Trying my hand at knifemaking and having some problems...

onenotsaved

onenotsaved

Joined
Feb 5, 2009
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Hello, all.

I've been lurking on this site for well over a year now and have gleaned a load of information. So, first of all, I would like to thank all seasoned bladesmiths out there for sharing their skills and wisdom.

Okay. This is my second attempt at a knife. My first cracked during the quench, but I immediately realized my mistakes...or, well, I had hoped.
This knife, however, snapped while I was attempting to straighten a warp.
The steel is 1095. The overall design is a kwaiken kind of deal at 1/8" by 1" by 9", half blade and half handle. The hardening went fine except for a slight warp just past the ricasso, blade-side. It bent maybe 1/8".
Also, if this helps, I used a makeshift forge, charcoal, and plain water. I tested the edge with a file and it skated like it should all along the edge. I did some rough grinding on it with a belt grinder but most of the shaping was done by filing, so I doubt I overheated the steel beforehand.

Tonight I did two tempering cycles at 450 degrees for an hour each, first laying the blade on one side and then the other. After the tempering I tested the flex by pressuring the blade slightly with my thumbs...like you would go to snap a twig, you know? The blade flexed a bit and returned back just fine.
So I prepped a small vise, inserted the blade right on the warp point, and using very little leverage I barely pressured the warp, bending the blade just short of straight when it snapped.

I realized this could have been a defect in the steel, thought that's not likely as my techniques are still pretty sloppy. The only thing I could think of with my limited knowledge on heat treatment is that when the blade warped microscopic stress fractures formed.

If you all can think of anything to help me out here it would be immensely appreciated. So, thanks in advance to all of you!


Take care!
Joe
 
The problem is that you quenched in water. Use warm oil next time and read the "stickies" at the top of the page, they will tell you everything you need to know.
 
1095 and water is indeed tricky as Louis has pointed out. However, after two tempers at 450, it probably shouldn't have been that brittle. So, you've got two problems to figure out before your next attempt:

  1. Why did it crack?
  2. How do you safely deal with warpage in case it happens again?

As for the why it cracked, it's hard to tell from just your description. Could you describe the interior of the break for us? Was it clean and uniform in color, or was there some areas darker that others? This might indicate a crack that occurred during the quench. Does it look like sand or like a smooth, milky surface? What we're looking for here is whether or not you can see the crystalline structure of the grain colony boundaries with the naked eye. If you can, you likely overheated the blade. If not, we need to keep looking a little bit.

On to the "how to deal with warping" bit. From the sound of it, you were trying to straighten it cold. This will pretty much never work with a hypereutectoid steel like 1095. The best time to straighten any warpage is immediately after the quench, but before the blade has come down to 400F or lower. The reason for this is that the formation of the structure called martensite (the "hard stuff" that we all shoot for) doesn't actually form in the blade until about 400F. The reason for the rapid quench is to get the steel rapidly below a certain heat (that varies some by steel) where a softer structure that we don't want called pearlite can form. For 1095 this is about 1000F. So, you've got roughly a 600 degree window to straighten in. What I do is keep a set of welding gloves handy (on my hands...) while I quench. I enter the quench for 3-4 seconds, pull the blade out and look for warping. If it's there, I grab the (still very hot) blade with my gloved hands and straighten it. Then, back into the oil to finish cooling.

I second Louis' suggestion to re-read the stickies up top, especially Kevin's Working the three steel types since you're working with 1095.

-d
 
Ditto Rob and Louis.

Another important thing, especially with hypereutectoid steel, is to normalize the steel prior to quench. The grain structure and internal stresses need to be made right before you permanently harden the blade. Read the stickies on "Working with three steels". Kevin has explained it quite well there.

That said, 1095 is not the best starter steel. 1084 or something in the eutectoid area would be far better. Even the pros occasionally snap a 1095 blade, and warpage is a common problem with it.
 
bladsmth said:
Even the pros occasionally snap a 1095 blade, and warpage is a common problem with it.
Click to expand...

