38CrMoAl (1100℃×20min+470℃×3s water cooling) metallographic diagram

The microstructure of 38CrMoAl steel after heat treatment is mainly composed of tempered sorbite, lamellar pearlite and a small amount of bainite and martensite. After heat treatment, the hardness of 38CrMoAl steel is HRC34-40, which is an important reason for its good comprehensive properties. The microstructure and hardness of the 38CrMoAl steel after heat treatment can be discuss in details as follows:

1.Tempered sorbite: After heat treatment, the strongest structure of 38CrMoAl steel is tempered sorbite, which include the tempered sorbite structure of ferrite + cementite and ferrite + carbide. The presence of tempered sorbite structure make the 38crmoal steel have higher strength, good machinability and weldability.

2.Lamellar pearlite: Heat treatment can make 38CrMoAl steel has moderate strength, plasticity and toughness、 -In order to enhance the toughness of the steel, lamellar pearlite is existed in 38CrMoAl steel. And in the heat-treated 34CrMo4 steel, these lamellar pearlite have been refined, which has a great effect on improving the ductility of the matrix.

3.A small amount of bainite and martensite: In order to achieve higher strength, the 38crmoal steel has a small amount of bainite and martensite in the heat-treated steel. The bainite and martensite structure has high tensile strength and hardness, which can improve the strength of the 38crmoal steel.

After heat treatment, the microstructure of 38CrMoAl steel is mainly composed of tempered sorbite, lamellar pearlite, a small amount of bainite and martensite. The microstructure and hardness of 38CrMoAl steel can be improved through this heat treatment, which makes the 38CrMoAl steel with good comprehensive properties.

Metallographic analysis of 38CrMoAl (1100℃×20min+470℃×3s water cooling

38CrMoAl is a high strength and high temperature alloy with excellent performance, and its metallographic analysis is of great significance to the further application of alloy. To observe the microstructure of the alloy materials, the metallographic sample of the alloy was prepared by grinding and polished, and then the metallographic analytical was taken using color optical microscopy.

The obtained microstructure consists of a large number of polygonal ferrite grains (white grains) and a small amount of polygonal Widmanstatten ferrite grains (gray grains) evenly distributed in the matrix. The grain size is mostly between 6-7, and the size is mainly small and even, which distributes evenly. The Widmanstatten ferrite has a good intergranular connection, which does not significantly affect the smoothness of the grain boundary surface.

Moreover, this alloy contains a variety of secondary phases such as upper bainite, martensite and so on. Among them, alloy bainite mainly distributes in the grain boundary, and its form is mainly lath-like and rod-like; and some combine with the cementite to form a dispersed lath and rod structure. The martensite contained in this alloy also dispersed in matrix, and its form is mainly lath-like.

In conclusion, through the metallographic analysis, it can be found that the microstructure of 38CrMoAl (1100℃×20min+470℃×3s water cooling) is mainly composed of polygonal ferrite grains and Widmanstatten ferrite grains, and a variety of secondary phases such as upper bainite and martensite also exist, showing good performance.