In this study the microstructural changes in manganese austenitic steel with 9 and 13% Mn in presence of chromium with (1,4-2,0%) was evaluated, thermal cycles of quenching and tempering in order to evaluate the influence of kinetic of cooling on the stability of the phase austenite and the presence of composed of second phase like iron and chromium carbides of type (Fe, Mn)3C and (Fe, Cr)7C3. were also evaluated. The temperature of austenitizing was of 1050 °C, with a time of support of 1 hour and means of cooling water. The tempering treatments took place in a rank of 200 to 800 °C with intervals of 200 °C and dwell time 2 hours. The material was evaluated by electronic microscopy of sweeping (SEM-EDS), spectrometry of optical emission and X-ray diffraction, in state as cast and heat treating.