High-resolution characterisation of secondary carbide precipitation in martensitic steels
| Reference number | |
| Coordinator | Swerim AB - Swerim AB, Kista |
| Funding from Vinnova | SEK 500 000 |
| Project duration | November 2018 - January 2020 |
| Status | Completed |
| Venture | Research infrastructure - utilisation and collaboration |
| Call | Research infrastructure - utilisation and collaboration: Industrial pilot projects for neutron and photon experiments at large scale research infrastructures - 2018 |
| End-of-project report | 2018-04412_SSAB_and_ Uddeholm_Tooling.pdf (pdf, 184 kB) |
Purpose and goal
The micro-to-nanostructure in commercial steels is complex with the occurrence of local deviations. At the same time, the structure is crucial for the material´s properties like hardness and strength. More traditional measurement methods such as TEM and APT analyze a local sample volume and make it difficult to obtain a complete picture of the nanostructure. The purpose of the project is to use SANS to characterize larger sample volumes but still with a similarly detected length scale (1-100 nm). Samples from SSAB Borlänge and Uddeholm have been studied, focusing on carbide structure.
Expected results and effects
Clear signals from different particle types in different size ranges could be detected. The results correlate well with the data from TEM and APT, regarding precipitation sequence and size and shape of the particles and allows the size distribution to be determined with very good statistics. More in depth data analysis is planned together with verification of physical based models using the results.
Planned approach and implementation
Ex-situ SANS experiments were performed based on laboratory heat-treated production materials at the Sans 2D beamline of ISIS Neutron & Muon Source, UK. A total of 12 samples were evaluated. The intention was also to perform in-situ measurements with the same set-up as the ex-situ experiments, but when the intensity was low for the main size range of interest, the detectors were adjusted to increase the intensity. New and additional ex-situ experiments were done with the new set-up, and thus there was no time to perform in-situ experiments with this set-up, which probably could have been carried out if more time.