Seamless tubes type EN 1.4404 produced by hot extrusion have been internally electropolished at a mill
that normally produces such tubes from welded tubes made from rolled plate. One or two standard
passes have been applied. The short-range surface irregularities are removed by the electropolish, but the
long-range waviness, and with that also the Ra value, remains unaffected by the electropolishing. The
pitting resistance was evaluated by measurement of pitting potentials in solutions containing 500, 5000,
and 50.000 mg/L chloride and temperatures from 10 to 95°C and by the ASTM G150 test. The asextruded
and the once electropolished surfaces have pitting resistance very close to that observed with a
rolled and pickled surface. The twice electropolished surface mostly have a much improved pitting
resistance, but a few of the test results are no better than the parent material; this is discussed in terms of
the number of pit initiation sites.