In-situ experiment to improve computational tools for duplex stainless steels
| Reference number | |
| Coordinator | Swerim AB - Swerim AB, Kista |
| Funding from Vinnova | SEK 500 000 |
| Project duration | October 2018 - October 2019 |
| 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 | 2018-03260_Outokumpu_and_Sandvik_Materials_Technology_and_AlfaLaval.pdf (pdf, 437 kB) |
Purpose and goal
Cooling after welding or heat treatment is a critical process for duplex stainless steels. If cooling is slow, detrimental intermetallic phases can form, and it is too fast chromium nitride precipitates. The goal of this project was to follow the kinematics of phase transformation (using wide-angle x-ray scattering) and nitride precipitate formation (using small-angle x-ray scattering), during heat treatment or welding of duplex stainless steels and use the results to modify simulation tools to predict these changes for the future use of these materials.
Expected results and effects
We were able to provide an in-situ phase transition profile, for the three types of commonly used duplex stainless steel. The experimental data were used to verify and further develop our simulation tool that predicts the phase transformation of austenite, ferrite, and nitride precipitates upon heating and cooling of duplex stainless steels. The model is to be used as a tool for the optimization of the manufacturing process for steel producers and prolonging the lifetime of duplex steels for the end-users of these materials.
Planned approach and implementation
In-situ dilatometry and Wide-Angle X-ray scattering were performed to allow quantification of the austenite and ferrite fraction during heating and cooling of duplex steels. Small-Angle X-ray Scattering measurements were performed on the samples after the treatment to quantify the nanosize chromium nitride precipitates formed during cooling. The experiment was performed on the High Energy Materials Science beamline (P21) at the German synchrotron radiation source Petra III in Hamburg. Simulation tools were used to correlate the nitride precipitation with the austenite fraction within the sample.