MATHEMATICAL MODELING OF STRESS CORROSION CRACKING

THE WORK DESCRIBED IN THIS PROPOSAL IS DIRECTED TOWARD QUANTITATIVELY UNDERSTANDING THE ELECTROCHEMISTRY OF LOCALIZED CORROSION IN AQUEOUS ENERGY PRODUCTION AND CONVERSION FACILITIES TO PROVIDE A BASIS FOR SOLVING THESE EXPENSIVE PROBLEMS. THE PRINCIPAL INVESTIGATOR AND COLLABORATORS PUBLISHED IN 1969 THE FIRST QUANTITATIVE MATHEMATICAL MODEL FOR STRESS CORROSION CRACKING OF TITANIUM. THIS MODEL ACCOUNTED FOR MANY ASPECTS OF SCC BUT DID NOT DESCRIBE EVENTS IN THE MOST IMPORTANT REGION, THE CRACK TIP. SUBSEQUENT RESEARCH BY THE P.I. ON PITTING CORROSION SHOWED THE IMPORTANT ROLE OF SALT FILMS ON THE CORRODING SURFACE. IT IS PROPOSED TO MATHEMATICALLY MODEL IN PHASE I THE ELECTROCHEMICAL TRANSPORT AND KINETIC PROCESSES THAT OCCUR IN TUNNEL CORROSION OF ALUMINUM WHICH HAS MANY OF THE FEATURES OF STRESS CORROSION CRACKING AND IS BELIEVED TO HAVE A SALT FILM AT THE TUNNEL END. THIS SYSTEM IS SIMPLER AND EASIER TO MODEL THAN SCC BECAUSE THE GEOMETRY IS BETTER DEFINED AND IT IS UNCOMPLICATED BY METALLURGICAL AND FRACTURE MECHANICS FACTORS.