Strength and toughness of clean nanostructured bainite

M. J. Peet, A. Al-Hamdany, L. C. D. Fielding, P. Hill, M. Rawson and H.K.D.H. Bhadeshia

Materials Science and Technology, 33:10, 1171-1179, 2017.

DOI: 10.1080/02670836.2016.1271522


Bainite, Microstructure, Mechanical Properties, Fatigue.


A nanostructured steel has been produced using a clean steel- making technique. The mechanical properties have been comprehensively characterised. The maximum strength of the material recorded was 2.2 GPa at yield, with an ultimate tensile strength of 2.5 GPa, accompanied by a Charpy impact energy of 5 J, achieved by heat treatment to refine the prior austenite grain size from 145 to 20 μm. This increased strength by 40% and the Charpy V-notch energy more than doubled. In terms of resistance of the hardness to tempering, the behaviour observed was similar to previous alloys. Despite reducing the hard- ness and strength, tempering was observed to reduce the plane-strain fracture toughness.