A DYNAMIC OBSERVATION OF MICROSCOPIC DEFORMATION BEHAVIOR IN DUAL-PHASE STEELS

Microscopic deformation behavior in some dual-phase steels consisting of ferrite and martensite has been observed continuously by using a scanning electron microscope with tension stand, and the strain values of two phases have been measured with graphanalyse technique. The results show that the distribution of strain between two phase and that in each phase are so nonuniform as to cause a strain gradient in front of martensite islands. The ratio of strain in martensite to that in ferrite increases with the increase of martensite content and tempering temperature as well as the decrease of carbon content in marteniste. The yield strength of dual phase steel with ferrite matrix is controlled by the ferrite.