METHOD FOR OBTAINING JOMINY HARDENABILITY CURVES FROM THE MODELING OF CONTINUOUS COOLING DIAGRAMS OF MEDIUM CARBON AND LOW-ALLOY STEELS
Camila Assunção Roque1; Maíra Freitas Alves Ferreira1; Valter José Pereira Matos1; André Barros Cota2; Pedro Paiva Brito1; Sara Silva Ferreira de Dafé1
1 Mechanical Engineering Department, Pontifical Catholic University of Minas Gerais; 2 Physics Department, Federal University of Ouro Preto, University Campus
doi:10.20906/CPS/COB-2015-1698
Resumo
The hardness of steels can be increased by quenching heat treatment whereby the material is austenitized and then submitted to fast cooling. The material hardness will be related with the generated microstructure, which can be predicted by knowing its transformation diagrams. The experimental determination of this diagrams is sometimes difficult and laboriout. In this study, a mathematical model was applied to determine the continuous cooling transformation curves from the steels chemical compositions and based on the austenite decomposition kinetics reaction. The model was applied to AISI 1045, 4140 and 4340 steels which allowed the determination of the phases volume fraction for each cooling rate. The thermal cycles prediction allowed the calculation of Jominy hardenability curves. The model validation was made trough experimental analysis such as dilatometry, metallography and hardenability Jominy tests. The experimental data associated with the used methodology endorsed the validity of the mathematic model for the medium carbon and low-alloyed steels.
Palavras-chave: Hardenability; Jominy Test; CCT Diagram; Mathematical Modeling