Unusual microstructure of martensitic stainless steel
Unusual microstructure of martensitic stainless steel
(OP)
Hi all,
I have prepared an etched martensitic stainless steel and it appears differently from what is expected. This stainless steel was not used in high temperature application.
I have done some research and the microstructure observed could be a highly tempered martensite or annealed spheroid (see Photograph no.1 at 1000X).
Could anyone advise whether it is a highly tempered martensite or annealed spheroid?
Apart from this, there are clumps of particles throughout the microstructure which I have never seen before (see Photographs below, 100X and 400X).


Could anyone advise on this? Is this aggregation of spheroids?
Many thanks.
I have prepared an etched martensitic stainless steel and it appears differently from what is expected. This stainless steel was not used in high temperature application.
I have done some research and the microstructure observed could be a highly tempered martensite or annealed spheroid (see Photograph no.1 at 1000X).
Could anyone advise whether it is a highly tempered martensite or annealed spheroid?
Apart from this, there are clumps of particles throughout the microstructure which I have never seen before (see Photographs below, 100X and 400X).


Could anyone advise on this? Is this aggregation of spheroids?
Many thanks.





RE: Unusual microstructure of martensitic stainless steel
RE: Unusual microstructure of martensitic stainless steel
What was the heat treatment supposed to be?
By spec these are usually delivered in the annealed condition.
I would like to see some un-etched micros (use polarization or DIC to get some contrast).
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P.E. Metallurgy, Plymouth Tube
RE: Unusual microstructure of martensitic stainless steel
Thank you for the comments.
The etchant used was Kalling's No 2. Hardness is yet to be checked. It contains about 15 % Cr, 0.75% Ni and 0.95% Mo. I do not know the actual C level. I think it is an annealed form. What I am puzzled is the cluster of the "dark" particles, which i have no idea what that is. It can be seen throughout the etched microstructure.
RE: Unusual microstructure of martensitic stainless steel
RE: Unusual microstructure of martensitic stainless steel
Maui
RE: Unusual microstructure of martensitic stainless steel
To repolish you will have to back to fairly coarse abrasive to cut the etch pits out.
Give us a shot un-etched.
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P.E. Metallurgy, Plymouth Tube
RE: Unusual microstructure of martensitic stainless steel
Maui: Thank you for the comment. The time elapsed was about 1 minute.
EdStainless: Below is the unetched microstructure at 100X (taken before etching with Kalling's 2). The dark spots observed are inclusions. Hardness is approximately 50HRC.
RE: Unusual microstructure of martensitic stainless steel
RE: Unusual microstructure of martensitic stainless steel
I don't see any massive structures.
Can you give us a shop polarized or DIC?
Perhaps a less aggressive etch such as Fry's would work better.
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P.E. Metallurgy, Plymouth Tube