Cladding and alloying of AISI 316 stainless steel on plain carbon steel were performed by means of electron beam processing. The electrochemical corrosion behaviour was investigated at different depths from the original surface, in dilute sulphuric acid. The microstructural transformations were studied by scanning electron microscopy and X-ray microanalysis. In the cladding, a duplex structure was obtained with a fine network of delta ferrite precipitated both at grain and at subgrain boundaries; the electrochemical curves were practically identical with those of the parent material. After the alloying, the dillution of the chromium and nickel induced a martensitic transformation with a remarkable increase in the hardness of the resulting layer. The corrosion behaviour was similar to that of an alloy with a lower chromium content.