Edge Quench & Acid Etch

[jakeotter]

Hello
Need some help understanding this process.

Problem #1:
I have 1084 steel that I'm going to give it a shot edge quenching. How do I go about doing this? I've made knives doing full quench but not sure how to edge quench. I know I heat up oil as usual and just dip the edge but I've read up on it and heard about some quenching plate in the oil or something ...? Any insight on a good way to do this would be helpful!!!

Problem #2:
After the edge quench and I clean up blade, remove scale, etc... How do I go about acid etching to bring out the quench line? I've read up on this too but little confused on the process to follow and what materials I would need...

I'd appreciate and any help at all, thanks again!!!

 

[Russ Andrews]

Oil and quench plates are not used together.
1084 will not produce the active/ornate hamon that W2 or 1095 will.
If you want to have a go at it anyhow, do not attempt to quench
only the edge....the oil will flame up.....Instead, heat only the edge portion
you want to harden, then quickly submerge the entire blade & tang in
the oil.

After clean-up, you can etch in ferric chloride, or if you don't have that....use vinegar.

 

[Andy Lewis]

First off - welcome to Shop Talk!

The basic idea is to place a chunk of metal or some iron mesh in one form or another into the quench pan in order to limit the dunking depth of the blade during the actual quench operation. Some folks will tell you about a third of the blade width is about right, others will say two-thirds. I suspect more yet will tell you that you will likely be leaving some performance on the table by not taking advantage of a full quench. It is your work and your standards; so if the knife does what you think it should do then that is all that matters. Be aware though that a proper full quench on a 1084 blade will leave you with a knife that is likely both stronger and tougher than one that contains mixed structures as a result of edge quenching (e.g. pearlitic spine and mixed martensitic/pearlitic edge). That said, a lot of really great blades have been made this way for a very long time.

A common problem with edge quenching relates to inadequate volume of quenchant to properly deal with the energy carried in the austenized blade steel above it. Since the bulk never makes contact by design, this method offers a huge chance for flaming/trashing your oil as Russ just said and for auto-tempering, mixed structures of the actual cutting edge, etc. None of it good. Another problem is the limited opportunity for adequate agitation during an edge quench. Considering the thought above, this practically guarantees mixed structures in the finished edge. Finally the "rocking/rolling" motion (in and out of quenchant) against the limiter plate commonly used to quench both the edge belly and the point (all in say 3/4" oil depth) will probably leave both areas with mixed structures. Again, not good IMHO.

So you might consider adding a claying technique in combination with your full quench since you are apparently already set up for that. A full quench followed by routine tempering (and maybe a spine draw) will leave you with tempered martensite throughout that will be both harder/stronger and tougher than what could ever be expected of pearlite alone. Food for thought.

As far as etching to bring out the temper line; read up on the use of dilute ferric chloride, white vinegar, lemon juice in hamon development. The key concepts are covered here on a regular basis. Essentially you want to remove any surface decarb and get down to clean steel, then polish that to at least 320 to 500 grit followed by a thorough cleaning and several cycles of dip, soak, rinse, neutralize and polish. This can be as simple or as complicated as you want to make it. I use FeCl at about 75g/l H20 and polish with loose SiC abrasives intended for lapidary work.

To my mind, the main thing is that you work to understand why you use a particular approach rather than blindly following a given recipe. Good luck.

 

[FullyTorque]

Good tips already given. I will add that the easiest way to get FeCl for etching is to go RadioShack and pick up som PCB etchant. You'll dilute that in water, I used 16oz of PCB and about 1 gal of water. Make sure you have a acid safe container to keep it in.

Use the "search forum" feature at the top right here in Shop Talk to look up information on edge quenching, draw tempering, and etching... and anything else you have questions on. Just make sure you pay attention to the date of the posts in the thread. Don't reply to a 2+ year old thread and expect a reply from anyone.
Also, I've found that using Google with "site:www.bladeforums.com" added to the search (this limits the search just to the bladeforums site) gives the best results.
Also, if you haven't read the sticky for new makers you should. In fact it will most likely be posted in this thread by someone soon. There's a ton of VERY useful information in it.