Are these big grains?

F

fateofone

Joined
Sep 21, 2016
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I'm trying to determine if i overheated my blade. Is this considered a big grain? I will say it was extremely difficult to snap it. I had to cut it extremely thin before it would snap.
UtefNi8.jpg


Also, it is a super tiny piece. I had to use a macro lens to get that.
 
big grains. it should be fine enough that it just looks gray and you cant see individual grains with the naked eye. but you check for grain size after you heat treat. i would defiantly run a normalizing grain refining cycle.
 
To check grain size, break a file and compare to that. That's a good comparison.
 
You have over heated the steel for sure. 5160 because of its alloy does not develope large grain without over heating. Heating to just above ac1 and letting it cool to black several times should reduce the grain.

Hoss
 
what is the last cooling speed of your specimen? In other words, is this pearlite, bainite or martensite?

To me your grain looks pretty big, but looking at steel like this with the naked eye is pretty difficult. For example, I once broke a piece of fine grained soft annealed pearlitic toolsteel, the grain looked huge. After hardening the same piece in martensitic phase looked very good, like a file. I think the spheroidized Fe3C clusters in the soft annealed condition make tricks on the eye. Also, don't forget the hardening will also introduce two grain refining cycles, one when forming austenite and one when forming martensite. To me this is also the reason some guys do triple hardening; 6 grain refining cyles.

More about this: http://www.koksmes.net/uploads/Redu...ern_welded_damascus_steel_v06_no_approval.pdf
 
Mess up the shape? If your not carfule when refining grain the bar will pop back to its origanial shape and you will have to start over.
 
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