Press hardening


Hot stamping is a relatively new technology which allows ultra-high strength steels to be formed into complex shapes, which is not possible with regular cold stamping operations.

Methods

1) Indirect Process: the blank is formed, trimmed, and pierced in cold condition. It is later heated and quenched in a die to get high strength properties.
2) Direct Process: the unformed blank is heated in a furnace, formed in hot condition, and quenched in the die to achieve the required properties.
Selection of the process depends on part complexity and blank coating. In either method, the blank is formed in a much softer and formable state and is later hardened in the dies, which have drilled cooling channels. A typical hot stamped components has 1000 MPa Yield Stress and 1500 MPa Ultimate tensile strength.

Advantages

Higher strength steels may help reducing the weight by downgaging, while increasing the crashworthiness. However, one problem with many high strength steels is that their formability is generally lower than milder grades. In addition, springback and die wear also cause problems as the forming stresses and contact pressures are higher.