Hatchet Hardening

[zatch]

Have a question on a recent hatchet I picked up...

I don't know much when it comes to the hardening or quenching process on axes. I picked up a little hatchet recently - unknown brand but seemed good. I cleaned it up and started sharpening it. As I was filing (there were some nice nicks in the edge), I noticed that of all the axes I've done up until now, this is by far the hardest edge I have ever worked on. I spent hours on this little guy and I have still have some spots that need to be worked out. I'm not worried about that but it did get me a bit curious.

Here it is after a clean up and sharpening...besides the filing, the sharpening process (sandpaper, convex) wasn't too bad at all.

Usually after a dunk in some vinegar, the edge turns black revealing the portion of hardened metal. I understand that much. However, after submerging this one for just a couple of hours, I got this. This after a quick water rinse and scrubbing.

In my experience, some less quality axes didn't have such a nice, distinct hamon line - the metal ended up being too soft as well. It seems as if this one was hardened properly and then double hardened? After sharpening, it took a really, really nice edge. Slices paper and arm hair with ease. I would doubt it, but would sharpening it up before a vinegar bath (while somewhat pointless ) cause that look?

I haven't been able to find an answer quite yet (I've come up with the terms "differentially hardened" and "double tempered" but I don't know if those would be correct), so any information you guys have would be appreciated!

 

[zatch]

Ok after some more reading, differentially hardended would be the correct term, or at least possible. If this is the case, that would explain why this hatchet was so hard to file. Would this be done to reduce the risk of fracture of a large portion of the steel?

 

[Square_peg]

I think what you're seeing there is the first line, closest to the edge, is the beginning of a high carbon bit. The second line further from the edge indicates the depth of the quench.

 

[zatch]

Ah. So would there be a secondary hardness level right at the edge, or is the whole bit most likely close to the same hardness range?

Thanks for the response btw.

 

[Holmesmade]

The first line would be the high carbon steel core being exposed through the lower carbon steel body of the axe. The second line is the depth of the quench.

The two different types of steel were welded together when the axe was built. The core steel is one hardness, the body is lower carbon and has a different hardness due to the lower carbon content. The poll of the axe may be even softer due to not being quenched at all, or quenched somewhat later than the rest of the body.

 

[markv]

inexpensive Chinese head , i have one just like it. so be it, hard steel makes for a nice little chopper no mystery

buzz

 

[zatch]

inexpensive Chinese head , i have one just like it. so be it, hard steel makes for a nice little chopper no mystery

buzz

I figured as much but I havent seen anything like that out of a vinegar bath. The cheap stuff I usually see is too soft rather than very hard. Thanks for the response!

 

[nickzdon]

My best GUESS (emphasis on that word) is that this not a two-piece head. It's most likely forged from a single piece of steel. The time and labor involved with making two piece steel axes is not efficient enough for most, if any, large manufacturers. I'm willing to bet that's the case even in China (especially in China). If anyone knows of any contemporary manufacturers (within the past 50 years) making production two piece axes I'd be interested in that info.

Take a look from the top down, or the bottom up, and you should be able to tell pretty quickly if it's a two piece with steel core. There should be some very distinctive lines between the two types of steel. I've got one laying around somewhere. I'll snap a pic and upload to this thread.

The line near the bit is probably the transition between the original milled steel texture, and the smoother sharpened texture you applied. The line further back is the hardened hamon line, and it's a good lookin one too. Nice and crisp and deep. I've seen dual hamons that overlap one another, and some that are spaced further apart. But the ones I've seen on cheaper import axes often are not as straight or crisp as this one.

My ¢.02

 

[nickzdon]

Here's a shot of the bottom of an old multi-piece head I have. Some are harder to see than others, but this one shows the weld seam pretty well.

 

[leebrewer]

Cold Steel Tomahawks do the same thing.

 

[zatch]

My best GUESS (emphasis on that word) is that this not a two-piece head. It's most likely forged from a single piece of steel. The time and labor involved with making two piece steel axes is not efficient enough for most, if any, large manufacturers. I'm willing to bet that's the case even in China (especially in China). If anyone knows of any contemporary manufacturers (within the past 50 years) making production two piece axes I'd be interested in that info.

Take a look from the top down, or the bottom up, and you should be able to tell pretty quickly if it's a two piece with steel core. There should be some very distinctive lines between the two types of steel. I've got one laying around somewhere. I'll snap a pic and upload to this thread.

The line near the bit is probably the transition between the original milled steel texture, and the smoother sharpened texture you applied. The line further back is the hardened hamon line, and it's a good lookin one too. Nice and crisp and deep. I've seen dual hamons that overlap one another, and some that are spaced further apart. But the ones I've seen on cheaper import axes often are not as straight or crisp as this one.

