Atrito interno em aços inoxidáveis austeníticos contendo cobre

The influence of the different types and amounts of strain induced martensite in AISI 304 austenite steel with copper in internal friction behavior was studied. Specimens were deformed by tension from 0.03 to 0.12 of true strain at temperatures in the range -50 to 20 degrees C, in order to obtain different volumetric fractions of epsilon (HCP) and alpha' (BCC) strain induced martensites. Magnetic measurements and dilatometry were conducted to assess the quantities of induced martensite. It was found that alpha 'increases with deformation at constant temperature, and decreases as the temperature increases at constant deformation. Internal friction tests were performed in an inverted torsion pendulum in temperatures in the range of 40 to 400 degrees C. The occurrence of an internal friction peak around 100 degrees C was well established and related to the E martensite reversion. The presence of other two peaks around 220 and 350 degrees C was associated to the alpha 'present in the sample.