AbstractsChemistry

"The objective of this investigation was to determine if stress corrosion failure of 300M steel is accelerated by the application of cathodic protection. Testing was conducted on notch tensile specimens that were coated with vacuum cadmium, electroplated cadmium, and vacuum aluminum. All specimens were stressed and placed in an aqueous sodium chloride environment. The failure times for the specimens were monitored and graphs were drawn which characterized the stress corrosion resistance of 300M steel and the cathodic protection systems. Fractography techniques were used to study the failure surfaces to determine the type of failure mechanism. The results of this thesis program indicated that, for 300M low alloy steel: 1) The hydrogen evolved during cathodic protection of 300M steel by vacuum aluminum and vacuum cadmium embrittles the steel and accelerates failure. 2) Cathodic protection afforded by vacuum cadmium accelerates stress corrosion failure of 300M steel at all stress levels and significantly below 60% NTS. 3) Vacuum aluminum does not afford adequate protection to 300M steel and premature failure can be expected at all stress levels. 4) Electroplated cadmium affords excellent cathodic protection to 300M steel and does not accelerate failure. 5) A notch through the cathodic coating to the base steel does not increase the failure susceptibility of 300M steel" – Abstract, pages ii-iii.