The microstructure evolution and room temperature deformation behavior of ferrite-based lightweight steel

The microstructure evolution and room temperature deformation behavior of a duplex advanced ferrite-based lightweight steel was investigated through compression testing method. In order to trace the microstructure evolution, the tests were interrupted at the true strains of 0.05, 0.1, 0.15, 0.3 and 0.6. The occurrence of deformation bands in ferrite phase is characterized as the main feature of the developed microstructure under the specified regime and the frequency of deformation bands increases by increasing the imposed strain. To well assess the nature of these deformation bands, electron back scattered diffraction analysis is employed. The results approve that deformation bands are in twin relation with the ferrite matrix. The twins are characterized in conventional {112}[111] system with 60° misorientation and present three point coincidence type pole figures. The ferrite twins are formed in a specific orientation relationship with its mother ferrite orientation thereby strongly affect the strain distribution pattern. The twinning occurrence in ferrite matrix is believed to be as the influencing factor of the observed load fluctuations at the early stage of deformation and at relatively high stress level.