I would like to know if there is a mechanism for pearlite diffusion, segregation or cementite partially decomposition in 0.08%C steel after heating up to 800oC ( higher than eutectoid temperature) for 30 min. Microstructure before heating includes ferrite and pearlite while pearlite seems to be invisible in microstructure after heat job.EBSD Phase analysis showed cementite exists randomly in the ferrite matrix of the latter one.
I am not an expert in microstructure evolution during heat treatment. Does anyone have experience related to my question? Please give me some ideas. I greatly appreciate it. Thank you!
It is very hard to get EBSD map of pearlite that will reveal cementite on phase map. I think the randomly distributed points of cementite can related to locally observed low quality patterns and misindexing but without seeing the map, SE-BSE images and some patterns from these points it is not easy to judge.
Hi,
If you mean that after EBSD you have only two phases: ferrite and cementite it does not mean that perlite is invisible. Actually, ferrite phase in EBSD covers all the bcc structured phases including ferrite, pearlite, bainite and even martensite. In the better words, it is not possible to use EBSD phase map for distinguishing ferrite from pearlite.
The one possibility is using SEM/FESEM for the details inspection of microstructure and the other one is using microhardness to see how much is the hardness of different morphologies in the microstructure. The hardness value could be a good indicator for distinguishing ferrite and pearlite as they have different hardness value.
Grzegorz Cios Thank you so much for your answer.
Honestly, I confused about the presence of Cementite after the heat job and finding the way to clear about it so I did EBSD phase analysis. I totally agree with you about the probability of misindexing and low-quality patterns lead to such randomly distributed cementite points. Do you know another way to confirm whether Fe3C exists or not? I am trying to understand what happened to pearlite during heating that makes it disappear. There is 0.08% C in my material then which form they are after applying heat treatment.
Vahid Javaheri
Thank you
I just wonder about the transformation of microstructure after heating. Original material microstructure after etching has pearlite and ferrite. I could clearly detect pearlite colonies with a lamella structure consisting of cementite and ferrite. But heat-treated material doesn't show lamella structure as before. After etching, it seems a single ferrite microstructure. How can I say pearlite still exists?
Grzegorz Cios thanks for the correction
I meant different bcc morphologies
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Thao Phuong Bui Can you share the microstructure before and after heat treatment + rate of heating and cooling?!
Good question from Vahid. It would be interesting to know also the complete chemical composition (Si, Mn ...) of the steel and his history (cast, rolled, homogeneization heat treatment ....).
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