Interesting that Krupp was not included in the 1891 Birmingham Proof House Report.
Period reports of tensile strength:
Siemens Open Hearth 26-28 long tons = 58,000-62,700 psi
Whitworth 29.5-30 long tons = 66,000-67,200 psi
Krupp Open Hearth - 70,000 - 80,000
Krupp Nickel Steel was developed about 1890 - 92,500
http://books.google.com/books?id=n6NPAAAAMAAJ&pg=PA199&lpg