All this talk about microstructural changes depends on the base metal. If it's plain low carbon steel, it's really not that tricky to weld repair using good overlapping seams. If you're working with HSLA steel, you'll run into the problem of brittleness in the HAZ immediately adjacent to the weld. It's extremely difficult for a welder to cool the part slow enough to avoid this phenomenn. This can be a serious problem on a loaded part.
Battleships are typically made from plain carbon steel.
Nobody can really tell just from looking if the part is plain low carbon or HSLA. The only clue may be how intricately drawn the part is. Intricately (or deeply) drawn parts are typically NOT HSLA.
95 E320 Cabriolet, 131K