Single and dual phase steels for car body outer panels produced by bake-hardening
For car body outer panels it is necessary to have steels with good formability. It is possible to use steels with low yield on press forming, capable of developing high strength on the panel due to a high work-hardening rate or carbon aging during paint-baking treatment. The purpose of the research was to study the properties that can be obtained with dual phase or single phase steels suitable for bake-hardening. Regarding the dual-phase steels it was found that it is necessary to alloy with more than 1% Mn and it is preferable to adopt a quenching rate that is not too drastic. The use of Mn alone tends to keep the fabrication process very critical, so alloying with moderate amounts of Cr or Mo would seem advisable. In the case of the single-phase steels, it has been confirmed that the continuous annealing process enables very good bake-hardening values to be obtained. It has been found that overaging at 400 C has to be adopted and it is preferable to have slow final cooling (in air) after overaging. In parallel with the experimentation, a mathematical model has been developed of nucleation and growth of second-phase particles (Fe(3)C) during continuous annealing.
Bibliographic Reference: EUR 12037 IT (1989) MF, 102 pp., ECU 8, blow-up copy ECU 13.75
Record Number: 198910351 / Last updated on: 1994-12-01
Original language: it
Available languages: it