I thought at first when I discovered the stamp 'cast steel' that the line must be a tempering line, but closer examination tells me this isn't so. Unfortunately I can't get a good enough picture to show you what I am talking about. There are, however, lines along it where there was maybe minimal scale inclusion or somehow the weld didn't form perfectly over a tiny area (not big enough to be of any concern) -this is common on forge welding, it's very difficult to get every weld perfect. these 'shadow lines' tell me that this is in fact a weld line. Along with this, the shapes of the line is more consistent with a weld line than a temper line. Also, there was a little bit of rust on the tool when I got it and a small degree of pitting, yet this pitting suddenly stops when it reaches the shadow line , leading me to believe that the bit is made of an entirely different piece of steel than the body. Add to that that the steel on the bit is incredibly tough, hard o sharpen yet hols a keen age even while chopping through hardwood knots
I do know a thing or two about metallurgy and blacksmithing, I have messed around with it a time or two and hope some day to be able to produce my own tools. The shape, color contrast, and grain pattern in the steel (yes, steel has a grain pattern) tells me that this is a weld line and not a tempering line. My thought then was that the basic shape of the broad axe was cast, or made of 'cast steel' which is a certain grade of steel (a now obsolete designation) the same as 'cast iron' refers to a specific carbon range of steel, and not necessarily the fact that it was cast.
My theory? IT was made of crucible steel, which was sometimes referred to as 'cast steel' because it had to be cast into some form or another when it was produced (the crucible part in the name is because it was produced as molten steel in a crucible) This 'cast steel' was itself either cast, wrought, or cut out of sheet to form the desired shape, which then had a harder tool steel bit welded onto it. There are some features of the body of the head that would lead me to believe that it is a sand casting
I am not concerned about a specific decade, really all I would like to know is a general range, like 'mid 1800's' or late 1800's' or some such
