Kelly Worlds Finest Heat Treat and Construction

[John Frankl]

Thought I would start a separate thread for this. Took my Kelly double out of a vinegar bath. It cleaned up nicely, and from the side shows nice even and deep hardening lines.

What really caught my eye, however, was the view from the top and bottom. I expected either a homogenous piece of steel or a mild steel body with tool steel bit forge welded into it. What the etch tells me though is that the construction is actually the exact opposite of what I expected. That is, it appears the tool steel bit was split and the mild steel body was forge welded inside it--the exact opposite of what I consider "typical" axe construction. I'm including 3 photos below, all of which show this, and the fourth photo would have been largely the same.

I have no idea. Maybe this is typical and only new to me. Or maybe it is a single piece of steel and only the surface hardened as the cross section became too thick. Any and all opinions and comments are greatly appreciated.

 

[Square_peg]

What the etch tells me though is that the construction is actually the exact opposite of what I expected. That is, it appears the tool steel bit was split and the mild steel body was forge welded inside it--the exact opposite of what I consider "typical" axe construction.

You will see these from time to time. I'm not sure why they were done this way. Probably faster in some way in a semi-automated process. Like you, I prefer to see them the other way with the mild steel split and the high carbon stuff in the middle. That way the edge stays high carbon further back into the cheeks as you wear it down.

Here's a pick done this way.

 

[John Frankl]

Thanks!

 

[Steve Tall]

The overlaid steel is called an "overcoat". Axe makers using the competing method, the inserted bit, would sometimes explain in their catalogs why the overcoat method was inferior; as I recall it had to do with the hardened steel eventually wearing away with repeated sharpenings. Here's an excerpt from Kauffman's book American Axes about "overcoating", with text from a Mann catalog which defends their use of the overcoat method, and states that the two methods had exactly the same manufacturing costs:

http://books.google.com/books?id=x5ZiYCZRdHwC&lpg=PA146&ots=1C9tevcoyO&dq=overcoat%20bit%20axe&pg=PA53#v=onepage&q=overcoat%20bit%20axe&f=false

 

[John Frankl]

Thank you, Steve. That makes everything very clear.

I agree with the Mann people. By the time I sharpen away 1.5" of hardened tool steel, the profile of the axe would make it largely useless no matter what the construction method. Still, it means that this particular Kelly predates the huge drop forging hammers and monosteel construction.

Anyone have any ideas about when Kelly stopped forge welding and went to mono steel?