Question: Engraving knife blades / hardening

[Alveprins]

Ok, so I will be doing engraving and gold inlay into a knife blade.

Now my question is, what do I do with the hardening and heat treatment of the blade?

Should I:

1. Fully harden the entire blade, then engrave? (Hardness will be around 58 HRC

)
2. Engrave, then harden, then do gold inlay?
3. Cover the body of the knife with clay (Japanese differential hardening) to leave the body softer than the edge?
4. Quench the edge only in a pan of water/oil as to leave the body soft for engraving?
5. Fully quench the entire blade, then soften the body of the knife with a blowtorch while keeping edge submerged in water - and then engraving?

Anyone have experience with this?

Any input would be really great.

Sincerely, Alveprins.

 

[davesa]

Not saying I am an expert, or that I have done this before so certainly listen to the opinions of others as well. Also I don't know the size of the knife, or the complexity or style you plan to engrave

1.) if you do this you would need to use hard gravers, like carbide and I think think the time required would go way up. Similar to the way knifemakers grind a blade while annealed, get it close, then harden. Just like grinding a hard blade uses more belts, would you be sharpening more?
2.) if you engrave, then harden - even if you carefully wrap it in stainless foil while heat treating, you will get some discoloration / oxidation on the blade, which would benefit your cuts, but leave you with an issue of how to fix the areas you wanted bright.
3.) certainly a possibility, depending on the steel you might even have a cool looking hamon, but would that add to or detract from your engraving
4.) you might not have as distinct a hamon as with clay perhaps and the part you want to engrave would be softer. This seems workable. watch for adding a curve to the blade you do not intend.
5.) Harder to keep the heat just to the back unless it is a big knife... how do you make sure you do not lose your temper on part of the blade. Seems similar in concept to 4 above, but with additional risk in potentially losing hardness on part of the edge.

Hope that helps

 

[John B.]

If I had my choice I would shape the blade and bring it close but not to finish polish.
Then with the blade still in the soft state, create the cavities and bur field.
Inlay the precious metal, sand or stone it to just short of finish level.
Then clay coat the blade Japanese style and heat harden just the cutting edge.
Strip the clay, flush down the inlay, final finish the blade and detail the engraving.