Too comprehensive! A list of ten typical quenching procedures!
A list of ten common quenching procedures.
In the heat treatment process, there are ten commonly used quenching methods: single medium (water, oil, air) quenching; dual medium quenching; martensite graded quenching; martensite graded quenching method below the Ms point; bainite isothermal quenching method; compound quenching method; precooling isothermal quenching method; delayed cooling quenching method; quenching self-tempering method; spray quenching method, etc.
1. Quenching in a single medium (water, oil, or air)
Quenching in a single medium (water, oil, or air): A workpiece that has been heated to the quenching temperature is quenched into a quenching media to totally cool it. This is the most basic way of quenching and is commonly used for carbon steel and alloy steel workpieces with simple forms. The quenching media is chosen based on the heat transfer coefficient, hardenability, size, form, and other properties of the part.
2. Medium quenching twice
Dual-medium quenching: To reach different quenching cooling temperature ranges and have a relatively ideal quenching cooling rate, the workpiece heated to the quenching temperature is first cooled to close to the Ms point in a quenching medium with strong cooling capacity, and then transferred to a slow-cooling quenching medium to cool to room temperature. This process is frequently used for complex-shaped parts or large workpieces manufactured of high-carbon steel and alloy steel. Carbon tool steels are also frequently employed. Water-oil, water-nitrate, water-air, and oil-air are all common cooling mediums. Water is commonly utilized as a rapid cooling quenching media, whereas oil or air is employed as a delayed cooling quenching medium. Air is hardly used.
3. Martensite quenching graded
Martensitic graded quenching: the steel is austenitized, then immersed in a liquid medium (salt bath or alkali bath) at a temperature slightly higher or slightly lower than the steel's upper Martensite point, and held there for an appropriate time until the inner and outer surfaces of the steel parts are smooth. When the layers reach a medium temperature, they are removed for air cooling, and the supercooled austenite gradually transforms into martensite during the quenching process. It is typically applied to small workpieces with complex forms and stringent deformation constraints. This process is also often used for quenching tools and molds made of high-speed steel and high-alloy steel.
4. Martensite graded quenching method at Ms point or lower
Below Ms point, the Martensite graded quenching process is used: When the bath temperature is lower than Ms of the workpiece steel and higher than Mf, the workpiece cools faster in the bath, and when the size is bigger, the same effects as graded quenching may still be attained. Larger steel workpieces with low hardenability are frequently employed.
5. Method of Bainite Isothermal Quenching
Bainite isothermal quenching method: The workpiece is quenched in a bath with a lower bainite temperature of the steel and isothermal, allowing the lower bainite transformation to take place, and is typically held in the bath for 30 to 60 minutes. There are three major processes in the bainite austempering process: 1 austenitizing treatment; 2 post-austenitizing cooling treatment; 3 bainite isothermal treatment; widely utilized in alloy steel, high carbon steel small parts, and ductile iron castings.
6. Compound quenching technique
Compound quenching method: for larger cross-section workpieces, first quench the workpiece to below Ms to obtain martensite with a volume fraction of 10% to 30%, and then isotherm in the lower bainite zone to obtain martensite and bainite structures. Alloy tool steel workpieces are often used.
7. Isothermal quenching and precooling
Pre-cooling isothermal quenching method: also known as heating isothermal quenching, the parts are cooled in a lower temperature bath (more than Ms) before being moved to a higher temperature bath to cause the austenite to undergo isothermal transition. It is appropriate for hardenable steel parts or large workpieces that must be austempered.
8. Cooling and quenching procedure with a delay
The pieces are pre-cooled in air, hot water, or a salt bath to a temperature slightly higher than Ar3 or Ar1, and then single-medium quenching is conducted. It is frequently used for items with complex forms and significantly varied thicknesses in many regions that require minor deformation.
9. Self-tempering and quenching method
The entire workpiece to be processed is heated, but just the component that has to be hardened (typically the working part) is immersed in the quenching liquid and cooled during quenching. When the unimmersed part's fire color fades, instantly release it into the air. Quenching procedure with medium cooling. To temper the surface, the quenching and self-tempering process transfers heat from the core that has not entirely cooled to the surface. Chisels, punches, hammers, and other impact-resistant tools are often utilized.
Spray quenching technique 10
Spray quenching method: A method of quenching in which water is sprayed onto the workpiece. Depending on the needed quenching depth, the water flow might be big or little. Spray quenching does not leave a steam film on the workpiece's surface, resulting in a deeper hardened layer than water quenching. It is mostly used for local surface quenching.
