Austenite reversion kinetics and stability during tempering of an additively manufactured maraging 300 steel

Author(s)

Conde, F. F. ^[1] ; Escobar, J. D. ^[2] ; Oliveira, J. P. ^[3] ; Jardini, A. L. ^[4] ; Bose Filho, W. W. ^[1] ; Avila, J. A. ^[5]

Affiliation

^[1] Univ Sao Paulo, Dept Mat Engn, Av Joao Dagnone, 1100 Jd Sta Angelina, BR-13563120 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Met & Mat Engn Dept, 10 Av Prof Mello Moraes 2463, BR-05508030 Sao Paulo, SP - Brazil

^[3] NOVA Univ Lisbon, NOVA Sch Sci & Technol, Dept Mech & Ind Engn, UNIDEMI, P-2829516 Caparica - Portugal

^[4] Univ Estadual Campinas, Fac Chem Engn, Natl Inst Biofabricat BIOFABRIS, Av Albert Einstein 500, BR-13083852 Campinas, SP - Brazil

^[5] Sao Paulo State Univ, UNESP, Campus Sao Joao da Boa Vista 505, Av Profa Isette, BR-13876750 Sao Joao Da Boa Vista, SP - Brazil

• Document type: Journal article
• Source: ADDITIVE MANUFACTURING; v. 29, OCT 2019.
• Web of Science Citations: 0

Abstract

Reverted austenite is a metastable phase that can be used in maraging steels to increase ductility via transformation-induced plasticity or TRIP effect. In the present study, 18Ni maraging steel samples were built by selective laser melting, homogenized at 820 degrees C and then subjected to different isothermal tempering cycles aiming for martensite-to-austenite reversion. Thermodynamic simulations were used to estimate the inter-critical austenite + ferrite field and to interpret the results obtained after tempering. In-situ synchrotron X-ray diffraction was performed during the heating, soaking and cooling of the samples to characterize the martensite-to-austenite reversion kinetics and the reverted austenite stability upon cooling to room temperature. The reverted austenite size and distribution were measured by Electron Backscattered Diffraction. Results showed that the selected soaking temperatures of 610 degrees C and 650 degrees C promoted significant and gradual martensite-to-austenite reversion with high thermal stability. Tempering at 690 degrees C caused massive and complete austenitization, resulting in low austenite stability upon cooling due to compositional homogenization. (AU)

• FAPESP's process: 14/20844-1 - In situ study on kinetics of phase transformations and thermal stability of retained austenite in TRIP-assisted advanced high strength steel
• Grantee: Julian David Escobar Atehortua
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/00691-0 - Microstructural assessment of additive manufacturing parts towards aeronautic application
• Grantee: Julian Arnaldo Avila Diaz
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/17697-5 - Mechanical and microstructural assessment of additive manufacturing parts made up of 18%Ni Maraging 300 steel towards aeronautic application.
• Grantee: Julian Arnaldo Avila Diaz
• Support Opportunities: Regular Research Grants