Microstructures of ion‐implanted 18Cr8Ni steel surfaces were examined using a metallographic approach, i.e. etching and optical microscopy. Polished surfaces were implanted with selected ions (Ti+, N+, Ar+, Ne+) to high doses (≳1017/cm2), then Ar‐ion milled stepwise to beyond the implantation depth. Michelson interferograms showed that the implantedsurfaces were eroded at the same rate as nonimplanted surfaces. Average erosion rates were 0.17±0.02 and 0.02 nm/μA‐min/cm2 for 1 and 2 keV Ar‐ion bombardment. Several implantedsurfaces, nonetheless, developed unique etch features. On most surfaces, large (50–100 μm) austenitic grains became visible after etching to a depth of about 60 nm. Ti‐implanted surfaces, however, showed no grain relief until a depth of 240 nm, well beyond the implanted ion range (R p ∠60 nm). Individual grains on nonimplanted as well as Ne and Ar‐implanted surfacesetched with a rough texture. On the N‐implanted surfaces, however, grains remained smooth until etched to a depth well beyond the implanted region. The absence of grain relief on etching a Ti‐implanted surface is ascribed to isotropic sputtering from an amorphous surface. The absence of grain roughness on etching N‐implanted surfaces may be due to locally isotropic sputtering from a reacted, e.g. nitrided, surface layer, or from a more stable microstructure, e.g. nitrogen‐stabilized austenite.