On 2018-08-08 14:48:54
Ten common quenching methods
The manufacturer of high frequency quenching equipment summarizes ten common quenching methods
There are ten commonly used quenching methods in the heat treatment process, which are single medium (water, oil, air) quenching; Double medium quenching; Martensite graded quenching; Martensite graded quenching method below Ms point; Bainite isothermal quenching; Compound quenching; Precooling isothermal quenching; Delayed cooling and quenching; Quenching self - ignition method; Jet quenching, etc.
1, single medium (water, oil, air) quenching
Single medium (water, oil, air) quenching: the quenching of a workpiece heated to a quenching temperature to a quench medium that cools it completely. This is the simplest quenching method and is often used for simple shaped carbon and alloy steel workpieces. Quenching medium according to the part heat transfer coefficient size, hardenability, size, shape, etc.
2, double media quenching
Dual media quenching: the workpiece heated to the quenching temperature is first cooled to close to Ms point in the quenching medium with strong cooling capacity, and then transferred to the slow cooling quenching medium to cool to room temperature, in order to reach different quenching cooling temperature range, and have a better quenching cooling speed. It is used for making large workpiece with complex shape or high carbon steel, alloy steel. Commonly used cooling medium is water-oil, water-nitrate, water-air, oil-air, generally used as fast cooling quenching medium, oil or air as slow cooling quenching medium, less use of air.
3. Martensite grading quenching
Martensitic stage quenching: steel austenitizing, then immersed in the temperature is slightly higher or slightly lower than the steel on the martensitic point of the liquid medium (salt bath or alkali bath), keep the appropriate time, after the steel's inner and outer layers have reached the temperature of the medium out of air cooling, supercooled austenitic slowly into martensitic quenching process. Generally used in the shape of complex and deformation requirements of small workpiece, high speed steel and high alloy steel workers die also used in this way.
4. Martensite grading quenching method below Ms point
Martensite graded quenching method below Ms point: when the temperature of the bath is lower than Ms of the workpiece steel and higher than Mf, the workpiece will be cooled faster in the bath, and the same result can be obtained with graded quenching when the size is larger. It is often used for large steel workpiece with low hardenability.
5. Bainite isothermal quenching
Bainite isothermal quenching: the workpiece is quenched into the bath at the lower bainite temperature of the steel and isothermal, so that the lower bainite transformation occurs. Generally, the workpiece is kept in the bath for 30~60min. CNC WeChat cncdar bainite isothermal quenching process main three steps: (1) austenitizing treatment; (2) cooling treatment after austenitization; (3) bainite isothermal treatment; It is often used for small size parts of alloy steel, high carbon steel and nodular cast iron.
6. Composite quenching method
Composite quenching method: firstly, the workpiece is cooled to below Ms to obtain the martensite with the volume fraction of 10%~30%. Then, the lower bainite area is isothermal to obtain the martensite and bainite structure of the larger section of the workpiece. It is often used in the alloy tool steel workpiece.
7. Pre-cooling isothermal quenching method
Precooling isothermal quenching method: also known as heating isothermal quenching, parts are cooled in the bath with a lower temperature (greater than Ms), and then transferred to the bath with a higher temperature, so that austenite can undergo isothermal transformation. It is suitable for steel parts with poor hardenability or workpiece with large size that must be isothermal quenched.
8. Delayed cooling and quenching method
Delay cooling quenching method: parts in the air, hot water, salt bath pre-cooling to slightly higher temperature than Ar3 or Ar1, and then single media quenching. It is often used for parts with complex shapes with different thickness and small deformation.
9. Quenching self-ignition method
Quenching self - ignition method: will be processed by the workpiece all heating, but in the quenching will only need to be hardened part (often the working part) immersed in quenching liquid cooling, CNC WeChat public cncdar until not immersed in part of the fire color disappeared, immediately out of the air cooling quenching process. Quenching self - ignition method USES the heart not all the cold heat to the surface, so that the surface temper. A shock - bearing tool such as a chisel, punch, hammer, etc.
10. Jet quenching method
Jet quenching: the quenching method of spraying water to the workpiece, the water flow can be large or small, according to the required quenching depth. The jet quenching process does not form a steam film on the surface of the workpiece, so that a deeper layer of hardening can be guaranteed than that quenched in the water. Mainly used for local surface quenching.