Ferros fundidos nodulares de alta resistência obtidos por tratamento térmico de têmpera e partição: microestrutura e comportamento mecânico.

Melado, André Caetano

doi:10.11606/t.3.2018.tde-16072018-134449

Cited by 1 publication

(3 citation statements)

References 25 publications

(30 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A caracterização das propriedades mecânicas da liga de ferro fundido temperada e particionada estudada neste trabalho foi feita por Melado (2018), dentro do mesmo projeto em que se insere esta tese. Melado (2018)…”

Section: Evolução Microestrutural Das Amostras Temperadas E Particionunclassified

“…A Figura mostra como as propriedades de resistência (limite de resistência à tração) e ductilidade do ferro fundido T&P se relacionam com as propriedades de outras classes de ferros fundidos nodulares, mostrando que o material representa uma nova classe de ferros fundidos de alta resistência. Para a caracterização completa das propriedades mecânicas do ferro fundido T&P, o leitor é referenciado à tese deMelado (MELADO, 2018). Comparação das propriedades mecânicas do ferro fundido T&P com diferentes classes de ferros fundidos nodulares.…”

unclassified

“…Comparação das propriedades mecânicas do ferro fundido T&P com diferentes classes de ferros fundidos nodulares. Adaptado de(MELADO, 2018) 158…”

unclassified

See 2 more Smart Citations

Têmpera e partição de ferros fundidos nodulares: microestrutura e cinética.

Nishikawa¹

View full text Add to dashboard Cite

The present work belongs to a bigger project whose main goal is to study the technical feasibility of the application of a relatively new heat treating concept, called Quenching and Partitioning (Q&P), as an alternative to the processing of high strength ductile cast irons. The aim of the Q&P process is to obtain multiphase microstructures consisting of martensite and carbon enriched retained austenite. Martensite confers high strength, whereas austenite confers ductility. In the Q&P process, after total or partial austenitization of the alloy, the material is quenched in a quenching temperature T Q between the Ms and Mf temperatures to produce a controlled mixture of martensite and austenite. Next, at the partitioning step, the material is isothermally held at a either equal or higher temperature (so called partitioning temperature T P) in order to promote the carbon diffusion (partitioning) from martensite to austenite. The present work focus on the study of phase transformations aspects-with emphasis on the microstructural evolution and kinetics of the reactions-of the Q&P process applied to a ductile cast iron alloy (Fe-3,47%C-2,47%Si-0,2%Mn). Heat treatments consisted of austenitization at 880 • C for 30 min, followed by quenching at 140, 170, and 200 • C and partitioning at 300, 375 e 450 • C up to 2 h. The microstructural characterization was carried out by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and electron probe microanalysis (EPMA). The kinetic analysis was studied by high resolution dilatometry tests and in situ X-ray diffraction using a synchrotron light source. Results showed that competitive reactions-bainite reaction and carbides precipitation in martensite-is unavoidable during the Q&P process. The bainite reaction kinetics is accelerated by the presence of martensite formed in the quenching step. The bainite reaction occurs at low temperatures without carbides precipitation and contributes to the carbon enrichment of austenite and its stabilization. Due to carbides precipitation in martensite, growth of bainitic ferrite is the main mechanism of carbon enrichment of austenite. Microsegregation inherited from the casting process is present in the heat treated material and affects the martensite distribution and the kinetics of the bainite reaction. In regions corresponding to eutectic cell boundaries less martensite is observed and the kinetics of bainite reaction is slower. The final microestructure produced by the Q&P process applied to the ductile cast iron consists of tempered martensite with carbides, bainitic ferrite, and carbon enriched austenite. Additionally, a computational model was developed to calculate the local kinetics of carbon redistribution during the partitioning step, considering the effects of carbides precipitation and bainite reaction. The model showed that the kinetics of carbon partitioning from martensite to austenite is slower when the tempering carbides are more stable and that, when the carbides free ener...

show abstract

Section: Evolução Microestrutural Das Amostras Temperadas E Particionunclassified

unclassified

See 1 more Smart Citation

Têmpera e partição de ferros fundidos nodulares: microestrutura e cinética.

Nishikawa¹

View full text Add to dashboard Cite

show abstract

Ferros fundidos nodulares de alta resistência obtidos por tratamento térmico de têmpera e partição: microestrutura e comportamento mecânico.

Cited by 1 publication

References 25 publications

Têmpera e partição de ferros fundidos nodulares: microestrutura e cinética.

Têmpera e partição de ferros fundidos nodulares: microestrutura e cinética.

Contact Info

Product

Resources

About