....the gen-u-wine Metallurgical Engineer said this
"The Energy Dispersive X-ray Spectroscopy (EDX) study suggests that element migration between the metals occurred during the manufacturing process; the pressure rolling, twisting, and hammer welding of iron and steel laminates produced essentially a mono-metal."
I believe, generically, it takes time and temperature for carbon to flow from higher to lower concentration areas. Could be there wasn't enough heat or time for that to happen between the steel and wrought, but chances are at and near welds, the carbon has 'evened out'. Maybe, when some barrels color welds bright, and others color dark, the cause of the coloring is some element or elements that are not able to, or slow to migrate, rather than just the difference of being an iron or steel. Maybe.
