What We Study
Research Areas
Spanning fundamental solid-state transformation science to applied alloy engineering — addressing challenges in rail, energy, aerospace, structural, hydrogen infrastructure, automotive and cryogenic applications.
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⚙️ Carbide-Free Bainitic Steels
Development of continuously cooled carbide-free bainitic rail and structural steels. Transformation kinetics, prior austenite grain size effects, and the influence of prior bainite/martensite on subsequent transformation behaviour and mechanical properties.
Rail Steels · Thermodynamics & Kinetics ·Processing
🔄 Deformation-Induced Martensite
Mechanisms and crystallographic variant selection of stress- and strain-induced martensitic transformation in AISI 316L austenitic stainless steels and bainitic steels. EBSD analysis of transformation textures and their role in TRIP-assisted deformation.
TRIP Effect · EBSD · Variant Selection
📊 Retained Austenite Stability
Deconstructing mechanical and chemical stability of retained austenite in two-phase and bulk microstructures. In-situ synchrotron X-ray diffraction studies at KTH Sweden tracking strain-induced austenite decomposition in real time during tensile deformation.
In-Situ XRD · Stability · TRIP
🛤️ Wear & Tribology of Rail Steels
Comparative dry rolling/sliding wear behaviour of pearlitic and carbide-free bainitic rail steels. Correlating retained austenite content, work hardening capacity, lath morphology, and subsurface microstructure evolution with damage mechanisms.
Wear · Rail · RCF · Tribology
🧮 Computational Alloy Design
CALPHAD-based thermodynamic modelling of Fe-Mn-Al-C lightweight steels and Cr-based alloys, Dual-phase microstructure evolution, genetic algorithm-assisted optimisation of alloy composition and heat treatment routes.
CALPHAD · DICTRA· ML
❄️ Cryogenic & Special Alloys
7% Ni cryogenic steels with epsilon martensite and retained austenite for LNG storage; Ce-alloyed low-carbon steels; Cu-based wear-resistant steels; grain-oriented electrical steels — extending expertise beyond conventional rail alloys to new engineering families.
Ni Steels·Cryogenic Applications · LNG
Key Findings
Research Highlights
Significant outcomes from the PTAD research group over the past decade.
01 · Product Development
Superior Wear Resistance of Carbide-Free Bainitic Rail Steel
Carbide-free bainitic rail steel outperforms conventional pearlitic rail as well as commertial martensitic wear resistant steels in dry rolling/sliding wear — attributed to high retained austenite, superior work hardening, and fine lath bainitic ferrite. Redefined rail steel benchmarks globally.
Wear · 2018, 2026
03 · Microstructure Engineering
Bimodal Ferrite Grain Size & Tensile Properties
Established quantitative relationships between bimodal ferrite grain size distributions and tensile properties, providing a design strategy for simultaneous strength and ductility improvement in structural steel grades.
Mater. Sci. Eng. A · 2012
05 · In-situ Synchrotron
Deconstructing Austenite Stability using In-situ Experiment & HEXRD
Conducted in-situ synchrotron XRD experiments at KTH to understand the stability of retained austenite in one-phase and two-phase microstructures during tensile deformation — yielding real-time quantitative transformation kinetics data.
Met. Mat. Trans. A · 2024(1 & 2)
07 · Fundamentals of Bainite Transformation
Thermal stabilizatioon and Influence of PAGS
One of the pioneering work on how prior-bainite thermally stabilizes the remaining austenite, delaying further bainitic transformation at lower temperatures. Another work investigates the effect of prior austenite grain size (PAGS) on bainite transformation kinetics in a low-alloy, carbide-free bainitic steel using dilatometry, with quantitative analysis through kinetic models to clarify inconsistencies reported in previous literature.
Philosophical Magazine · 2020(1 & 2)
02 · Processing Innovation
Continuously Cooled Bainitic Rail Steel
Developed a viable processing route for carbide-free bainitic rail steels via continuous cooling — eliminating costly isothermal treatment while achieving exceptional microstructures and properties ready for industrial adoption.
Mater. Sci. Eng. A · 2019, 2020
04 · Texture & Crystallography
Deformation Induced Martesite & Variant Selection in CFB and AISI 316L Stainless Steel
Addressed orientation dependence of DIM transformation in carbide-free bainitic steel, and mapped crystallographic variant selection rules governing the DIM transformation in AISI 316L SS under uniaxial tension, providing a framework for predicting transformation textures in these steels.
Met. Mat. Trans. A · 2020
Mater. Sci. Eng. A · 2023
06 · Cryogenic Alloy Design
Epsilon Martensite in 7% Ni Cryogenic Steel
Demonstrated that co-formation of epsilon martensite and retained austenite alongside low matrix strain in 7% Ni steel produces exceptional cryogenic strength-toughness balance — opening new design space for LNG containment.
Materialia · 2024
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