Sir/Madam
I want to increase the CSL 3 fraction (i.e. mainly increase the twins ) just by any of the heat treatment technique (annealing ,tempering etc).
The history of the sample is hot rolled mill annealed.
I dont want to impart any cold work to the sample .
I just want to increase CSL boundaries by using heat treatment techniques.
Is it possible ???
If yes , what is the best conditions to do?
Regards
santosh
From a simple crystallographic point of view I would expect, yes. The locally high deformation will be reduced during heat treatment. The slightly rearrangement of atoms may generate sufficient stress, that stress- induced twinning may occur. However, which material exactly which temperature needs, and whether the produced stress is high enough, is quite difficult to predict. However, I am no material scientist...only crystallographer :-).
A small hint: if you are really interested in twins you should not use CSL 3. Twins are much better defined than the Brandon criterion of CSLs. I know, many people do it because it is often used in this sense....and sometimes a satisfying reason might exist.
Low and medium stacking fault energy metals usually contain annealing twins. For example, brass generates deformation twins and microtwins under severe plastic deformation and then being heated above 200C experiences recrystallization with formation of annealing twins. So all you need is to reduce the stacking fault energy since annealing twins are generated from stacking faults
Your austenitic stainless steel was mill annealed, which was likely solution annealed to remove as much as the stored internal energy induced by the hot rolling. In this case, you are unlikely to increase CSL3 boundaries solely by heat treatments. You have to introduce energy into the material (e.g., by cold work) to activate grain boundary reactions during heat treatment for CSL3 increases.
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