S20A (900℃×1 water quenching) metallographic diagram

The microstructure of S20A steel after it has been quenched at 900 degrees Celsius for one hour is composed of pearlite, decahedral spheroidite, Widmanstatten structures, as well as some retained austenite.

The pearlite is the primary phase present in the microstructure, which shows interconnected grains that display a laminate structure. Intergranular boundaries between the pearlite grains appear to have a ‘stair step’ like pattern. This indicates the pearlite has been formed through the basified process. The pearlite structure also shows thin plate-like areas, which indicates the presence of a Widmanstatten structure.

In addition to the pearlite, the microstructure contains a small amount of decahedral spheroidite. Decahedral spheroidite, which is also known as ferrite-cementite, is a very hard and brittle substructure that is known to limit the toughness and ductility of a material. It appears to form from areas of high localized strain or stress, and its presence indicates that the microstructure has undergone significant plastic deformation.

The third phase present in the microstructure is Widmanstatten structures. These are very hard, elongated grains of non-uniform shape that are interspersed among the pearlite. They are created as a result of localized and discontinuous cooling, which causes the iron carbide to form in a disordered, branching pattern. Widmanstatten structures are a significant source of strength and hardness in the microstructure.

Lastly, a small amount of retained austenite is present in the microstructure. Retained austenite is a form of metastable iron-carbon phase, which was not transformed during the quench and is resistant to further transformation. Its presence indicates that the quench temperature was insufficient to transform the austenite to the desired structure.

Overall, the microstructure of S20A steel after it has been quenched at 900 degrees Celsius for one hour contains pearlite, decahedral spheroidite, Widmanstatten structures, as well as some retained austenite. These phases offer the material different qualities such as strength, hardness, toughness, and ductility. The presence of retained austenite indicates that the quench temperature was insufficient to fully transform the austenite.

H1S20A is a type of anthracite carbon steel produced by hot water quenching at 900 ℃. According to metallographic analysis, the H1S20A steel is composed of a low amount of ferrite and a large number of martensite. The martensite is uniform and appears as a four-phase carbide distribution. It is characterized by small carbides and a fine dispersion of a small amount of carbides. The carbides are distributed in a band shape along the grain boundary. The micro hardness is high, which indicates that it has good wear resistance and high hardness.

The shape of H1S20A ferrite is blocky. The size of the ferrite is fine, and the texture is uniform. There are fewer elements in the structure, and the fiber orientation of the ferrite is mainly along the rolling direction. The grain size of the ferrite is mainly in the range of 7-8, and continuous fibrous structure can be seen in cross-section. The matrix of the steel is composed of long-range ferrite grains containing a small amount of inclusions.

The H1S20A steel contains a very small amount of pearlite, which is mainly distributed between the grains of the ferrite. The pearlite is composed of lath-like laminar cementite and nearly anisotropic ferrite. It is a brittle compound that is not conducive to strength and toughness. In addition, there is no Brittleness at room temperature.

In summary, the H1S20A steel has good wear resistance and high hardness with small carbides and fine dispersion. The ferrite is fine with blocky shape and uniform texture, and the grain size of the ferrite is mainly 7-8. The pearlite is mainly distributed between the grains of the ferrite, which is not conducive to its strength and toughness.