If it is cast steel there is no forge welding involved in the process.

Though that distinct line you see is common to better cast steel products from late 19th ca foundries, and it is often mistaken for a forge weld.

It is however, just a tempering line.

Some good info here - http://www.threeplanes.net/toolsteel.html

I'd just be guessing if I suggested which decade this one was made.

"We build too many walls and not enough bridges" - Isaac Newton

http://bridgewright.wordpress.com/