Multiple Temper Lines

D

Daniel Krohn

Joined
Nov 23, 2004
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I recently heat treated a batch of four butcher knives out of 1/8" 1095. When I etched them they had multiple temper lines, some long, some short, and some that would just dead end. Is this a problem, what causes it, and how do I avoid it?
Daniel
 
Have any pictures ?

1095 can be tricky. I still dont understand why it seems to be the suggested material of choice for new makers.
 
I have a knife made from 10xx (can't remember which :o) that has multiple quench lines. I kinda like it, actually. :D

My father-in-law did the HT on it actually....he stuck it in once, pulled it out, stuck it in again, but slightly deeper. I tested it for hardness and both areas would skate the file.

Do you have pics? I'll try and get a pic of mine.
 
It looks like the tip decarbed, only reason I say that , is the rest of the hardened zone is so nice and even. So the tip should have gotten hard with the rest of it..

How long did you hold it above non magnetic?

Dunk it back in the etch for 5 minutes and just rinse it. If that area at the tip doesnt turn black like the rest of the zone, it's probably soft.
 
I'd redo the tip as Mark said. Personally I like 1095 and use that and 1084 alot. Holds a good edge and sharpens easily. The multi-temper line thing can be alot of fun. If your careful you can almost get a fan pattern in your blade.
 
mark, i believe its the suggested choice because it's cheaper than anything else, and it's better to make your mistakes on it than the higher priced steel.once i got my ht together with it, i enjoy using it.just my opinion
 
Did you quench it tip first? Did you hesitate a bit? Looks like a quench line to me.

Oh yeah is the dang thing hard? :)
 
I used nothing but 1084 for years and recently switched to 1095 based on the advice that they're basically the same thing and I agree with Mark. 1095 takes a lot more work to get right than 1084. Is O1 still the best newbie steel? I should try some just to compare....
 
In HT I think I quenched as soon as it hit nonmagnetic or soon after. The quench was tip first and then rocked to get the whole edge. the funny thing is that my thicker blades don't have this problem. Right after quench I did the file test and it passed but I have not done the brass rod test.
Daniel
 
If I remember right, 1095 has a lot narrower window than 1084 for the quench, meaning as soon as you get it to temp, quench. 1084 gives you a couple seconds to get to the quench.

Just a quess, but looks like when you went tip first then rocked it the tip came out of the quench? If so part of the tip probably fell below the harding temp causing the double temper line there. Just my guess. I played around with the tip first, wait, rest of the edge, then back to the tip and so forth quench, but for most I now just quench tip first and hold till it stops glowing, harding a bit more than half the blade, with the harding line highest at the front and narrowest at the ricasso.
 
True, quench right away. I've never been completely comfortable with the "rocking" method. I just stick it in making sure the tip and plunges are in far enough. This gives me a straight temper line going diagonally up the blade.
 
Will52100 said:
If I remember right, 1095 has a lot narrower window than 1084 for the quench, meaning as soon as you get it to temp, quench. 1084 gives you a couple seconds to" get to" the quench.

Just a quess, but looks like when you went tip first then rocked it the tip came out of the quench? If so part of the tip probably fell below the harding temp causing the double temper line there. Just my guess. I played around with the tip first, wait, rest of the edge, then back to the tip and so forth quench, but for most I now just quench tip first and hold till it stops glowing, harding a bit more than half the blade, with the harding line highest at the front and narrowest at the ricasso.
Click to expand...
I was under the impression that quenching speed, a.k.a. making the gate, has nothing to do with how long the steel is held at critical temp or how long it takes you to get from the heat source to the quench, as long as the steel stays above critical, but involves the time it takes for the steel to cool from critical to gate temperature which is around 1100 degrees or so for 1095.
 
I heat-treated 6 blades end of last week, 3 were 1095, 3 were 1084. I couldn't tell the difference between them. My technique was more of a factor than the steel. They all quenched fine and passed the file test. The hamon line, on the other hand, is the big distinguisher between the two. Pops out a little more on the 1084 blades.

Vid: (sanded to 400 grit, no etch)
http://www.kosterknives.com/uploads/hamonvid.wmv
 
What I'm refering the time it takes to get the steel below 400(if I remember the temp right) deg.F for complete transformation. You've got a little longer with 1084 and some other steels. When you stick the blade in the quench it isn't just cooling the submerged part, but is pulling heat from the rest of the blade as well. I'm not saying it can't be done with a rocking motion, but I've gotten more consistant results doing it like J. Neilson does, a straight quench line. If your timing is off with rocking it it's very posible part of the blade will not fully harden because it has gotten to cool. You could heat well above the transformation temp, but then you get grain growth and loose strength and performance. Idealy you want to quench right at or just a Little above transformation temp for maximum performance.
 
Yes, Will - and thanks for the kind words.
 
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