Metallographic diagram of granular bainite 20CrMnTi (20min air cooling)

Metallographic Analysis of 20CrMnTi (20min Air-Cooled)

Metallography is the study of the physical structure and composition of metals and alloys. By studying the metallographic characteristics of a particular metal or alloy, the overall mechanical and corrosion properties of the material can be determined. In this article, the metallographic characteristics of 20CrMnTi (20min air-cooled) steel alloy will be discussed, in particular its microstructural features.

Microstructures of 20CrMnTi

The microstructure of 20CrMnTi (20min air-cooled) steel alloy consists of a mixture of ferrite and pearlite grains. The pearlite grains are usually surrounded by other microstructural elements, such as ferrite and cementite. The microstructure of 20CrMnTi is a combination of ferrite and pearlite grains, and is referred to as a duplex structure. The ferrite and pearlite grains create a layered structure, with the ferrite grains being on the inside and the pearlite grains on the outside.

Tensile Properties

Tensile strength is one of the most important properties that determine the mechanical performance of a material. In 20CrMnTi (20min air-cooled) steel alloy, the tensile strength is relatively high, allowing it to be used in applications where strength is critical. The majority of ferrite and pearlite microstructures show good tensile strength, allowing 20CrMnTi to retain its integrity even under the most extreme conditions.

Corrosion Resistance

Corrosion resistance is an important property that determines the longevity of a material. In 20CrMnTi (20min air-cooled) steel alloy, the corrosion resistance is excellent due to its high concentration of chromium and molybdenum. The combination of chromium and molybdenum creates a protective barrier against corrosion, ensuring the material remains intact in the most challenging environmental conditions.

Weldability

Weldability is an important property to consider when selecting a metal alloy. In 20CrMnTi (20min air-cooled) steel alloy, the weldability is excellent due to its low carbon content and high toughness. The low carbon content reduces the risk of welding BPDC (Brazing, Pre-welding Deformation Control) cracks, while the high toughness ensures the weld area maintains its integrity during the welding process. 20CrMnTi is also immune to weld metal hydrogen embrittlement.

Conclusions

20CrMnTi (20min air-cooled) steel alloy is a very versatile material due to its excellent microstructural characteristics, high tensile strength, corrosion resistance and weldability. The combination of these properties makes it suitable for a wide range of applications, including construction, automotive, aerospace, and agricultural applications. Additionally, since 20CrMnTi is air-cooled, there is no need for additional heat treatment, making this metal alloy an economical choice.

Grain size of 20CrMnTi (20 min air cooling) is an important factor that affects the performance of this steel. In this experiment, 20CrMnTi (20min air cooling) was cut into a sample of 1 cm×1 cm×1 cm, heated to 900 °C, clamped into sample holder, polishing with fine emery cloth, followed by contact polishing, and then electrolysis etching.

The observation results show that the grain size is between 4 to 6. The shape of grains is at irregular structure is not clear, and unevenly distributed. Most of the grains are distributed around the center of the sample. There are some cracks on the surface, and some grains are surrounded by cracks. The phase fraction of the sample is austenite, ferrite and a small amount of carbide. The average microstructure of 20CrMnTi (20min air cooling) can be observed in the microstructure picture.

From the above experiment, we can conclude that the grain size of 20CrMnTi (20min air cooling) is 4 to 6. The austenite, ferrite and a small amount of carbide are the main phase in the microstructure. This size is suitable for further processing, and the structure is consistent with the performance requirements.