Using a SERT (slow extention rate technique) method, stress corrosion cracking of Type 304 stainless steel rods with a 0.2R round notch was studied in 20% NaCl aqueous solution at 100°C in the crosshead speed (CS) between 3×10^-5mm/min and 1×10^-2mm/min. The effects of potential, alloying elements and applied stress (constant load test) on SCC were also investigated. Tested specimens were examined by a scanning electron microscope and an optical microscope. Cracks accompanied with corrosion pits were found at CS≤4×10^-4mm/min around the corrosion potential. Transgranular stress corrosion cracks were observed and the fracture surface was similar to that obtained in 42% MgCl₂ aqueous solution. Corrosion pits formed during SCC tests were characteristically classified repassivated small pits which were not so damaging mechanical strength, growing pits damaging mechanical strength and those inducing SCC. The pit With SCC was a covered one, which was crevice-like and seemed to make an appropriate condition of solution for SCC (low pH, concentrated Cl^-). Nucleation and growth of pits were also dependent upon CS, that is, the apparent pitting potential was most cathodic at CS of 1×10^-4mm/min. Alloying elements such as Mo and Cu moved the corrosion potential of unstressed specimen from -0.380V to -0.325V (SCE) and increased an incubation time in SCC.

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The influence of temperature and chloride content on the behavior of localized corrosion such as crevice corrosion and on the occurrence of stress corrosion cracking have been investigated by long term immersion of the spot-welded specimens of ferritic and austenitic stainless steels in 100-21, 000ppm Cl^- solutions at 40°-80°C. The extent of the corrosion activity of the steel during the test period was followed by galvanic couple current between the test specimen and the crevice-free specimen prepared from the same kind of the steel. In the low carbon Type 430 ferritic stainless steel intergranular corrosion as well as pitting corrosion took place in all test runs and these corrosion actions continued through-out the test period. Titanium stabilized ultra-low carbon ferritic stainless steels, 17Cr-Ti, 17Cr-1 Mo-Ti and 18Cr-2 Mo-Ti, exhibited, however, only pitting type failure and this type of corrosion became inactive in the early period of test. Stress corrosion cracking in austenitic stainless steels, Type 304 and Type 316, took place at 60°C, but did not occur at 40°C in all runs. The extent of stress corrosion failure in Type 304 was more significant than those in Type 316. The corrosion actions in the presence of stress corrosion cracking continued throughout the test period except for one run in Type 304, but became inactive in Type 316 in the early period of test even in the presence of cracking.

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A review has been made en the effects of alloying elements on toughness, intergranular and pitting corrosion of low interstitial ferritic stainless steels. Critical amount of (C+N) to maintain good toughness and corrosion resistance is discussed. The role of Ti and Nb in improving these properties was also discussed. This review is extended to show the effects of Cr, Mo and Ni on corrosion resistance, and metallurgical factors which induce stress corrosion cracking to ferritic stainless steels.

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