Production, grades and application examples of bake-hardening steel
Bake-hardening steel is first brought into the desired shape by cold forming the steel. It obtains its strength through solid solution hardening by adding manganese, phosphorus and silicon. Carbon, which is dissolved in the lattice, enables this form of steel to achieve a standardised increase in yield strength during heat treatment.
Even painting processes for cars (e.g. 170°C for approx. 20 minutes) can be sufficient to increase the yield strength of bake-hardening steel. This leads to buckling resistance of external components. As the change in mechanical properties (yield strength, elongation at break, n-value) is greatly slowed down and also takes place at room temperature, the shelf life of these steel grades is limited.
The steel is classified according to the VDA 239-100 standard, for example, and is available in various grades. Some of the most common grades are CR180BH, CR210BH, CR240BH, CR270BH. These are dependent on strength and formability.
Bake-hardening steel is used in a variety of applications, especially in the automotive industry, where it is favoured for its hardness and formability. For example, it is used to manufacture car body parts. Other industries also benefit from the properties of the steel. These include the packaging industry, which uses it to produce tins, for example.
