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Tham khảo tài liệu 'volume 20 - materials selection and design part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | content or corrosion potential b measuring the reaction rates for the crack-tip alloy environment system that corresponds to the engineering system and c defining the crack-tip strain rate in terms of continuum parameters such as stress stress intensity and loading frequency. Extensive work has been conducted in these areas which has been reviewed elsewhere Ref 10 . As a result of these examinations of the crack-tip metallurgical chemical and stressing conditions practical crack-propagation-rate algorithms of the following form have been developed for stainless steels in 288 C BWR water F 7.8 X 10 3 73-6 éct 77 EPR 0c ẽct 6 X lO 14 4 for constant load c Ct 5capp for monotonically increasing strain Cct IOOĨMr AK4 for cyclic loading Eq 25 Eq 26 Eq 27 Eq 28 Eq 29 where A .is the conductivity of coolant PS cm1 is the corrosion potential of the steel mVshe EPR is the measurement of grain-boundary chromium depletion due to heat treatment annealing or welding K is the stress intensity ksiy 111 Ềapp is the applied strain rate s 1 ỪÍS the cyclic-loading frequency s 1 is the stress-intensity amplitude under cyclic loading and ÂR is a parameter that is a function of the mean stress under cyclic loading. Validation of Life-Prediction Algorithms and Their Application. The overall comparison between the observed and theoretical crack-propagation rates in type 304 316 stainless steels in 288 C water is shown in Fig. 41. The laboratory database upon which this comparison was made was obtained under a wide range of stressing static monotonically increasing and cyclic load material solution annealed vs. various degrees of sensitization and water composition 10 ppb 02 to 8 ppm 02 0.1 to 10 cm1 . It is seen that there is a reasonable agreement between observation and prediction. Fig. 41 Comparisons between observed and theoretical crack-propagation rates for type 304 316 stainless steels in 288 C water. This database represents a wide combination of stressing material and .