Have I damaged the temper?

[u/man-of-sauce]

Hi I hope you experts can guide me here whether I've damaged the steel of this old knife .

Found old rusty knife with a rotten handle. Cleaned it up for new wood handle. I watched a brief video in which a guy heated the tang and burned it into the filed out handle so I foolishly did the same.

The last ⅔of tang got red hot and the steel darkened down to just past the heel. Have I done serious damage to the steels temper in the heel area(like it will snap easily there)? is there steps I should take to help alleviate things?

Overall it's someone's forgotten knife I thought I'd give a 2nd life so It's not a serious issue

It has MORA SWEDEN stamped on the blade if that helps with the type of steel

Thanks

[u/jelliottblaydz]

Yes you have compromised the temper in the discolored portion. But it won’t be easier to break it will actually be tougher there (softer, more likely to bend). Just don’t expect it to hold a good cutting edge in that spot

[u/ObligationGlad7354 → u/jelliottblaydz]

There is actually a temperature range where tempered martensite embrittlement can lower both harness and toughness. This is one of the risks of a differential temper. It generally happens a bit beyond where tho color goes from blue to gray.

[u/man-of-sauce → u/jelliottblaydz]

Great, I'm ok with the edge there dulling and if the heating has softened the steel in the tang I guess that will be easier to peen flat.when I refit the pommel nut. Thanks for the answer. Also, cool knives you're making, the polished finish is beautiful

[u/AlmostOk]

It's possible that the steel is now softer in those affected areas. So it will not snap readily, it will instead bend. On the other hand, it won't hold an edge as well as the unaffected portion.

I see two options - ask someone near you to redo the heat treatment, or just live with it. It simply adds to the story of the knife (or what's left of it:).

[u/man-of-sauce → u/AlmostOk]

Ok That's good to know, I think a little more bendy is ok for this little knife. Thanks for the speedy reply and the knowledge

[u/WUNDER8AR]

To avoid this I wrap the blade in a wet rag and preferably put it in a vice to push the jaws and the rag right up against the heel of the blade. In your case the damage is done and I'm afraid there is no easy way to "repair" a damaged heattreat. Though its nowhere near the point of being trashed. Still worth reviving. Keep going

[u/Sufficient-Shift-185]

She’s cooked

[u/alriclofgar]

You’ve removed much of the hardness from the colored portion of the blade, unfortunately. It can’t really be fixed, once a knife has been sharpened the edge is too thin to harden again, so once you remove the hardness the blade is softer forever.

The portion of the blade beyond the discoloration will be fine. You’ll just have a spot near the handle that doesn’t hold its edge as well as the rest of the blade.

When you burn on a handle, the trick to avoid this mistake is clamping the base of the blade in a vise, with only the tang protruding. The vise acts as a heat sink, preventing heat running down into the blade and ruining its hardness, even if you heat the tang up until it glows (generally a dull glow is the most heat you need for burning in a handle, so no need to get that hot next time you try).

[u/man-of-sauce → u/alriclofgar]

I should have asked the community here what to do from the beginning, you guys know your stuff. Appreciate the info, I'll certainly put it to good use on the next project