The effect of Cl^- content, together with temperature and dissolved oxygen on corrosion resistance of aluminum can stocks in citric acid solution was examined to evaluate the suitability of packing higher Cl^- beverages in aluminum cans. Though corrosion rate in immersion test increased slightly with increasing Cl^- content, the effects of temperature and dissolved oxygen were much greater than that of Cl^-. Pitting corrosion was observed only in the solutions containing sufficient dissolved oxygen, independent of Cl^- content. Aluminum dissolution depended greatly on temperature and oxygen content. The same result was observed in test pack. The effects of these factors on corrosion rate and pitting corrosion could be understood in terms of electrochemical polarization characteristics of the aluminum can stocks in the solution. It is concluded that shelf life of aluminum cans for practical purposes is not affected by Cl^- content in beverages when packed with innert gas.

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Intergranular corrosion of austenitic stainless steels is associated with the chromium-depleted zone surrounding chromium carbide precipitated at grain boundaries. Computer simulation of intergranular corrosion by means of finite element method (FEM) was compared with the results of electrochemical potentiokinetic reactivation test and Strauss test. Computed corrosion rate of SUS 304 steel agreed with experimental results when specimens were isothermally heated at the temperature range of 823-1, 023K. Agreement between computed and experimental results was also observed for 304 steel continuously cooled from 1, 073K or below. For samples cooled from 1, 073K or above, computed corrosion rate was higher than experimental data because of precipitates deposited inside grains. From these results, the simulation by FEM was found to be able to predict the sensitization of 304 steel at the temperature range of 823-1, 073K.

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The influence of Ge addition on the corrosion resistance of 25Cr-6Ni ferrite-austenite duplex steel has been studied. Results obtained were summarized as follows.
(1) Alloying of Ge up to 2.0wt.% had no influence on the corrosion rate in 65wt.% HNO₃ solution. In reheated condition, the susceptibility for intergranular corrosion of 25Cr-6Ni steel and Ge bearing steels was increased with ferrite amounts.
(2) Corrosion rate of 25Cr-6Ni steel was decreased with small amounts of Ge addition in 5wt.% H₂SO₄ solution at boiling temperature. But some of specimens in reheated treated at 1, 300°C were revealed intergranular corrosion and some grains dropped. The critical current density, I_Cr was reduced by Ge addition in 5wt.% H₂SO₄ solution at boiling temperature.
(3) Alloying of Ge made the corrosion rate of 25Cr-6Ni steel more decreased in 50g/l· FeCl₃+1/20N·HCl solution at 70°C. The pitting potential, V′_C·10 of Ge bearing steels were more noble than V′_C·10 value of 25Cr-6Ni steel in 0.5mol/l NaCl solution at 30°C.
(4) It was found that the pitting potential, V′_C·10 of 25Cr-6Ni and Ge bearing steels was fairly correlated with the repassivation potential for crevice corrosion, E_R in 0.5mol/l NaCl solution at 30°C.

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Base on failure analyses of external IGSCC of Type 304 in an atomosphere containing sea salt particles and SCC test results by a wet and dry salt spray method, the following facts have been obtained:
(1) External IGSCC of Type 304 vessels used without any surface insulations occurs due to a combination of the following conditions, (i) sensitization at grain boundaries, (ii) residual stress, (iii) an atmosphere containing sea salt particles, and (iv) rusting on the surfaces of the vessel.
(2) The sensitization of Type 304, essentially the susceptibility to IGSCC is remarkably increased by cold work.
(3) When the reactivation ratio of Type 304 is above approx. 5% in EPR tests, Type 304 is susceptible to external IGSCC.

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The effect of aluminium foil wrapping on the prevention of the stress corrosion cracking of austenitic stainless steels caused by wind-borne sea salt particles (ESCC) was evaluated by a 100-days salt spray test. The results were compared with those of other conventional surface treatments for austenitic stainless steels, e. g., shot peening, sand blasting and paint coating. It was exhibited that both aluminium foil wrapping and shot peening were the most economical and effective methods for preventing ESCC. The paint coating was also confirmed to be effective for preventing ESCC.

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The measurements of localized corrosion for metals using in chemical plants by non-destructive methods such as ultrasonic, X-ray, eddy current etc. are explained. Several examples of estimation for corrosion damage in chemical plants are discussed.

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