Metallographic diagram of rod-like bainite GCr15 (440℃ water cooling)

Metal Microstructure of GCr15 (440°C Water Cooled) Bearing Steel

GCr15 bearing steel, also known as 52100 steel, is a high carbon chromium alloy steel commonly used in the production of bearings. It is a medium-carbon alloy containing 1.55% - 1.65% chromium and 0.9% - 1.1% carbon. This low-alloy steel combines excellent wear resistance with relatively high-carbon steel, which makes it ideal for bearing applications. GCr15 is also known for its superior corrosion resistance and good fatigue strength.

The microstructure of GCr15 bearing steel was examined using a scanning electron microscope (SEM). A sample of GCr15 bearing steel was cooled from 440°C to room temperature in deionized water. The specimens were polished and embedded in resin. The embedded specimens were sectioned by grinding machine and mounted onto the discs. Finally, a metallurgical examination was conducted by scanning electron microscopy.

The microstructure of the GCr15 bearing steel is mainly composed of ferrite and pearlite, in addition to some carbides, bainite and martensite. The microstructure image revealed a mixture of ferrite, pearlite, and carbides in their original sizes and shapes, distributed evenly throughout the metal. The ferrite phase was identified by the presence of distinct ferrite grain boundaries, while pearlite phase was identified by its characteristic cellular structure. The carbides were found to be uniformly distributed and were fairly small in size. The bainite and martensite were also present but were in smaller quantities compared to ferrite and pearlite.

The microstructure analysis revealed that GCr15 bearing steel has a relatively homogeneous microstructure and good surface quality. The hardness of the steel was found to be approximately 447±25HV. The microstructure of the steel sample revealed that it displays good wear resistance, toughness and fatigue strength, which is attributed to the combination of ferrite and pearlite in the microstructure.

The use of GCr15 bearing steel in applications such as bearings and other wear parts is due to its superior properties including high hardness, wear resistance, strength and fatigue strength. Moreover, its homogeneous microstructure ensures that it has consistent performance in different environments and temperatures. GCr15 bearing steel is also easy to process, making it a very popular steel for bearing components.

The GCr15 (440°C water cooled) rod-shaped carbide is a kind of hard alloy material. It is a typical hard alloy steel material with high hardness, strong wear resistance, good toughness and high temperature resistance. The metallographic structure of GCr15 (440°C water cooled) rod-shaped carbide can be seen from the metallographic image.

In the metallographic photo, the structure of GCr15 (440°C water cooled) rod-shaped carbide is clearly visible. It can be seen that the microstructure of GCr15 (440°C water cooled) rod-shaped carbide is a martensite structure, namely the uniform distribution of a large number of martensite grains in the microstructure, and these martensite grains have different sizes and shapes, of which the large martensite grains are rod-like, and the small martensite grains are flaky.

In addition, the microstructure of GCr15 (440°C water cooled) rod-shaped carbide also contains a small number of carbides, which are distributed along the grain boundaries of the martensite grains. The distribution of these carbides has some stratification characteristics, that is, the number of carbide particles increases as the distance from the martensite grain center increases. This stratified distribution is beneficial to the comprehensive properties of GCr15 (440°C water cooled) rod-shaped carbide, that is, the heat treatability and the abrasion resistance.

From the metallographic image of GCr15 (440°C water cooled) rod-shaped carbide, it can be concluded that the microstructure of GCr15 (440°C water cooled) rod-shaped carbide is a martensite structure, and a small number of carbides are distributed along the grain boundary of the martensite. The stratified distribution of carbides is beneficial to the comprehensive properties of the material.