In South Africa we have been metricated for as long as I can remember, yet we still use the E70XX designations when talking about American based welding. (ASME, AWS etc...)
Obviously the South African and European specifications have metricated values in their designations. So far however, these specifications have been much less user friendly than the American one's and are not used as widely as the AWS designations.
What I have been observing regarding the American specifications in the last couple of years is that they are comming out with "dual" imperial and SI units. Possibly then if you look at the electrode specs., it will show that an electrode that has a deposited filler metal strength of 70ksi or 483MPa is designated as E70XX. Judging by the speed of change to SI units in America, I doublt that they would change the whole designating to E480XX. (But then stranger things have happened.)
I know that this is not an exact answer to your question, but I recon that you might find the "outside of America" view informative for what it is worth.
Regards
Niekie Jooste
Some of the Marine Classification Societies have a different scheme for grouping electrode. Lloyds uses a system that groups (carbon steel) electrode by the following properties: Charpy temperature filler is rated for, tensile value filler is rated for. One example is: 4Y40 - the 4Y indicates the filler is rated for -40C, the 40 indicates the filler is acceptable on base metals up to grade 40 (yield strength 40 N/mm2 divided by 10).
There is a comprehensive chart on the approved welding comsumables chart Lloyds Register has posted on their web site.
It may be that the other classification societies also use the same scheme. There is a group known as the IACS (International Association of Classification Societies), that was formed to gather the construction/maintenance activieties (for Marine Projects) under one set of rules recognized by all classification societies. This eliminates the need for a company that is fully compliant with one society's rules (maybe ABS) from having to become fully compliant with another society's rules (say Lloyds Register) in order to perform work that is governed by the second classification society.
When you get into this arena, be prepared for some confusing times...Charles Hall