Metallographic diagram of 45 steel (quenched at 860°C)

Metallographic analysis of 45 steel treated by quenching at 860°C

The metallographic analysis of 45 steel treated by quenching at 860°C was conducted to study the microstructure and mechanical properties of the steel. 45 steel is a low alloy steel composed primarily of iron and carbon. Alloying elements such as manganese, silicon, and chromium may also be present in the steel, although in lower concentrations. Quenching involves rapidly cooling the steel in water or oil to obtain a desired microstructure or mechanical properties from the steel.

The metallographic analysis was conducted on a test specimen that was quenched at 860°C for 10 minutes. A scanning electron microscope (SEM) was used to study the microstructure of the steel in the quenched condition. The results of the SEM analysis revealed that the microstructure of the quenched steel was composed of ferrite, pearlite, and martensite. Ferrite is a form of iron that is soft and ductile and has low strength and hardness. Pearlite is composed of ferrite and cementite, and is considered to be an intermediate microstructure between ferrite and martensite. Martensite is composed entirely of iron and carbon and is extremely hard and brittle, providing the steel with an enhanced strength and hardness.

Hardness tests were conducted on the quenched specimen and the results revealed that the hardness of the steel was enhanced due to the presence of martensite in the microstructure after quenching. The hardness of the steel was measured in several orientations and the results indicate that the hardness in the direction parallel to the quenched plane was significantly higher than that in the direction perpendicular to the quenched plane. This result is attributed to the fact that martensite that is formed in the quenched plane is able to transform more efficiently than martensite in other orientations, resulting in higher hardness in the quenched plane.

Tensile tests were conducted on the quenched specimen and the results revealed that the tensile strength and yield strength of the steel were significantly enhanced due to the presence of martensite in the microstructure after quenching. The tensile strength and yield strength of the steel in the quenched plane direction were found to be increased by up to 28% and 20% respectively, compared to the values prior to quenching. The significant increase in strength and hardness of the steel in the quenched plane direction is attributed to the formation of martensite at the quench plane.

In conclusion, the metallographic analysis of 45 steel treated by quenching at 860°C revealed that the microstructure of the quenched steel was composed of ferrite, pearlite, and martensite. The hardness, tensile strength, and yield strength of the steel were all significantly increased due to the presence of martensite in the microstructure after quenching.

Steel 45 (860°C Quenched) is a kind of high-strength steel which is widely used in the field of heavy mechanical engineering. It is a kind of medium carbon steel with a carbon content up to 0.45%. It has a fairly high strength, good ductility and excellent toughness and is suitable for applications requiring high strength and wear resistance.

It has good hardenability and can be hardened to HRC48-52. It can also reach HRC53 with an austempering process. Steel 45 has excellent impact toughness, good formability and weldability, and can be easily machined by cutting tools.

In metallography, the microstructure of steel 45 (860℃ quenched) can be observed from the polished sample. On the surface of the sample, there is a mixture of ferritic and pearlite structures, and then the microstructure gradually changes from the center to the edge. The ferrite existing in the microstructure of Steel 45 has small grains, showing a fibrous shape. The pearlite grains are dense and uniform, essentially a lamellar structure. The hardness of steel 45 after quenching at 860°C is up to HRC48-52.

In summary, Steel 45 (860°C Quenched) is a kind of high-strength steel with a carbon content up to 0.45% which has excellent impact toughness and formability and is suitable for applications requiring high strength and wear resistance. The metallography reveals the microstructure of Steel 45 which is composed of ferrite and pearlite. Its ultimate hardness reaches HRC48-52 after quenching at 860°C.