Using water it's well more than occasionally too ;) Many of the professional folks I know who water quench 1095 (or really any 10xx simple steel) pretty much lose 50% of what they do unless they have REALLY pared down the variables and gotten consistent with it. Then it's only about 33% :D

-d
 
also if you have a pit or a scratch that will act as a notch for fracture propagation. Everything you have been told is great advice, read the stickies! 1095 is not beginner steel

-Page
 
Joe,

Where are you in Kentucky? I'm in Evansville, Indiana. You are welcome to come to my shop and see how I straighten blades, we just need to agree upon a time if your interested.

When hardening I do an interupted quench, holding in oil till the oil just stops boiling off when removed, oil boils arround 500 degs. Then I staighten by hand wearing welding gloves or using a vice. You should have 30 seconds to a minute to work the blade before it starts stiffening up then stop.

If it requires tweaking after that I tweak it at the end of a tempering cycle while the blade is up to temp I pull it from the oven and tweak it and go right back in the oven to finish the tempering cycle. I never try to straighten a cold blade, at minimum I would put a torch to the spine and draw a blue temper on the spine and try to staighten while hot but don't let the color run to the edge.

Steve Seib
 
Thank you all for your responses. This information so far has helped me quite a bit. So, back to researching and studying! Luckily, I'm a quick study, so we shall see how the next project goes.

Now, onto individual responses...

rocketmann:
I've heard the horror stories around straight water and 1095. My first project cracked in a brine quench, so I decided to do straight water this time. I had canola oil ready to go...but I figured I'd try my luck.

deker:
Ohhhhh....okay.
It's a pretty clean break, but there are two colors. The spine and the edge are a copper color with a dull silver in the middle. And it's sandy, not smooth. I was afraid I had overheated it after the quench...
And, you know, I had that thought right after it snapped.....why did I try and do this cold? At the very least I should have tried straight out of the temper rather than letting it cool.
I forgot to mention that I had done an interrupted quench. I looked for warping during the interrupt but it was pretty dark out by that time.

bladsmth:
I see...I actually did know about that but elected not to do so. I had read arguments both ways and figured I'd go at it as simply as possible until I couldn't anymore.
And why can't the easier steels be as cheap as 1095? ;)
You suggest 1084...please elaborate on how it's different. I really don't know in-depth stuff about steel types. I understand their basic respective makeups and what does what for it...but I suppose I need to look up what "hypereutectoid" means.

sunshadow:
And actually there was a bit of a scratch, though not where the warp happened. While filing I kind of got into it and forgot to clean the file...and, yeah...sanding took it down to barely noticeable, but, man, being anal sucks when it comes to stuff like this. :D

steve:
I'm in Pikeville...pretty much all the way east. I'm hardly ever that way but thanks for the invitation. I may take you up on that!
And thanks for the information. That's stuff I'll need to keep in mind.


Thanks, all, so much again for the help!
Out of curiosity, can this steel be saved? Since it looks like I overheated it, can this now be annealed?


Take care, all.
Joe
 
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bladsmth said:
Ditto Rob and Louis.

Another important thing, especially with hypereutectoid steel, is to normalize the steel prior to quench. The grain structure and internal stresses need to be made right before you permanently harden the blade. Read the stickies on "Working with three steels". Kevin has explained it quite well there.

That said, 1095 is not the best starter steel. 1084 or something in the eutectoid area would be far better. Even the pros occasionally snap a 1095 blade, and warpage is a common problem with it.
Click to expand...


The answer is there.

1084 is the eutectoid. No steel will be simpler to work with.
 
bladsmth said:
The answer is there.

1084 is the eutectoid. No steel will be simpler to work with.
Click to expand...

Okay. Yeah, I've been reading since I asked that and I see it now.
Thanks again! :D


And upon reading a bit further I'm excited to learn that 1075 is close enough to the ideal range (i.e. 1084) that it would be suitable for me. I'm glad I picked up a bar of it on a whim in my last order.
I have to admit I was getting disheartened by the second failure. But I'm glad to learn that I'm making common beginner mistakes...you see, I have this problem with patience.
Well, back to the grinder!

Thanks again, everyone, especially for the patience as I'm sure you've seen my same questions asked so many times.
Hopefully one day I'll be in your shoes helping you all put up with ignorant beginners like me! ;)


Take care, all!
Joe
 
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