I was using the 8018-B6 classification a little bit too loosely, I should have been saying 80XX-B6 as AWS A5.4 does not have a -18 classification. But there haven't been any changes in electrode naming conventions recently. Thanks for pointing out the strength diffenece though, I hadn't noticed that before. But I do think you can substitute 80XX-B6 for any application for which E502-xx was previously used. AWS A5.5 says "The E8015-B6 and E8015-B6L electrodes were formerly classified as E502-15 in AWS A5.4-81, Specification for Covered Corrosion-Resisting Chromium and Chromium Nickel Steel Welding Electrodes. The E8016-B6 and E8016-B6L were formerly classified as E502-16 in A5.4-81. The 8018-B6 and E8018-B6L were not formerly classified but were produced to the E502 composition ranges in A5.4-81 but with the EXX18 covering of this specification."