosion resistance, eliminate stress and soften, so as to continue processing and forming.
- Aging treatment: Heating and maintaining the temperature at the precipitation temperature of the strengthening phase, so that the strengthening phase is precipitated, hardened, and the strength is improved.
- Quenching: A heat treatment process in which the steel is austenitized and then cooled at an appropriate cooling rate, so that the workpiece can undergo martensite and other unstable microstructure transformations in all or a certain range of the cross section.
- Tempering: The quenched workpiece is heated to an appropriate temperature below the critical point AC1 for a certain period of time, and then cooled by a method that meets the requirements to obtain the required structure and properties.
- Carbonitriding of steel: Carbonitriding is the process of infiltrating carbon and nitrogen into the surface of steel at the same time. Traditionally, carbonitriding, also known as cyanidation, is widely used in medium-temperature gas carbonitriding and low-temperature gas carbonitriding (ie, gas soft 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 is mainly nitriding, and its main purpose is to improve the wear resistance and seizure resistance of steel.
- Quenching and tempering: It is generally customary to combine heat treatment with quenching and high temperature tempering as quenching and tempering. 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 sorbite structure is obtained, and its mechanical properties are better than the 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 size of the workpiece section, generally between HB200-350.
- Brazing: a heat treatment process in which two workpieces are heated, melted and bonded together with brazing filler metal.