Avaliação da potencialidade das técnicas de ultrassom na caracterização de aços AISI e aço inoxidável duplex.

Abstract

In this work the study of the potentiality of ultrasonic measures (velocity and attenuation) in microstructural characterization of steels AISI and duplex stainless steel was accomplished. In the study with AISI steels it was analyzed the ultrasonic velocity and attenuation behavior in microstructures different (ferrite, pearlite, ferrite-pearlite and martensite) from both thermal treatments and the content carbon variation. For the duplex steel the effect of thermal aging, at temperatures of 698 and 748K in intervals of 12, 24, 50, 100 and 200h, in ultrasonic velocity and attenuation behavior was evaluated. Velocity measures were calculated both longitudinal and transverse waves. Through the longitudinal and transverse velocities relationship, elastic constants for both materials were calculated, with and without heat treatment. In AISI steels, the sonic velocity grew from tougher phase (martensite) to softer phase (ferrite), while the sonic attenuation was the opposite. In the duplex steel, the sonic velocity increases with aging time, while the attenuation has not significantly varied. In general, the results obtained showed that both techniques are promising and may make relevant contributions to the materials characterization and control of mechanical properties through non-destructive testing.