Identification of Steels by Colors

Classification of steels by colors is a method used to determine the properties of heat-treated steels. This method is based on the naming of steels according to their colors, relying on the color of the oxide layer formed on the steel surface during the hardening process.

This method is commonly used in controlled-temperature hardening processes, typically applied after the production or processing of steels. Color classification is used for applying different hardening processes to achieve various steel properties.

In this method, the color of the oxide layer formed on the steel surface during hardening is considered an indicator of the temperature the steel was exposed to during the hardening process. Generally, as the temperature increases, the color of the oxide layer formed on the steel surface changes. Colors are generally classified as cold colors, warm colors, and bright colors.

Cold colors typically indicate that the steel was hardened at lower temperatures, forming a thin oxide layer on its surface. Blue and green colors commonly fall into this category.

Warm colors indicate that the steel was hardened at higher temperatures, forming a thicker oxide layer. Yellow, brown, and red colors are examples in this category.

Bright colors indicate a very thin oxide layer on the steel surface. These colors are often bright yellow, silver, or gray.

This color classification assists in determining the appropriate temperature range for the hardening process of steels and helps achieve the desired hardness, strength, and other mechanical properties.