I've got this 3D-printed martensitic steel, and I'd like to get grain size/shape distribution information. From SEM (BSE channeling contrast), the grains appear quite fine, but it's difficult to discern grain boundaries clearly.
I tried EBSD a bit but was never able to get a good scan. From what I understand, I've got these things working against EBSD: 1. very fine, possibly sub-micron grains, 2. martensite, 3. internal stresses.
Perhaps I can image-analyze the BSE images, but I'm not sure how to do that, especially given the fuzzy grain boundaries. Some (contrast enhanced) BSE images are attached. Thanks in advance.
You could try an etching first to confirm the structure and reveal the grain boundary. An etching (you may try 2% Nital) could also help you to idntify whether it is fully martensite or DP, or combination of different things. For me all these images doesn't clearly confirm the martensite features. After etching, you could observe the hexagon packets of martensites (possible with optical microscope or SEM), and analyse the packet size instead.
With EBSD, it should still be possible to get an adequate scan, however you need to prepare your sample very carefully. Preferably after grinding, first diamond polishing, and then OPS polishing. Even with the fine (sub-micron) martensite grains with high dislocation densities, you should be able to do a good EBSD scan if your detector binning is not too high.
Hi Bert,
Didn´t you think about TEM microscopy? If you have access to TEM microscope equipped by Precession System, you could get precise orientation and strain mapping with spatial resolution 2-3 nm and less. The result is EBSD-like.
I think you you should good polished sample. Afetr doing that, it will be easier for you to observe the hexagon picks and and analyse size of your martensites with SEM.
Hey, i think with a good combination of exact time etching (nital or picral) and using an analytical program (such as MIP4 or Imagej), you can get some valuable results.
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