The mechanical behavior of oxidized low alloyed steel has been studied at temperatures between 700°C and 900°C. Such a work is carried out to obtain information about the damages which occur in the oxide scales developed on steels during hot rolling process. Actually the mechanical behavior is tested with a four point bending apparatus at high temperature under controlled atmosphere. Some information about mechanical damages have been collected during the mechanical loading thanks to recording of the sample acoustic emission. During this study, two procedures have been used which differ in the thermal scheme used to build the oxide scales. The results obviously show that the procedure has a great influence on the mechanical behavior of the oxidized low alloyed steel. For instance a marked decrease of the stress is observed at constant displacement between the 900°C and 800°C tests of one procedure, as the opposite behavior is observed with the other procedure. Different points are considered to explain such results, as the thermal strains which are only present in one of the two procedures, the phase transformations in the metal and in the oxide.