Effects of DP steel microstructure on the disappearance of discontinuous yielding

Abstract

Although in terms of quality is not as high as TRIP steel, DP steel has been developed as an option to meet the minimum standard industrial requirement for automotive. Steel development for automotive material leads to posses high strength without suffering its ductility and weld ability, in addition there is no appearance of discontinuous yielding that cause stretcher strain marking. The change of micro structure as a result of the intercritical annealing process not only increases the strength of Dual Phase Steel, but also eliminates the discontinuous yielding. The phenomenon of discontinuous yielding is no longer appear in Dual Phase Steel which heating time on intercritical annealing process more than 1 minute, the minimum time is equal to the disappearance of discontinuous yielding. The phenomenon of upper yield point and discontinuous yielding on carbon steel is strongly influenced by the magnitude of the stress acting on the Ferrite phase to move the dislocation of the pinned state by the interstitial atom. From the recent works gives the result that the disappearance of discontinuous yielding in Dual Phase Steel resulting from the intercritical annealing process makes Dual Phase Steel very suitable as an automotive material.