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Master's Dissertation
Full name
Leandro Gomes de Carvalho
Knowledge Area
Date of Defense
São Paulo, 2011
Padilha, Angelo Fernando (President)
Plaut, Ronald Lesley
Terada, Maysa
Title in Portuguese
Estudo dilatométrico das transformações de fase em aços maraging M300 e M350.
Keywords in Portuguese
Aços maraging
Reversão da martensita para a austenita
Abstract in Portuguese
Os aços maraging são aços de baixo teor de carbono com estrutura martensítica (CCC), que são endurecidos pela precipitação de fases intermetálicas. O objetivo deste trabalho é estudar as transformações de fases desses aços: precipitação, reversão da martensita para a austenita e transformação martensítica. Nesse trabalho, foram caracterizadas uma corrida de aço maraging da série 300 e três corridas da série 350, usando diversas técnicas complementares: microscopia ótica, microscopia eletrônica de varredura com análise dispersiva de energia, microdurômetro, difração de raios-X, ferritoscópio e dilatometria. Os resultados obtidos mostraram que as corridas com maiores teores de cobalto e titânio apresentaram maiores valores de microdureza nos estados solubilizado e envelhecido. Por outro lado, medidas dilatométricas mostraram que há uma influência significativa tanto da composição química, quanto da taxa de aquecimento nas reações de precipitação e reversão da martensita para a austenita. No entanto, a transformação martensítica mostrou-se dependente apenas da taxa de aquecimento.
Title in English
Study dilatometric of the phase transformations on maraging steels M300 and M350.
Keywords in English
Austenite reversion
Maraging steels
Martensite to austenite reversion
Abstract in English
Maraging steels are steels with a low carbon martensitic structure (BCC), which are hardened by precipitation of intermetallic phases. The aim of this work is to study the phase transformations of these steels: precipitation, martensite to austenite reversion and martensitic transformation. In this study, one cast of 300 grade and three casts of 350 grade were characterized using several complementary techniques: optical microscopy, scanning el ectron microscopy with energy dispersive analysis, microhardness, X-ray diffraction, ferritoscope and dilatometry. The results showed that the casts with higher concentrations of cobalt and titanium showed higher microhardness in the solution annealed and aged states. On the other hand, dilatometry measurements showed that there is a significant influence of both the chemical composition and the heating rate on the reactions of precipitation and reversion of martensite to austenite. However, the martensitic transformation was dependent solely on the heating rate.
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  • CARVALHO, LEANDRO GOMES DE, et al. A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates [doi:10.1590/s1516-14392013005000069]. Materials Research (São Carlos. Impresso) [online], 2013, vol. 16, p. 740-744.
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