Abstract
In this work, the creep strengthening nanoprecipitation in novel heat resistant steels strengthened by a high density of stable nanoprecipitates has been studied. The results show that the high number density of MX nanoprecipitates within the martensitic laths in these steels comes from the great amount of MX former elements present in their chemical compositions and the high dislocation density generated by the martensitic transformation that takes place during cooling after austenitization. These dislocations act as nucleation sites for these nanoprecipitates during the tempering applied after the austenitization and quenching. Atom probe tomography measurements show that these nanoprecipitates are rich in Nb, V, Cr and N for the HDSN1 and HDSN2 steels and V, Cr and N for the HDSN3 steel. The distribution of the nanoprecipitates within the martensitic laths suggests that the creep strengthening produced by the Nb, V, Cr and N nanoprecipitates in the HDSN1 and HDSN2 steels is more effective at pinning dislocations at high temperature than that obtained in the HDSN3 steel by the V, Cr and N nanoprecipitates. However, the high amount of W in the HDSN3 steel enhances the solid solution strengthening at high temperatures, resulting in a similar high temperature strength for all HDSN steels.
| Original language | English |
|---|---|
| Article number | 110982 |
| Journal | Materials Characterization |
| Volume | 174 |
| DOIs | |
| State | Published - Apr 2021 |
Funding
Authors acknowledge financial support to Spanish Ministerio de Economia y Competitividad (MINECO) in the form of a Coordinate Project (MAT2016-80875-C3-1-R). J. Vivas acknowledges financial support in the form of a FPI Grant BES-2014-069863. This work contributes to the Joint Programme on Nuclear Materials (JPNM) of the European Energy Research Alliance (EERA). APT was conducted at ORNL's Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility. The authors would like to thank James Burns for assistance in performing APT sample preparation and running the APT experiments. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Authors acknowledge financial support to Spanish Ministerio de Economia y Competitividad (MINECO) in the form of a Coordinate Project ( MAT2016-80875-C3-1-R ). J. Vivas acknowledges financial support in the form of a FPI Grant BES-2014-069863 . This work contributes to the Joint Programme on Nuclear Materials (JPNM) of the European Energy Research Alliance (EERA). APT was conducted at ORNL's Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility . The authors would like to thank James Burns for assistance in performing APT sample preparation and running the APT experiments.
| Funders | Funder number |
|---|---|
| EERA | |
| European Energy Research Alliance | |
| U.S. Department of Energy | |
| Office of Science | |
| Family Process Institute | BES-2014-069863 |
| Ministerio de Economía y Competitividad | MAT2016-80875-C3-1-R |
Keywords
- Alloy design
- Atom probe tomography
- Creep strength
- Heat resistant steels
- Microstructural characterization
- Nanoprecipitation