Browsing by Author "Durowoju, M. O."
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Item FACTORIAL DESIGN BASED OPTIMISATION OF CREVICE CORROSION FOR TYPE 304 STAINLESS STEEL IN CHLORIDE SOLUTIONS(ADVANCES IN MATERIALS SCIENCE (De Gruyter), 2016-06-01) OGUNLEYE, O. O.; Adeniyi, A. G.; Durowoju, M. O.The effects of chloride concentration, creviced scaling factor and immersion time on the percentage area and maximum depth of attack for Type 304 stainless steel (SS304) in chloride solutions were investigated. The crevice assembly comprised of coupon (SS-304), polytetrafluoroethylene (crevice former) and fasteners (titanium bolt, nut and washers). The full immersion tests were based on ASTM G-78 using full factorial design to study the effects of chloride concentration (1.5, 3.0 and 4.5 w/w%), crevice scaling factor (8, 16 and 24) and immersion time ( 15, 30 and 45 days) on the percentage area of attack (Y1) and maximum depth of attack (Y2) of SS-304. Data obtained was used to develop and optimize the models of Y1 and Y2 in terms of the three factors using Response Surface Methodology (RSM). The R2 of Y1 and Y2 were 0.98 and 0.91, respectively. The minimum Y1 (5.63%) and Y2 (3.32x10-7 mm) were obtained at 4.5% chloride concentration, 20 scaling factor and 15 days immersion time. The predicted optimal conditions agreed with the experimental results for validation with a maximum absolute relative error of 5.75%.Item Modelling stochastic response of type 304 stainless steel (SS-304) crevice corrosion in chloride environments(Indian Chemical Engineer (Taylor & Francis), 2018-11-26) Adeniyi, A. G.; Ogunleye, O. O.; Durowoju, M. O.; Odeyemi, S. O.The stochastic corrosion response of creviced SS-304 in chloride environment was studied. The crevice assembly used for this study comprised coupon (SS-304), polytetrafluoroethylene (crevice former) and fasteners (titanium bolt, nut and washers) designed in three configurations with crevice scaling factor of 8, 16 and 24, respectively. An immersion test was carried out on each configuration having 40 crevice sites and immersed in various chloride solution concentrations of 1.5, 3.0 and 4.5 w/w % simulating environmental conditions A, B and C, respectively, for 60 days to study the stochastic nature of the initiation and propagation of cc in chloride environments according to ASTM G-78. Data obtained were used to develop a Monte Carlo’s model of the crevice corrosion pattern which confirmed the stochastic nature of the crevice corrosion. The probability of attack of SS-304 within 30 days was 0.150, 0.300 and 0.425 for A, B and C, respectively, while the extreme value of the propagated depth of attack was predicted from the stochastic models developed. The developed model is a useful tool for predicting the maximum depth of attack possible under uncertain crevice corrosion of SS-304 in chloride environment.