1095 Pearlite or Martensite ?

Tod Lowe

Tod Lowe

Well-Known Member
Hey guys.
I quenched this 1095 last night in Mcmaster 11 sec oil. Unfortunately I took it a little to thin before quench and warped it then snapped it trying to fix it.......actually snapped two blades.:eek: So it was a good chance to bring it in and test Rockwell's after the quench and before tempering. 64 is what 1095 is supposed to be.
The knife has been sanded clean on both sides in the section im testing.

My question is about pearlite versus Martensite. How do you know which you have? My understanding is both are hard. Is there a way a layman can check this?
 

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You seldom get 100% pearlite or 100% martensite. If it read 62 as quenched you'd have a problematic mixture of both. If it reads 64.8 you did good. You might get that last little bit with better agitation or a faster oil, but I doubt you'd be able to tell any difference without using a microscope. 1095 can probably achieve about one more point of hardness (meaning a slightly more homogeneous fully martensitic structure), but most anybody would be very happy with what you got.

If your fractures look smooth and milky you have fine grain. If you're fractures look flakey or pebbly you might have a problem.
 
It is hard to say exactly. There are variables such as the exact composition of the steel and grain size. Even though 1095 is a simple steel there can be variation in manganese levels that can effect depth of hardening as well as the fact that if it's recycled steel (a good chance that it is) there may be traces of other elements that wouldn't be found in "virgin" steel that will also effect the depth of hardening. Along with the grain size, depth of hardening increases with grain size, it will effect the maximum thickness that that martensite will form at. As quenched, the steel will be a combination of martensite, pearlite, retained austinite, and probably some carbides (deffinantly with 1095). There is no way that I know of to find out the exact composition of the crystals without sending it off to a lab for analysis. If you want to get into the science of heat treating I would recommend "Steel Metalurgy for the Non-Metalurgist".

Doug Lester
 
Thanks for testing and posting results. I've been using 1095 & 11 sec. oil but have no way to test. I've broke a couple pieces and the grain looked silky smooth. By the way, how thick was the test piece?
 
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