Hardened steel is a type of steel that has been treated to increase its strength and durability. It is widely used in various industries, including construction, automotive, and aerospace. The essential constituent of hardened steel is martensite.

Martensite

Martensite is a crystalline structure that forms in steel when it is rapidly cooled from a high temperature. It is a very hard and brittle phase of steel, and is responsible for the increased strength and hardness of hardened steel.

Formation of Martensite

Martensite forms when steel is heated to a high temperature, typically above 900°C, and then rapidly cooled by quenching it in a liquid such as water or oil. This rapid cooling prevents the steel from forming its usual crystal structure, and instead causes the atoms to rearrange themselves into a highly ordered, crystalline structure known as martensite.

Properties of Martensite

Martensite is a very hard and brittle phase of steel, with a high tensile strength and hardness. It is also highly resistant to wear and abrasion, making it ideal for use in applications where durability is important. However, it is also very brittle and can crack or fracture under stress, making it unsuitable for certain applications.

Conclusion

In conclusion, the essential constituent of hardened steel is martensite, which forms when steel is rapidly cooled from a high temperature. Martensite is responsible for the increased strength and hardness of hardened steel, and is highly resistant to wear and abrasion. However, it is also very brittle and can crack or fracture under stress.