Pits in Stainless Steel

More recently, Fontana and Greene measured the current between a pit in stainless steel and the surrounding metal the pit was allowed to form, and cut out from the surrounding metal (the cathode), its edge was insulated and it was then replaced in the hole with a suitable connection for measuring the current flow between the pit and the surrounding metal. These workers showed that under certain conditions was about a thousand times... 

Table 1.18 pH, chloride ion concentration and potential for artificial pits in stainless steels ... 

Szklarska-Smialowska, Z., Electron Microprobe Study of the Effect of Sulphide Inclusions on the Nucleation of Corrosion Pits in Stainless Steels , Br. Corros. J., S, 159 (1970) Weinstein, M. and Speirs, K., Mechanisms of Chloride-activated Pitting Corrosion of Martensitic Stainless Steels , J. Electrochem. Soc., 117, 256 (1970)... 

Development of Pits in Stainless Steel inO-5 n NaCl + 0 -1 n H2SO4 Solution , Corns. Sci., 12, 925 (1972)... 

A number of industrial applications have been described including successful subsea installation . Double layer activation has been used in the laboratory for estimation of both shape and growth of pits in stainless steel. Advantages of TLA are that (a) the concept is easily understood, (b) interpretation is relatively easy and (c) the system installation can be non-invasive. 

Pits in Stainless Steel. Much work has been carried out on pits in stainless steel because of their particular technological importance. As with the A1 case described in some detail in Section 12.3, the work on stainless steel in contact with Cl" containing media points to an entry point for CF diffusion through the passive film. These entry points (the beginning of pits) may arise from inclusions in the steel and for 304 stainless steel in particular, it is MnS inclusions that are critical (Szklarzcka-Schmialowska, 1986). 

K. OsozawaandN. Okato, Effect of Alloying Elements, Especially Nitrogen, on Initiation of Pitting in Stainless Steel, Passivity and Its Breakdown in Iron and Iron-Base Alloys, R.W. Staehle and H. Okada, Ed., National Association of Corrosion Engineers, 1976, p 135-139... 

Figure 11.5 [46] illustrates a train of current pulses resulting from the nucleation, growth and death of metastable pits in stainless steel, polarized in a dilute NaCl solution. The... 

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