Is there a learning curve on 10-- steels?

C

Cronnacht

Joined
Feb 12, 1999
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137
Or am I just wasting my time?

Almost every blade I make in a 10 series steel cracks. I've tried heating the quench water, using oil...everything short of buying a kiln to make sure that my temperatures are dead on.

Does anyone have any pointers?

At this rate, I'll be sticking to O-1. I never have an issue with O-1.
 
Are you forging or stock removing? Are you normalizing prior to hardening? How are you judging heat? What final grit are you working it up to prior to heat treating?

Common causes of cracks include forging too cold, not properly stress relieving the steel, and stress risers.

I'd definitely use a proper oil warmed a bit. Water is a tough trick for most steels, even W series.

--nathan
 
I don't know what steel you are using but 1095 has the sharpest learning curve IMHO, and you need a fast quenching oil ( ie, Parks 50) and soak at 1500 degrees for 20~25 mins before quenching.......Unless you have that ability you will have problems most likely
 
O1 needs a soak to go into solution, 1095 should not need much of anything. There is virtually nothing in 1095 that can contribute to solute drag.

I'd also like to know if you're forging or stock removing and where the 1095 is coming from. How are you controlling the heat? Are you using a magnet, going by color or trying to watch for decalescence? If it's cracking in oil, something is very wrong.
 
[/QUOTE]
I'd also like to know if you're forging or stock removing and where the 1095 is coming from. How are you controlling the heat? Are you using a magnet, going by color or trying to watch for decalescence? If it's cracking in oil, something is very wrong.[/QUOTE]

I second that. Use a magnet, and like Silver Pilate says, you may have this problem due to stress risers. It does sound odd that 1095 is behaving so poorly. Are you sure your steel is 1095 and good quality? Or was that you that posted the other day saying you had gotten it from Admiral... try rough grinding to 220 before HT, leaving no scratches from rougher grits.
Where are your blades cracking? The same place every time? Maybe your blade design has an inherent stress riser like a real sharp shoulder at the tang or somesuch.
 
I'd be willing to bet that your heat is too HOT when you quench the blade. I have in the past heated 1095 to around 1800+ (Orange) and quenched it and CRACK CRACK CRACK!
 
If you don't have an oven, or a way of controlling temp, you are wasting your time with 01 also. If you are going to continue with 1095, get some Parks #50 oil. If you go back to 01, you need an oven, or other form of heat control, so that you can soak it properly.
 
I've done forging of 1095 and stock removal. The two blades that have survived were oil quenched in standard mineral oil.

The latest blade, the one that inspired this post, was stock removal. No grinder, just file and sandpaper. The crack appeared underneath the clay that ran to the edge and continued on a curve through the hardened area of the blade. That area was fairly deformed, and looks to be the narrowest area at the edge.

As for temperature, I've had the same issue that Leu has had, and started quenching at lower temperatures (as judged by color).

Part of my theory is that I'm not leaving enough metal at the edge in the case of the blade that cracked last night.
 
Every blade that I've forged out of O-1 has survived, even with judging the temperature by the heat color. I've used mineral oil for the quench, and have not gotten a crack.

There are days when I wonder if all of this isn't some kind of metallurgical voodoo.
 
Some pictures of knives and cracks would greatly help us to understand what is the situation. What kind of forge do you use, propane, charcoal?
 
LRB is dead on with his analysis he just didn't fill in the details as to the differences in success and failure between 1095 and O1. Obviously a cracked blade is irrefutable failure, but a completely intact blade that only has .5% carbon in martensite solution is deceptive, it skates a file and it cuts, just not as long as it should. I would rather have the cracks that tell me this blade is done and I need to make a new one before sending it out of my shop than have a good looking blade that when compared to others made from O1 only cuts half as long.

All steels have a learning curve, some are steeper than others, the secret is not reinventing the wheel. These steels have been around for along time and follks much better and more equiped that any of us for heat treating them have well documented how to getr the most out of them. Each and every steel out there has this valuable information, our learning curve can be smoothed out in a hurry if we just use these available tools.
 
Cronnacht said:
Every blade that I've forged out of O-1 has survived, even with judging the temperature by the heat color. I've used mineral oil for the quench, and have not gotten a crack.

There are days when I wonder if all of this isn't some kind of metallurgical voodoo.
Click to expand...

You're on the right track. You got color and temp and quench.
You've left out the most important factor with O1, and that is TIME!
There's no voodoo involved.
Read Kevin's post.
From what I've gathered here, what is happening on your 10XX stuff is that you are getting them HARD! Perhaps, too hot and over stressing them, but now you see what you're up against when actually creating martensite!
It's just easier to create martensite with siompler steels than the complex O1 you mention.
The reason you're not having trouble with your O1 is that you're not getting full hard.
That stuff needs to soak about 20 minutes at a controlled 1500 degrees for full austenization of the steel. And THEN quenched in the right oil. If you're not doing that, you aren't bumping up against the "martensite wall"!
It's almost like saying that if you aren't getting in trouble, then you're not getting anything done.
See what I mean?
That's what Kevin is saying.
He'd rather KNOW that he stressed his steel to the point of cracking by creating full martensite than only make a little martensite, have no cracking "issues" and a knife that worked a little bit, and passed as a "success".
I know I'm saying the same thing, but in a different way.
There is NO VOODOO involved.
You just need to treat each steel the way the industry designed it.
 
Kevin when are you going to write that book? I think you will be surprised at how many you would sell. At least it would be in a language we could understand ( unless you wanted to impress the scholars).
 
There is a cheap way to tell if your getting your steel too hot, temp sticks. if you don't have an oven or salt pot. a temp stick is a cheap way to see when you hit 1500. it will help you. it helped me before I made my salt pot. and I would think you would start with 1065. it is a nice steel to start with. 1095 has a sharp curve.
 
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