My ¢.02

I'll check that out when I get back home. When your (we) are talking about a two piece head, are we talking about something similar to what's seen here

[video=youtube;RCYAkGxL_no]http://www.youtube.com/watch?v=RCYAkGxL_no[/video]

13:30 in the video...

I doubt it's a two piece head as well but I'll check when I get home. I would think that you would only find that currently in custom pieces just because of the time/labor factor. The only reason I wouldn't think that the secondary line was from sharpening is because of the way it wraps around the top of the bit (goes farther back on the bit than where I sharpened it).

Thanks for the response and info!

 

[zatch]

Here's a shot of the bottom of an old multi-piece head I have. Some are harder to see than others, but this one shows the weld seam pretty well.

That's very distinct to me. Now that I look at it, this seems different than the process outlined in the video. Is this one have a bit that was welded to the outside, or around the head (rather than inside the head in the video)? That's pretty cool!

 

[nickzdon]

What's shown in the video is more common in custom hand made axes and hatchets today. It's the old ooollllllddddd, way of doing it by hand. What I'm showing in my photo is steel bits applied to the outside of a casted head/poll (I'm fairly certain), rather than inserted into the head. I may have been a little lax in my application of two-piece vs multi-piece terminology, which may have caused confusion.

Here's a patent showing Kelly's patent for casting axe heads that would then take hardened bits (the patent refers to these bitless heads as 'polls') This is the construction method I'm assuming the axe I show above is the product of. I'm not 100% certain that it's a cast poll, could be forged. I'm still investigating that.

 

[M3mphis]

My best GUESS (emphasis on that word) is that this not a two-piece head. It's most likely forged from a single piece of steel. The time and labor involved with making two piece steel axes is not efficient enough for most, if any, large manufacturers. I'm willing to bet that's the case even in China (especially in China). If anyone knows of any contemporary manufacturers (within the past 50 years) making production two piece axes I'd be interested in that info.

Take a look from the top down, or the bottom up, and you should be able to tell pretty quickly if it's a two piece with steel core. There should be some very distinctive lines between the two types of steel. I've got one laying around somewhere. I'll snap a pic and upload to this thread.

The line near the bit is probably the transition between the original milled steel texture, and the smoother sharpened texture you applied. The line further back is the hardened hamon line, and it's a good lookin one too. Nice and crisp and deep. I've seen dual hamons that overlap one another, and some that are spaced further apart. But the ones I've seen on cheaper import axes often are not as straight or crisp as this one.

My ¢.02

I agree with Nick.

One thing to note:

We use the word "hamon" to describe heat treat lines in the axe forum. That is technically incorrect. A hamon is a heat treat line created by the ancient japanese technique of differential hardening using clay to slow the cooling of the part of the steel intended to be softer and more springy than the hard edge.

Just a technicality, not a biggie.

 

[nickzdon]

We use the word "hamon" to describe heat treat lines in the axe forum. That is technically incorrect. A hamon is a heat treat line created by the ancient japanese technique of differential hardening using clay to slow the cooling of the part of the steel intended to be softer and more springy than the hard edge.

Just a technicality, not a biggie.

To wit, we shall now refer to them as Memphis Lines!

 

[Square_peg]

Here's a shot of the bottom of an old multi-piece head I have. Some are harder to see than others, but this one shows the weld seam pretty well.

Sometimes the softer head metal is split and a high carbon bit is forge welded in, resulting in a slight different look.

This method results in high carbon steel in the center of the tool (cutting edge) for a greater length.

 

[nickzdon]

Sometimes the softer head metal is split and a high carbon bit is forge welded in, resulting in a slight different look.

This method results in high carbon steel in the center of the tool (cutting edge) for a greater length.

What is that there Square? Got a manufacturer name or a rough date on it?

 

[nickzdon]

Zatch,

One other way to find hamon/memphis lines is to buff to a high polish. You'll have to buff a significant portion of the bit to contrast it, but in the right light the line should really pop.

 

[Square_peg]

What is that there Square? Got a manufacturer name or a rough date on it?

It's an old pick, likely from this areas earlier coal mining days (1890-1920). No makers mark or date on it. It's a big beefy sucker, though. Both bits are forge welded like this. I don't know whether this is the original manufacturing or a later blacksmith repair. I spoke with an old smith who said that such repairs were commonplace back in the day and that he had made such repairs himself many years ago.

In any case it's a mighty fine pick - my current favorite. I re-forged that tip. It was rounded over when I got it. Made more sense to sharpen it with fire than to leave filings on the floor.

 

[zatch]

Zatch,

One other way to find hamon/memphis lines is to buff to a high polish. You'll have to buff a significant portion of the bit to contrast it, but in the right light the line should really pop.

Did not know that! Can I polish it as it is or do I need to bring the whole bit up to a certain grit level first (like 800-2000)?

The one I have, as I figured, is all one piece. That's a sweet picture Square_peg!