Análise da influência de tratamentos térmicos em diferentes temperaturas de solubilização e envelhecimento na microestrutura e dureza de aços maraging classe 300.

Abstract

Maraging steels have low amount of carbon in a quaternary alloy containing nickel, cobalt, titanium and molybdenum. The hardening mechanism in these steels does not involve carbon reactions, but rather a martensitic matrix hardening due to the formation of intermetalic precipitates during the age hardening. The interest in the development of researches on these steels occurred mainly due to the growth of aeronautical, naval and nuclear industries in the last dacades. The present work aims to conduct a comparative study of the influence of traditional heat treatment of the martensite phase, called maraging, with an alternative treatment carried out in the austenite phase, called ausaging. For this purpose, a metallographic preparation was carried out in the specimens, followed by microestructure analysis in optical microscope and Rockwell C hardness test. At the end of this work it was possible to observe different microestructures resulting from different heat treatments, as well as different hardness values in the studied specimens. The plate-like and lath-like morphologies were found in all specimens, characteristic of martensite matrix. However, in the specimens submitted to ausaging heat treatment, the microstructure was quite different from the other treatments, since, in this treatment, only the phase austenite was aged, causing larger amounts of this phase in the specimens. Thus, the specimens submitted to ausaging heat treatment obtained lower values of hardness.