Intergranular Stress Corrosion Cracking (IGSCC) and Intergranular Corrosion (IGC) behaviors of nickel-base weld metals of Types 82 and 182 were examined by means of various accelarated tests in oxygenated high temperture pure water and the ASTM G28 test, respectively. Ordinary nickel-base weld metals showed large heat-to-heat variations in IGC and IGSCC susceptibility. The behavior could be characterized in terms of stabilization parameter (N), which was defined as the number of atoms of stabilization elements per a carbon atom of material itself. The SCC resistant, new weld metals could be successfully produced by the stabilization parameter (N) control, here, mainly by niobium addition and carbon adjustment. The nickel-base weld metals of high N values (≥12) were highly resistant to IGC and IGSCC. The theoretical mechanism of stabilization parameter (N) control was discussed.

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A polarization study on polished, rusted and phosphated steels with various painted surfaces has been made in 3% NaCl aqueous solution at 25°C. With oil painted steels, i_corr increased sharply after a certain time (critical time) and electrical resistance decreased at the same time. The shorter the critical time and the time for electrical resistance to reach 10⁵ohm/40cm², the larger the rusted and blistered surface area in the salt spray test becomes. With zinc rich-epoxy painted steels, however, i_corr increased and electrical resistance decreased gradually with time also. In conclusion, the corrosion resistance of oil painted steels can be estimated from i_corr and electrical resistance values which show a good correlation with the results of the salt spray test and the immersion test. In general, the corrosion resistance of rusted-painted steels cannot be estimated well from the tan δ value at an initial stage of immersion.

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It is generally known, that aluminum and aluminum alloys do not corrode easily in a normal environment.
However under certain circumstances where either the humidity or industrial pollution is high, corrosion will occur on the surface of aluminum. Thus, this study examines the corrosive effect on aluminum contacted with natural water (drinking water, spa water, sea water, sweat and water passing through a concrete slab). The characteristics of aluminum corrosion products by contact with natural water were examined by X-ray diffraction and scanning electron micrograph methods and electrochemical polarization curves were obtained by using on electrochemical polarization apparatus. The following facts have been found through this experimental study: (1) The Al corrosion product in drinking water is amorphous: (2) The Al corrosion product by sulfrated spa water is crystalline and is a compound of KAl(SO₄)₂·2H₂O, while that in chlorided spa water is amorphous: (3) The Al corrosion product in sea water is crystalline of Al(OH)₃ and that in sweat is amorphous: (4) The Al corrosion products in water passing through a concrete slab are Al(OH)₃ (Bayerite) and others. Anodic polarization curves have been obtained to examine the influence of Cl^- and SO₄^2- on initial corrosions of Al alloys 1050 and 6063 in spa water and sea water, and on corrosion of alloy 6063 of three different concentrations of water passing through a concrete slab.

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Recently, higher grade materials have been used for seawater pumps. However, it is desirable that more economical materials, e. g., cast iron, carbon steel, and type 316 stainless steel, are properly used for their services. This paper proposes the practical protection methods from seawater corrosion, i. e., (a) differential aeration cell corrosion (caused by the flow rate difference), (b) galvanic corrosion (caused by the use of two different materials), (c) crevice corrosion and others, which frequently occur in seawater pumps, and describes the applicability of these measures based on the actual application of seawater pumps.

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The characteristics of stress corrosion cracking (SCC) of Al-4%Cu alloy were investigated in 0.1mol/kg-H₂SO₄+1mol/kg-NaNO₃+0.05mol/kg-NaCl solution with reference to faceting dissolution and crystallographic planes of the fracture surfaces. Fracture time decreased exponentially with increasing potential above the stationary pitting potential, V_c=1.66 (vs. SCE), determined under no stressing. The kinds of facet were {100} and/or {110}, regardless of electrode potentials tested. There were many {100} steps and {110} facet pits formed by {100} and {110} faceting dissolution on the fracture surface. Cracks issued directly from the specimen surface at potentials near V_c, and issued from bottoms of pits at the increased potentials. Ductile fracture occured by reduction of area due to fast pitting at noble potentials than 1.80V. These results imply an important relationship between SCC and {hkl} faceting dissolution.

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