Metallographic diagram of 38CrMoAl (gas nitriding after quenching and tempering)

38CrMoAl is an alloy steel used in a variety of applications. It is a type of high-grade chromium-molybdenum alloy. Usually, it is specified for applications that require superior strength and wear resistance.

38CrMoAl has a composition that includes high amounts of chromium and molybdenum, which makes it particularly resistant to corrosion and oxidation. The alloy also contains other elements, including aluminum, carbon, and silicon, which enhance its strength and workability. It is commonly used in the production of mechanical components, such as bearings, gears, and internal components.

Since it has a high strength-to-weight ratio, the 38CrMoAl alloy is appealing to many engineers and machine shops. Manufacturing components out of the material will result in a lightweight, yet strong and durable construction. Additionally, 38CrMoAl is easy to machine, as well as weld and seal. This makes it a great choice for a variety of applications, where strength and durability are essential.

One of the main advantages of 38CrMoAl is its ability to stand up to high temperature and pressure. This makes it ideal for use in the automotive and aerospace industries, as well as the manufacturing of components for medical and healthcare applications.

Due to the complexity of its composition and various desired characteristics, 38CrMoAl requires specialized processing for its optimal performance. This includes gas carburizing, a process of heat treating the alloy with carbon and nitrogen gas to improve its underlying properties. This is also known as gas nitriding, and is usually carried out after the material has been heat-treated.

Gas carburized 38CrMoAl has a higher heat tolerance and far greater strength and wear resistance than unprocessed alloy. It also has a higher impact toughness and fatigue strength. This makes the alloy very efficient and suitable for use in critical applications.

After gas carburizing, the alloy is ground to the desired dimensions and polished to give it the aesthetic value the manufacturer needs. Some additional treatments, such as blacking or passivation, can be applied to further improve its properties. 38CrMoAl has a higher strength-to-weight ratio than many other high-grade alloys and is a popular choice for high-end construction, making it a favorite for engineering and fabrication professionals.

38CrMoAl steel is a low alloy steel developed in the early 1990s. It is a modified version of 38CrMoAIA steel and is used as a structural material for parts with a high and complex stress load, such as aircraft components and turbine blades. It has good forming, heat and oxidation resistance, making it an ideal material for parts with complex stress loads.

In order to improve its full-time performance, 38CrMoAl steel is usually carburized, nitrided, quenched and tempered. 38CrMoAl steel is often used in gas nitriding after carburized and quenched. This treatment results in improved abrasion resistance and wear resistance, as well as increased fatigue strength, making it an excellent choice for heavy-duty industrial components.

The metallographic structure of 38CrMoAl steel after carburizing and nitriding can be divided into five different microstructures: undiffused carbon excess ferrite, undiffused and diffused carbides, diffused ductile iron, nitride band, and initial austenite. The nitrogen content of the steel is higher than that of 38CrMoAIA and this difference can be clearly seen in the microstructure. The nitride band appears as a lightly colored band in the microstructure and is composed of secondary hardening nitrides, mainly Fe2-3N. The nitride band has a refined fine grain and hardness, which helps increase the fatigue strength of the steel.

In summary, 38CrMoAl is a modified version of 38CrMoAIA steel. It has good formability, heat and oxidation resistance, making it an ideal material for parts with complex stress loads. After sufficient carburizing and nitriding, the microstructure of 38CrMoAl steel is mainly composed of undiffused carbon excess ferrite, undiffused and diffused carbides, diffused ductile iron, nitride band, and initial austenite. The nitride band improves the fatigue strength of the steel, making it better suited for heavy-duty industrial parts.