Commercially viable strong steel with a grain size of just 0.4 µm
Channel: bhadeshia123
Date: 2023-05-22

A lecture delivered at the Future Metallugy Forum, organised by Professor Zhongyun Fan who is also the Director of the EPSRC Liquid Metal Engineering hub at Brunel University.

The idea that strong high-carbon martensite is brittle in its virgin condition is embedded firmly in metallurgical convention. The brittleness is apparent in optical microscopy that reveals periodic cracking. The cracks are not caused by the application of an external stress, but form spontaneously under the influence of thermal or transformation stresses, as the microstructure evolves. 

The tendency for such cracking diminishes as the austenite grain size is reduced. This is because it becomes difficult to transfer stress on to an individual martensite plate as its dimensions decrease. 

The talk shows how to achieve a dramatic decrease in the crystallographic grain size so that strength and toughness can coexist in harmony.

This recording has kindly been provided by the organisers of the Future Metallurgy meeting.

https://www.phase-trans.msm.cam.ac.uk/