Recommendation? Need a little help

2fishminimum

2fishminimum

Joined
Jun 19, 2018
Messages
25
Hey folks,

So as you can see in the pictures below I have a chefs knife profiled and beveled.. I spent the better part of the day hand sanding to 2000 grit and etching in ferric chloride/h2o mixture.

this was a piece of steel i got on line, and it was .15" thick and precision ground. it consists of 5160, 15n20, 203n, and 52100

I cut the basic profile, and heat treated it, then ground the bevels in.. after that i hand sanded and etched. not sure what is causing that big line running from the curve at the bottom of the tang up to the top of the spine there..

any ideas what causes this or how to fix it?
this line was not there when I received the billet, so im sure its something I did. I did not heat the handle to the same temp as the blade.. but I did have the whole blade at non magnetic for about a 2 minute soak ( steel makers recommendation on heat treat)

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Sounds like AD steel, funny enough I'm working on a kitchen knife right now out of their damascus steel.

Hardened versus non-hardened damascus steel will etch differently. What you're seeing is probably the zone between the properly hardened steel and softer steel. Beyond the aesthetics (I think it's cool to have basically a hamon on that knife), it's a little more worrisome that there is probably softer steel at the heel of the blade edge which probably won't hold a good edge compared to the well hardened steel on the rest of the edge.

Edited to add: What quenchant did you use? If you used canola oil, it works better heated up to about 130F. A thick spine can cause autohamon in some blades because the quenchant doesn't cool the steel down fast enough to the martensite start temp.

2nd edit: Also did you carefully scrub the steel clean before etching and then only handle with clean gloves?
 
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Milkbaby, thanks so much for your answer. Yes its AD steel. I love the quality of their stuff. The knives ive made with it so far have great edge retention. my typical
process is to sand to 2000 grit, scrub with hot soap and water and dry thoroughly, then rub with acetone, then etch.. i put clean gloves on before the soap and water.

my oil is canola, heated to 130 ( according to my turkey fryer thermometer )..
This is by far the largest knife ive made in my forge.. i did have to pass the blade back and forth a lot more to cover the length, so your answer does make a lot of sense. ( too much knife for my little forge... need to upgrade to an even heat )

I suppose to fix it i can deepen the curve just a little and reshape the heel. that would eliminate the softer steel there. it was designed to be a 10" knife and the blade came out to 11.25", so I have a bit of room to play with.
 
Yep that’s the hardness transition zone. Also why did you sand to 2000 grit. I find a lower grit like 400 or 600max makes a really good finish for etching. Going up to 2000 is just a waste of time,
 
JTknives said:
Yep that’s the hardness transition zone. Also why did you sand to 2000 grit. I find a lower grit like 400 or 600max makes a really good finish for etching. Going up to 2000 is just a waste of time,
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Hey JT, thanks for the reply :)

i went to 2k grit because im a noob, and i saw it in some videos, as well as read it somewhere. ive not tried etching at 400 yet, but you can bet im gonna try now.. sanding to 2000 is seriously time consuming lol..
 
I use a lot of Damascus and only take it to 600 grit. Other guys have hit it on the head as far as the line goes.
 
Thanks everybody for the responses.
is it possible to fix? the bevels are in and the edge is pretty thin. Id be hesitant to re heat treat.. or should i just grind out the softer heel of the blade and and go with it?
 
Blade is thin now so to re hear treat could cause it to wavey warp on you
I'd grind out the soft heel and make it more square than sloped towards the handle like it is now,luckily u got room at heel to do that,square heel works better than pointy heel anyway.doesnt catch in chopping board
 
What everyone said above.

Also, the point at the heel and the very thin tip are issues in use. The heel will easily bite you … round/angle it as John suggested. The very pointy tip will likely break someday. When it does, re-profile the tip so it either curves or angles down from the spine ( sort of mini-Wharncliffe or reverse tanto).
 
Thanks everyone,
So I was making this knife for a friend, and I decided to go ahead and keep it for use in my kitchen.. Ill grind out the soft steel at the heel, and re shape the tip.. then im Going to make him a new one using the advice everyone posted here. it all seems like such good common sense that I wish I had thought of it to begin with. :)
 
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