Transmission Electron Microscope Study of Cold-Rolled Hadfield Steels

The structure of the Hadfield steel (1.17% C, 12.48% Mn) subjected to 30% cold-rolling at room temperature has been studied by means of transmission electron microscopy. In the electron micrograph a number of parallel fine bands (50∼100 Å) are found, in addition to stacking faults and ε-martensite plates (called ε′-phase) which were previously observed. From the result of the analysis by selected-area electron diffraction, the fine bands newly found are interpreted as deformation twins formed on the (111) planes of the matrix. The formation of such fine deformation twins is considered to cause work hardening of the Hadfield steel together with the formation of the ε-phase and the stacking faults.