Harry at the National Taiwan University (September 2023)
Commercially viable strong steel with austenite grain size less than 0.4 μm
It is assumed that high-carbon martensite is strong but brittle. We teach therefore, that it must be somewhat tempered even though that is at the expense of strength. In this talk, I will demonstrate both experimentally and using theory, that this is not true if the crystallographic grain size can be reduced dramatically.
The scale of reduction in this grain size must be so large that it becomes difficult to transfer stress on to individual martensite plates. The way in which this can be achieved is by a combination of austenite grain size control and the sub-division of the austenite into domains that have different orientations. When only 24 crystal variants of martensite can form in a normal austenite grain, it is shown that thousands of variants are possible per austenite grain that has been “fragmented”.
Furthermore, there is a demonstrated route to large scale production. Applications in real situations have shown the viability of the product.
The talk was followed by a lovely vegan-dinner with Professor Jer Ren Yang's team and NTU staff.
Poster advertising Harry's talk |
Harry, wearing a storm jacket, since a typhoon was predicted but did not reach Taipei apart from mild rain. |
The temperature was comfortable, at 303 K |
About 200 people, from two Universities and a variety of subject backgrounds attended. In the foreground is Professor Yang, wearing his Cambridge University tie |
There were many interesting questions asked by students |
This is a menu from a nice lunch place very close to the National Taiwan University. |
The insides of a sophisticated, aberration-corrected, transmission electron microscope at NTU |
Dinner at a delicious vegan restaurant, where we could chose and eat as much as we like. The team here is from Professor Yang's group |
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