The study for direct SCC fabrication in STS 304 pipe

Abstract

Stress corrosion cracking is one of the aging phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and grown especially in dissimilar weldment of primary loop components. Among the three factors (susceptible material, residual stress, and corrosive environment) which make the SCC, the residual stress becomes a critical factor for stress corrosion crack when it is difficult to improve the material of the components and their environment under operating conditions. In this study, stress corrosion cracks were artificially produced on STS (stainless steel) 304 pipe itself by control of welding residual stress. The instrumented indentation technique and 3D finite element method (FEM) analysis (using ANSYS 12) were used to evaluate the residual stress values in the GTAW area. As the result of both FEM analysis and experiment, the stress corrosion crack was quickly generated and could be reproduced, and controlled by welding residual stress. Also non-destructive evaluation signals by Acoustic Emission will be discussed for the initiation and growth of SCC.

Interaction of Mechanical Heterogeneity and Residual Stress on Mechanical Field at Crack Tips in DMWJs

“…More detailed characterization of the DWMJ mechanical properties will greatly help the research of the crack tip mechanical field. In addition to the mechanical heterogeneity, the residual stress of the DMWJ also has a significant influence on the mechanical field of the crack tip, and it is the dominant driving force affecting SCC behaviors [18][19][20][21]. Some scholars found that the residual stress will noticeably change the stress and plastic strain of the crack tip, and the residual stress is redistributed on account of the crack propagation, which results in the mechanical field of the crack tip becoming more complex [22][23][24].…”

Scaling behavior of nonequilibrium measures in internally driven elastic assemblies

“…Examples include the stochastic fluctuations of biological assemblies such as chromosomes [10], the cytoskeleton [2,[11][12][13][14], and cellular membranes [15][16][17]. Indeed, while these fluctuations can at first sight appear indistinguishable from thermal Brownian motion, they are in many cases driven by energy-consuming processes at molecular scales [1,2,8,9,18,19]. This molecular scale activity can propagate to mesoscopic scales, giving rise to non-equilibrium dynamics that breaks detailed balance [9,[20][21][22][23][24][25] or that violates the fluctuation dissipation theorem [12,15,16,[26][27][28].…”