Troubleshooting a string of fails

J

Jonathan BRG

Joined
Oct 11, 2019
Messages
38
Hey everyone….
Been a member for a little bit, I don’t post, but I basically learned what little I know from pouring through these threads. (Thanks)

I’ll do my best to be brief, but I have a situation that is very frustrating.

I haven’t made a knife since the end of July, and I just got the itch to get back in the shop, but something is screwed up.
I thought I had everything dialed in, and was churning out some decent knives…..till the I tried two this week.

I had refined my single bevel gyotu shape and geometry to where I thought I finally had my signature knife, but somehow I lost temper on it, and after repeating all my steps more carefully, it happened again today!
I’ve been making blacked out knives lately, and the ferric dip told the story. Blotchy, very light sections, all the way to the cutting edge.

Both W2, first was a hamon, so I figured I put too much fireplace mortar on the spine, and that somehow messed up my quench, even though I’ve done it the same way 5 or 6 times with no issue.

Second knife …..no hamon, paid extra close attention to every step…..same result.
Except, I dipped after HT and temper , and it was perfect.
After grinding, before hand work….same mess as the previous one.

I’ve ruined temper during grinding, when I was learning, mostly because I take my blades really thin, and to basically sharp. (I hate sharpening on stones, so I try to keep it to a minimum.)
I don’t think that’s the issue. I feel like I’d know, and I was triply careful on the second one.

I do my HT in an Evenheat LB27
Quench in Parks 50 (heated to around 80-95 since it’s cold in my shop)
I run a mister and a platen chiller on my KMG-TX.
I use fresh Combat Abrasives belts.
I test with hardness files.
Even changed out the ferric solution in my tank today just in case.

Something is screwed up, and I don’t want to waste more time, metal, belts, and pure pissed off-ness before I figure it out.

Any ideas on what is going on?
Sorry for the long post, but I wanted to give as much info as possible.
Thanks in advance,
Jonathan
 
Drew Riley said:
Got any pictures?
Click to expand...
Of the two fails….?
I didn’t take any after ferric. I just sat and cried 🤣….and hoped it was a decarb thing (even though I knew it wasn’t).

Lemme see if I can post some pics.

And…..thanks….I know it’s a goose chase question for the most part, so I appreciate your response.
 
Those look really good - do you make the San Mai (Go Mai) with nickel between layers to get that nice shiny line?
 
Ken H> said:
Those look really good - do you make the San Mai (Go Mai) with nickel between layers to get that nice shiny line?
Click to expand...
Thank you.

No….I don’t. I’m a purely stock removal guy at this point, except for a little heating and hammering on that Aogami above.

I get it from Dion Damascus.
I love their steel, and they are great guys to do business with.
 
Is there any chance that something is wrong with the bar of W2 that I got?
Both blades were from the same bar.

Is that even possible?
It’s the only variable I can think of.
 
I am pretty sure the only W2 available comes from NJSB. Other suppliers that sell W2 get it from them, at least that's what I was told. Since Jonathan BRG said he is purely a stock removal guy, then I can almost guarantee the problem is the coarse spheroidized structure of that W2 as received from the mill in Europe. It's been years since I've used that W2, but I have heard that it takes an abnormally high normalizing heat to get that carbon ready. That's why forging guys aren't noticing the problem. Try normalizing at 1900°F, maybe again at the regular normalizing temp of 1650°F. Maybe cycle it at 1500°F and then go to hardening.
 
Stuart Davenport Knives said:
I am pretty sure the only W2 available comes from NJSB. Other suppliers that sell W2 get it from them, at least that's what I was told. Since Jonathan BRG said he is purely a stock removal guy, then I can almost guarantee the problem is the coarse spheroidized structure of that W2 as received from the mill in Europe. It's been years since I've used that W2, but I have heard that it takes an abnormally high normalizing heat to get that carbon ready. That's why forging guys aren't noticing the problem. Try normalizing at 1900°F, maybe again at the regular normalizing temp of 1650°F. Maybe cycle it at 1500°F and then go to hardening.
Click to expand...
That's where I was going with the question, you beat me to it!
 
Stuart Davenport Knives said:
I am pretty sure the only W2 available comes from NJSB. Other suppliers that sell W2 get it from them, at least that's what I was told. Since Jonathan BRG said he is purely a stock removal guy, then I can almost guarantee the problem is the coarse spheroidized structure of that W2 as received from the mill in Europe. It's been years since I've used that W2, but I have heard that it takes an abnormally high normalizing heat to get that carbon ready. That's why forging guys aren't noticing the problem. Try normalizing at 1900°F, maybe again at the regular normalizing temp of 1650°F. Maybe cycle it at 1500°F and then go to hardening.
Click to expand...

That is the thing I was worried about.
I have been getting away without thermal cycling because I assumed the billets came to me ready to heat treat.

I normalize the bars I get from Dion Damascus because I’ve noticed it helps to mitigate warping upon quench, but I rarely normalize, and hardly ever cycle my Alpha Knife Supply stock , and haven’t had any issues (that I can detect) because of it…….until now.

I use a few of my knives daily, and they perform exceptionally.
Just gifted a nice hamoned W2, that is spot on.
I’m confused because I’ve had success with it before.

Maybe I need to start being more patient, and running everything through 5 cycles of heat treatment.

Can’t thank you enough for the help.
 
How thick where the knives before hardening? I make stock removal knives out of NJSB W2 and have not had to do any high heat cycles to get it to harden. All I do is a stress relief cycle at 1350 for 15 minutes after all of the grinding is done and the blades are ready to harden. If your material is too thick before hardening you can grind through all of your hardened steel since W2 is very shallow hardening. I take my edge to .04-.05 pre heat treat and bring the grind up 90% to the spine in most cases.
 
Just to clarify, I am not saying for certain that is your issue, Jonathan, but it sure has the hallmarks of the coarse spheroidized structure. It may be your bar is from that batch, I just don't know. It could be a variation in quench medium temperature or agitation/vapor jacket. Hard to say exactly. I recall knife maker's saying that one half of a bar would harden OK, and the other wouldn't. I wouldn't worry about doing a whole lot of cycling. W2 has that 0.2% vanadium and goes a long way in keeping grain size small, even at very high heats. If it happens again, try normalizing it once at 1900°F and then one cycle at 1500°F, then harden it with room temp P50 and make sure you give it good agitation. Just remember not to swirl the blade or go side to side, but just up/down or in/out sort of motion, or cutting into the oil, so to speak. I have heard that a thin wash of satanite, or even ATP641 antiscale compound will slightly speed up a quench by breaking up the vapor jacket.

Joshua, 1350°F for 15 minutes is in the spheroidizing range. 1200°F would be sufficient for stress relief. Your pre heat treat grinding protocol is great. These shallow hardening steels can be very finicky.
 
You must log in or register to reply here.
Back
Top