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Microstructural Modification and Bendability Improvement in 1300 MPa Steel via Induction Surface Heat Treatment

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Abstract:

This study investigates the effect of induction-based surface heat treatment on the microstructure and bendability of a commercial hot-rolled martensitic steel with a nominal strength of 1300 MPa. A rapid tempering process was applied at 500 °C and 700 °C using a pilot-scale 60 kW induction heating system, followed by water quenching. Microstructural characterization revealed that the treatment induced minor changes near the subsurface without affecting the centerline. The as-rolled condition exhibited the highest subsurface hardness, whereas surface-treated samples showed progressive softening due to recovery. Three-point bending tests combined with digital image correlation demonstrated a significant improvement in bendability for heat-treated samples. The as-rolled condition fractured at 0.195 strain, while the 700 °C treated specimen did not fracture even at 0.78 strain. These findings highlight that even a modest reduction in subsurface hardness can substantially enhance the formability of ultra-high-strength steels, offering a promising approach for industrial applications requiring high strength and improved bendability.

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Periodical:

Solid State Phenomena (Volume 388)

Pages:

39-45

DOI:

https://doi.org/10.4028/p-L9atJa

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Cite this paper

Online since:

April 2026

Authors:

Antti Kaijalainen*, Ahmed Abdelghany, Oskari Haiko, Anttu Jouni Topias Hoikkaniemi, Aki Petteri Pokka

Keywords:

Bendability, Hardness, Induction Heating, Soft Surface, Ultrahigh-Strength Steel

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Creative Commons CC BY 4.0

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