Thermomechanical Processing by Laser in Multiphase Steels

The investigations deal with processes leading to local strengthening effects in multiphase steels. These are characterized by good formability, high strength, and bake hardening (BH) effect. Dual phase (DP) and complex phase (CP) steels have been investigated to examine the effect of thermomechanical processing parameters on local BH ability. For this purpose, local heat treatment by Nd:YAG laser were studied, as well as ageing stability of the adjusted strength. The local heat treatment leads to a local strengthening of the material. The stability of the local effect could be confirmed. Partial heat treatment of multiphase steels by laser seems to open a new field of application for the local use of the BH effect. Potential is given to influence relevant areas only, thus representing a method for energy-saving.