[Old and Reliable]

In code welding, hydrogen embrittlement in the HAZ of the weldment can cause failure- in fabrication and structual grade steel- so preheat, post heat and use of low-hydrogen filler rods (AWS code 7018 for example) can prevent this form of weld failure-

As Damascus and twist barrels were "welded" so to speak- ie: heat and hammer blows of the twists of iron and steel over a mandrel, would trace hydrogen also play a part in latent embrittlement in these barrels?

Ductility would usually result from Mn and Si added to the steel during the BOF (or later, electric melt) furnace- but the iron strips, a different story perhaps-

I was just out shooting barn pigeons today with two of the 12 gauge Parkers- the GHE with Vulcan Steel barrels, and the PH with parker twist barrels- shot RST 2 & 3/4 dram 1 & 1/8th oz. No. 8 and Win 2 &3/4 dram lite 1 oz no. 9 shells- never have had one problem with that PH made in 1902 using those lower pressure loads, and the birds seem to crumple up in the air at my comfortable pass shooting range- no need for the more expensive HV loads at all- no recoil, easier on the wallet too-