Craig: At the time of the burst, the barrel segment flew into some brush next to the shooter and could not be recovered. It would have been helpful to examine the burst edges (and probably would have saved having to section the barrel, which was a challenge), and maybe the presumed inclusion at the initiation point would still be present.
Slag is easily identified by EDX.
This is from the previously published Remington burst; a barrel section at 50X. The composition of the inclusions by EDX was predominantly silica, metal oxides, phosphorus, and sulfur ie. slag, and not manganese sulfide.
This is a section of a L.C. Twist barrel that broke when on the extensometer way back in the pattern welded barrel strength study. It broke at this inclusion which by EDX was slag
The barrel survived 110 years of use with the defective braze and "burned" steel. Interesting to speculate if it would have remained intact with "better" barrel steel (it is non-standard AISI 1018 low alloy low carbon steel with slightly high phosphorus & sulphur, and a low concentration of nickel) and/or without the presumed inclusion and/or the high pressure reload?
