Abstract
Continuous cooling transformation (CCT) diagrams represent roadmaps for producing all
heat-treatable steels. CCT curves provide valuable information on the solid-state phase
transformation sequence, depending on the defined cooling strategies, the alloying concept
of the steel and previous processing steps. The experimental characterization of CCT diagrams
is usually done on a laboratory scale applying thermal analysis of dilatometry. In
current research studies, however, also other in-situ methods such as high-temperature
laser scanning confocal microscopy (HT-LSCM) or differential scanning calorimetry (DSC)
are frequently used to investigate phase transformations during thermal cycling. In the present study, HT-LSCM observations and DSC analysis are critically compared with dilatometry results by investigating the CCT diagram of a 0.4%C-1.8%Si-2.8%Mn-0.5%Al (in mass pct.) advanced steel grade. Furthermore, classical examinations by optical microscopy and hardness measurements were performed to support the analysis. In general, very good consistencies between all experimental techniques were identified in determining the transformation start temperature for pearlite, bainite and martensite. The optical microscopy confirmed the observed phase transformations and the results correlated with the measured hardness response. Based on the results, coupling of HTLSCM and DSC is considered as a valuable novel approach to plot CCT diagrams in future research.
heat-treatable steels. CCT curves provide valuable information on the solid-state phase
transformation sequence, depending on the defined cooling strategies, the alloying concept
of the steel and previous processing steps. The experimental characterization of CCT diagrams
is usually done on a laboratory scale applying thermal analysis of dilatometry. In
current research studies, however, also other in-situ methods such as high-temperature
laser scanning confocal microscopy (HT-LSCM) or differential scanning calorimetry (DSC)
are frequently used to investigate phase transformations during thermal cycling. In the present study, HT-LSCM observations and DSC analysis are critically compared with dilatometry results by investigating the CCT diagram of a 0.4%C-1.8%Si-2.8%Mn-0.5%Al (in mass pct.) advanced steel grade. Furthermore, classical examinations by optical microscopy and hardness measurements were performed to support the analysis. In general, very good consistencies between all experimental techniques were identified in determining the transformation start temperature for pearlite, bainite and martensite. The optical microscopy confirmed the observed phase transformations and the results correlated with the measured hardness response. Based on the results, coupling of HTLSCM and DSC is considered as a valuable novel approach to plot CCT diagrams in future research.
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 3534-3547 |
| Seitenumfang | 14 |
| Fachzeitschrift | Journal of Materials Research and Technology |
| Jahrgang | 24.2023 |
| Ausgabenummer | May-June |
| DOIs | |
| Publikationsstatus | Veröffentlicht - 17 Apr. 2023 |
Bibliographische Notiz
Funding Information:Michael Bernhard, Maximilian Kern, Peter Presoly and Christian Bernhard gratefully acknowledge the financial support under the scope of the COMET program within the K2 Center “ Integrated Computational Material. Process and Product Engineering (IC-MPPE) " (Project No 859480 ). This program is supported by the Austrian Federal Ministries for Climate Action, Environment, Energy, Mobility, Innovation, and Technology (BMK) and for Digital and Economic Affairs (BMDW), represented by the Austrian research funding association (FFG), and the federal states of Styria, Upper Austria and Tyrol. This research was also partially supported by the Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea ( NRF-2022H1D3A2A01081708 ). Man Liu gratefully acknowledges the support from the State Scholarship Fund of the China Scholarship Council . Monika Kawuloková, Josef Walek, Simona Zlá, Bedrich Smetana and Marketa Tkadlečková gratefully acknowledge the financial support for the project No. CZ.02.1.01/0.0/0.0/17_049/0008399 from the European Union and Czech Republic financial funds provided by the Operational Programme Research, Development and Education , Call 02_17_049 Long-Term Intersectoral Cooperation for ITI, Managing Authority: Czech Republic-Ministry of Education and student grant project SP2023/034 and SP2023/022 .
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© 2023 The Author(s)