| Full text | |
| Author(s): |
Escobar, J. D.
;
Poplawsky, J. D.
;
Faria, G. A.
;
Rodriguez, J.
;
Oliveira, J. P.
;
Salvador, C. A. F.
;
Mei, P. R.
;
Babu, S. S.
;
Ramirez, A. J.
Total Authors: 9
|
| Document type: | Journal article |
| Source: | MATERIALS & DESIGN; v. 140, p. 11-pg., 2018-02-15. |
| Abstract | |
Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temperature, which dictates the local equilibrium conditions. Atom probe tomography and energy dispersive spectroscopy in transmission electron microscopy were used to study the austenite reversion mechanism in terms of the elemental distribution of austenite-stabilizing, ferrite-stabilizing and carbide forming elements. Synchrotron X-ray diffraction confirmed that the austenite equilibrium phase fraction was reached after 2.5 h of isothermal reversion at 625 degrees C, allowing for direct comparison with thermodynamic and kinetic calculations. However, such soaking time was not enough to produce compositional homogenization in the reverted austenite. The austenite reversion and stabilization mechanism was related mainly to strong partitioning of Ni. Negligible partitioning of Cr, Mo, Si and Ti were observed. Instead, these elements were strongly segregated at the reverted austenite/martensite interfaces. Carbon and Ti played a secondary role in the austenite stabilization through the precipitation of nano-sized Ti (C, N) with partial substitution of Ti by Mo. Virtually carbon-free austenite and martensite were observed away from the interfaces and precipitates. (C) 2017 Elsevier Ltd. All rights reserved. (AU) | |
| FAPESP's process: | 16/13466-6 - Correlative atom probe tomography and transmission electron microscopy on the study of M/A, B/A interfaces and precipitates after in situ heat treatments for a TRIP-assisted supermartensitic stainless steel and advanced high strength steel |
| Grantee: | Julian David Escobar Atehortua |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |
| 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 |