....It appears that the crack runs through a giant such inclusion, and that the area shown southwest of the crack where the inclusions line up would be another potential failure point.
I think we need to get it out of our heads that Damascus is 'steel'. It ain't. It's a composite structure. Even 'pattern welded steel' isn't a great description.
Just another quick take Shotgunjones. Maybe that gray area at the start of the crack is not carbon, it doesn't seem to etch the same. I'd wonder if the acid prep dissolves iron oxide, possibly a tiny pit, but not likely the origin of the crack.
The xray, micrograph and modern blacksmithing, I think show pattern welding to be more of a mono steel than series of connections. If this sample is a steel, in all likelyhood the carbon has migrated and evened out through the piece. The color differences may be other alloying elements besides iron and carbon.
A row of tiny carbon inclusions may not be a big concern. If this is a crolle pattern, that line may actually spiral through the material and may not be sitting as a sort of perforation line in the barrel. Just thoughts.
