About this Abstract |
Meeting |
MS&T23: Materials Science & Technology
|
Symposium
|
Advances in Ferrous Metallurgy
|
Presentation Title |
In-situ Laser Ultrasonic Measurements of Phase Transformation Kinetics on Dual-phase Steels During Stepped Cooling |
Author(s) |
Nobumasa Hayashi, Mariana Mendes Rodrigues, Matthias Miltzer |
On-Site Speaker (Planned) |
Mariana Mendes Rodrigues |
Abstract Scope |
Dual-phase (DP) steels are among the advanced high-strength steels used in automotive design. To achieve optimal mechanical properties the control of phase transformations during processing is paramount, making sensor technologies that can in-situ monitor phase transformations of considerable interest. Laser ultrasonics (LUS) has been gaining increasing attention as a technique for in-situ monitoring of microstructure evolutions. In this study, phase transformation kinetics of two DP steels were measured by LUS during stepped cooling treatments, which were designed to simulate the cooling paths on the run-out table in hot strip mills. LUS measurements were first validated with well-stablished dilatometry measurements during continuous cooling. For the stepped cooling tests, the fractions transformed obtained from the ultrasonic velocity changes agree with the ferrite phase fractions as characterized by ex-situ metallography. Further, the velocity changes were described by the JMAK approach using parameters that are consistent for the austenite-to-ferrite transformation in low-carbon steels. |