Austin:
1. Pattern welded barrels were fabricated with wrought iron and very low carbon steel
2. As a result of the process using high heat and pressure, it was the opinion of the metallurgist at METL that the resultant product became essentially a mono-metal.
20X photomicrograph after etching with 3% Nital solution showing the bands (alternees) and a crack probably within a steel alternee, but possibly at an iron-steel interface.
The parallel lines inferiorly may be related to shear forces during the rolling and hammer welding manufacturing process.
The globular inclusions are predominantly within the grey etched steel alternees.
The non-metallic inclusions are composed predominantly of silicon, phosphorus, and sulfur. Obviously, the 'cleaner' the iron and steel, the stronger.
3. The pattern is a result of how the lopin is 'stacked' and the rod twisted
Top: Star or Etoile’
Left: Double 81 Bernard
Middle: Extra-Fine Crolle
Right: Washington or "American Flag"
4. IMHO the pattern does not determine the strength of the tube. BUT if someone would like to cut about 3" of the nice Bernard II barrel on a C grade
I'll run it over to METL for tensile testing
Wernher von Braun “One test result is worth one thousand expert opinions.”