Avoiding quench lines

N

Nats

Joined
Jan 13, 2005
Messages
54
I will be doing my first heat treat soon (0-1 steel) and have a question re: quench lines on the finished blades. I will be going for a hard edge/soft spine and would like to avoid the quench line marking on the finished product. Will this line grind/sand/buff out, or will it be all the way through the quenched area?

Now if I heat the whole blade to temp (non-magnetic) and quench the edge for a few seconds first (till the smoke and fire have died down a bit?), then totaly submerge the rest of the blade, will I still have the mark and will the ratio of hard edge/soft spine still be there?

I will have a couple of smaller skinner-ish blades to do first so I guess I could just harden the whole blade as they probably won't be doing a lot of heavy chopping :rolleyes:. I would like to avoid the quench line for some future larger blades that will need the selective hardening.

One more ? How much oil should I be using to do the quenching? The blades are going to be 7-1/2" & 5-1/2" long x 1-1/4 x 1/8 (I'll only be doing one at a time). I see most folks are using 1 gallon+, but I was hoping to use a shallow pan so I could do the bottom 1/3 of the blade evenly. Anyone???
 
So long as you don't etch the O1, the line will not show very much. It's hard to see but there is a difference between the hardened and soft areas, but unless you're looking for it you won't notice it at all.

As far as how much oil, I use a small turkey baster with a billet of aluminum in the bottom to guide the depth of my blade. I use about 1/2 gallon of oil all together.
 
For small blades use at least 1 gallon of oil,two or more is better.The purpose of the quenchant is to cool the steel at a controlled rate. If there is not enough quenchant,you are heating the oil,not cooling the steel.
As to the quench line,here's what I do.Quench the whole blade.Temper once immediately at about 50 degrees lower than normal temper temperature.Lightly sand the blade to get a clean steel color.Using a hand torch,draw a temper on the ricasso and spine to a blue color.Keep the flame moving ,apply the heat sparingly, and go slow - let the temper color walk down from the spine.When the color is on the spine and only half way down the blade,quench it in oil to stop the temper.Re-temper in the oven two more times ,once at 25 degrees below normal and then at normal temper temperature.This is a differential temper.It yields a soft spine and ricasso,hard edge, great break resistance.I usually start on the end of the tang.This gets your temper color started in an area you can't mess up.Proceed down the tang to the blade and you will have the speed of the color walk down by the time you reach the ricasso and spine.Above all,avoid letting the blue color walk down near the edge.If it does,just re-harden the blade and try again.The edge will be a beautiful golden yellow color when it is done right,with a rainbow extending to the blue spine.You can harden a piece of steel bar and practice this technique.
Stacy
 
You want to hide your temper line?! Blasphemy!!! ;) And here I've spent the last 5 years figuring out how to make mine better looking and more apparent. Hmmm...
Anyway, Dave is right. On an O-1 blade, with some use that patinates/discolors the blade it'll probably show more over time, too. But, you can always sand it down again. Another option is coating the blade with something.
 
Why would you want to hide temper lines. They show knife buyers that the edge is hardened. But different strokes. Fully harden blades and temper as normal. get a baking pan and put at least 1/2 inch of water in it .place blade edge down and draw the back with a torch. I use this on damascus. :D
 
Chiro75 said:
You want to hide your temper line?! Blasphemy!!! ;)
Click to expand...
:D

Great answers. You all passed the test :p

Seriously, thanks all, I think I will do the full quench and draw the spine with a torch.

Of course more answers means more questions...

bladsmth - So, say I have heat treated the whole piece, tang and blade. Now I start with the flame on the tang (it's not a hidden tang so do I just do the spine/ top edge or the whole 'handle' ?) and work my way along to the ricasso and spine. Do I keep the "blue" just along the top of the spine or do I let it creep down 1/4 or 1/2 way to the edge? I realize I need to stop half wayish before I hit the point.

Also, a question re: the first temper. Can I let the blade cool to room temp to clean off the oil before putting it into the oven for tempering? What is the time/temp allowance before getting it to the tempering stage?

Thanks again
Nats
 
Nats, I draw a spring temper (blue) on the whole tang,thus the ricasso is all blue at the guard area.Then I angle the blue line up toward the spine and have it run down the middle of the blade. I go to about 1" before the point.Tempering immediately is more of a technical thing than a critical thing. The sooner the better,but you don't have to pull it out of the oil and throw it in the oven in one fell swoop.Just don't postpone it for a long period of time (the austentite/martensite mix is still in flux until set by temper).I just take it out of the quench tank,wipe it off, steel wool it with 2/0 wool,and pop it in the per-heated oven.
Stacy
 
remember the two ways of differential HT..

(differential edge quench) for best hamon, edge quench or use Clay
( differential tempering) for less hamon
for less and fool proof
heat and full quench the blade then temper normaly..
then draw the spine.. I use a water tube..
if you water tube the edge you don't have to worry about the edge getting too hot.
take a piece of copper tubing and split it up the center
place the edge in it forming it to the contour of the edge profile.
tighten up the gaps and partly plug the end and then run water through it.. now the edge can't over heat..you can it heat until your blue in the face.. :D
 
I believe the 'rule of thumb' is that you have up to 10 minutes from quenching the blade to get it in the tempering oven ...for ideal grain structure and to prevent stress from forming within the metal.
 
jiminy said:
I believe the 'rule of thumb' is that you have up to 10 minutes from quenching the blade to get it in the tempering oven ...for ideal grain structure and to prevent stress from forming within the metal.
Click to expand...

O1 can be left for years :D
 
Thanks again Stacy. Excellent answer.

blgoode said:
Avoiding?? Whats that? :D :D
Click to expand...
:D
I figured I would be hearing from you in this thread soon blgoode. I have been quietly admiring your knives (specificly the quench lines) for a while now. I'll have to steal your etching secret off you ;) (ferric cloride?) as i will be doing some with the line in the future.

So is this quench line called the 'Hamon'? I notice Dan had mentioned it but as I am quite new to this whole knife making thing, I'm still picking up the terminology... slowly :rolleyes: .
 
Don't want to throw any water on your hot steel boys, but it's not a temper line. It's a quench line and already established before you draw your temper on the blade. Think about it.
CRex
 
blgoode said:
need any help Nats just email me. Hammonds are fun :p
Click to expand...

I went out with one of the Hammond girls once :confused: :)
That's Hamon my boy :D :D

OK who said temper line :confused: :D

crex said:
Don't want to throw any water on your hot steel boys, but it's not a temper line. It's a quench line and already established before you draw your temper on the blade. Think about it.
CRex
Click to expand...

when you full quench then draw back by water tube
,,, that would be a temper line and it was not there first in this case...you can't see it as well but it's there..
 
I didnt recognise you Dan ;)

CRex is right. I just call it a temperline because thats what I have heard it called for so long. Time to change terms! :p
 
I think it's called a temper line not because of what creates it, but rather because it's the line between two different tempers on the blade. I could be wrong, but it makes sense to me.
 
Chiro75 said:
I think it's called a temper line not because of what creates it, but rather because it's the line between two different tempers on the blade. I could be wrong, but it makes sense to me.
Click to expand...

it depends on if you're making a temper line or a hamon :)

actually a softened spine isn't a temper, it's an annealing if you go dead soft
you could I guess call it an over temper. :) I see your point though.
you want some hardness points there , particularly with steel like 1095
you can bend that stuff with your fingers pretty easy dead soft..
 
You must log in or register to reply here.
Back
Top