Stress corrosion estimation

For detecting stress-corrosion cracks and estimating their depth of penetration, the ultrasonic technique and, to a lesser extent, A -radiography, have proved successful. 

Since 1973 [3] and 1975 in Dresden 2 [4], on line measurements of redox potential have been performed in the BWRs (Boiling Water Reactors) primary coolant in order to verify the IGSCC (Intergranular Stress Corrosion Craking) susceptibility of austenitic stainless steel components. Such measurements turned out to be fundamental for estimating the effect of hydrogen addition as a remedy for IGSCC [5-6]. 

Kim] Kim, H.P., Hwang, S.S., Lim, Y.S., Kuk, I.H., Kim, J.S., Effect of Heat Treatment and Chemical Composition on Caustic Stress Corrosion Craeking of Alloy 600 and Alloy 690 , Key Eng. Mater., 183-187, 707-712 (2000) (Electrochemistry, Interface Phenomena, 10) [2000Mie] Miettinen, J., Howe, A.A., Estimation of Liquidus Temperatures for Steels Using Thermo-... 

Stress-corrosion cracking threshold in seawater has been estimated at 77 to 90 MPaVnT (70 to 82 ksi Vin.) (Aerospace Structural Metals... 

There is a reasonable agreement among these three estimates of the H diffusion coefficient in Mg in Fig. 8.25, so that it is possible to put a line through all these data, and extrapolate to 23 °C. This yields an estimate of the diffusion coefficient at ambient temperature to be 10 m /s-10 cm /s. This value of the H diffusion coefficient is sufficient to allow significant H transport ahead of a stress corrosion crack in Mg at ambient temperature. A least squares regression through the data [184—186] of Fig. 8.25 yielded the following equation for the diffusion coefficient of H in Mg,... 

Conclusions. It was concluded that the cracking of the flange occurred by a combination of stress corrosion and fatigue. The cracking was accelerated because of an inadvertent fit-up stress during installation. The age of the crack could not be established. However, a reevaluation of prior x-ray inspections in this area would result in some close estimate of the age of the crack. End grain exposure frirther promoted SGC. 

A further estimation of the corrosion resistance of maraging steel can be obtained from data on the rate of crack propagation. Although the rate of crack propagation has been found to be a function of stress intensity in some alloys, for many alloys and heat treatments there is a range of stress... 

A storage tank for concentrated nitric acid will be constructed from aluminium to resist corrosion. The tank is to have an inside diameter of 6 m and a height of 17 m. The maximum liquid level in the tank will be at 16 m. Estimate the plate thickness required at the base of the tank. Take the allowable design stress for aluminium as 90 N/mm2. 

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