18Cr2Ni4WA (quenching and tempering after carburizing) metallographic diagram

Cr18Cr2Ni4WA(Carburized and Hardened) Microstructure

Steel is a very versatile material that is used for a vast range of purposes. Cr18Cr2Ni4WA (Carburized and Hardened) is one of the more robust steels that can be used in a range of applications, such as automotive and architectural components. In this study, the microstructure of Cr18Cr2Ni4WA (Carburized and Hardened) is investigated to understand its properties and behavior.

Microstructure

Generally, the microstructure of Cr18Cr2Ni4WA (Carburized and Hardened) includes three layers. The outer layer is the carburized layer, a layer of high hardness and wear resistance due to the incorporation of carbon. This layer is typically composed of martensite with a few carbides. The inner layer is a transition layer, typically composed of ferrite with a few carbides, which provides the steel with toughness. The center layer is the core which is composed mostly of ferrite.

Treatment

The microstructure of Cr18Cr2Ni4WA (Carburized and Hardened) is formed after the following treatment:

1. Carburizing: This is the main process of hardening the steel. A carbon rich atmosphere is applied to the surface of the steel, resulting in an increased concentration of carbon atoms in the outer layer.

2. Quenching: Quenching increases the hardness of the steel by cooling the steel to a low temperature rapidly. This causes rapid recrystallization, resulting in a hard and wear-resistant structure.

3. Tempering: Tempering is used to reduce the hardness of the steel by heating it to a temperature below the quenching temperature. This causes microstructural changes, resulting in a decrease in hardness.

4. Reheating: Reheating is used to restore the hardness and strength of the steel after tempering.

Conclusion

In conclusion, the microstructure of Cr18Cr2Ni4WA (Carburized and Hardened) consists of three distinct layers. The outer layer is composed of martensite and a few carbides, the transition layer is composed of ferrite with some carbides, and the core layer is composed mainly of ferrite. The microstructure is formed after the steel has been carburized, quenched, tempered and reheated. The combination of these processes results in a steel with a high hardness, wear resistance and toughness.

The 18Cr2Ni4WA steel is a low carbon, low alloy steel which has been carburized and then quenched and tempered to enhance its physical and mechanical properties. This steel is widely used in the production of components in a wide range of industries such as automotive bearing components, valves and pumps.

The 18Cr2Ni4WA steel composition is 0.17~0.21% carbon, 0.4~0.7% chromium, 1.3~1.8% nickel, 0.25~0.35% molybdenum and balance iron. The process of carburizing incorporates carbon into parts of the steel to enhance wear and fatigue resistance. The carburizing also has the potential benefit of lowering ductility values of the steel, as long as large amounts of retained austenite are avoided.

18Cr2Ni4WA steel structure mainly consists of martensite or tempered martensite. Sometimes, inclusions of retained austenite and carbides are found in the structure. The polishing microstructure reveal a uniform carbon distribution across the microstructure. The eutectoid transformation of carbon-rich austenite to pearlite occurs near the surface of the steel, with a carbon gradient moving deep into the steel.

In summary, 18Cr2Ni4WA is a low carbon, low alloy steel with a carburized, quenched and tempered process. The steel structure contains martensite and tempered martensite, with some inclusions of retained austenite and carbides. Its polishing microstructure show a uniform carbon distribution across the microstructure with a carbon gradient. This steel is widely used for automotive components and other industrial equipment that requires strong and wear resistant properties.