| Available from UMI in association with The British Library.; In the present work, stress corrosion cracking in two different systems related to energy-producing industries (i.e. high pressure gas pipeline steel in carbonate/bicarbonate solution and alloy IN 600 in the primary side water of nuclear power plant) were studied.; Intergranular environment-induced cracking of the pipeline steel in IN Na{dollar}sb2{dollar}CO{dollar}sb3{dollar} + IN NaHCO{dollar}sb3{dollar} solution was studied under environmental conditions promoting maximum susceptibility, i.e. 75{dollar}spcirc{dollar}C and {dollar}-{dollar}650mV (sce). The effects of the cyclic loading variables: frequency, stress amplitude, maximum stress and test time, on the threshold stress for stress corrosion cracking, and the rate of crack growth and nucleation were studied. Values of the threshold stress for the cyclic loading tests were lower than the values obtained under static loading conditions. Detailed studies of the crack coalescence behaviour of surface cracks have indicated the importance of the lateral distance between the tips of adjacent cracks for crack coalescence. Conditions for crack coalescence in terms of the interaction zone ahead of the crack tip were studied. The results have shown that the interaction zone of a given crack increases with increase in the crack length, whereas the effect of the applied stress within the tested range was not significant for cracks of comparable crack lengths. A crack growth simulation model based on the experimental observations was developed using the Monte-Carlo approach to a random selection of crack sites. This model also takes the phenomenon of crack coalescence into account. The results from the simulation program are reasonably close to the experimental results, (in terms of the crack growth pattern and the number of cycles to reach a critical crack length).; In relation to the stress corrosion cracking of alloy IN 600 in primary side water, the effects of various heat treatments of IN 600 were studied with the aim of exploring the role of chromium depletion at the grain boundaries on the susceptibility of the alloy to intergranular stress corrosion cracking. These results have shown that the heat treatments that lead to chromium depletion at the grain boundaries also make the alloy susceptible to intergranular stress corrosion cracking in the primary side water and steam/hydrogen environments. (Abstract shortened by UMI.)... |
