Short Crack Behavior on PWSCC of Mill Annealed Alloy 600

Abstract

A short crack behavior is essential to construct a life time prediction model of a light water reactor component. The objective of this study is to evaluate a short crack behavior on primary water stress corrosion cracking (PWSCC) of mill annealed alloy 600. Constant load tests were conducted to investigate a short crack growth rate. Test time was fixed at 1000, 3000, 3880 and 6940 hr and no specimen was fractured during the test. Crack length was measured for all cracks and plotted to the Weibull probabilistic sheet. By calculating the maximum crack length using the Weibull parameter at each test time, crack growth rates were obtained. We found there were 2 kinds of crack growth stages. This means short cracks transform from slow speed stage to fast speed stage. Furthermore distribution of inclination of grain boundaries, which were cracked was investigated to consider the factors which influence to crack propagation. Consequently it is revealed that the crack

Influence of grain boundaries on short crack growth behaviour of IGSCC

“…A study concerning short crack growth rates in alloy 600 on primary water stress corrosion cracking (PWSCC) was previously reported by the author 7–9 . Some results concerning short crack growth behaviour of that previous study are quoted in this present work.…”

“…Figure 2 shows a Weibull probability plot for the crack depth distribution obtained in the experiments 8 . The cumulative probability function F ( x ) of the Weibull distribution is represented as follows: where α , γ and m are the scale, location and shape parameter, respectively.…”

“…In order to examine the effect of the grain boundaries on the crack initiation and propagation, a distribution of inclinations of cracked grain boundaries was investigated. This inclination was categorized as ‘initiation grain boundary’ and ‘propagation grain boundary’ 8 . The former was defined as the first grain boundary from the surface and the latter was defined as the grain boundary which existed at a deeper position above the second grain boundary from the surface.…”

“…This inclination was categorized as 'initiation grain boundary' and 'propagation grain boundary'. 8 The former was defined as the first grain boundary from the surface and the latter was defined as the grain boundary which existed at a deeper position above the second grain boundary from the surface. Test results are shown in Fig.…”

Influence of Crystal Grain on Stress Intensity Factor of Microstructurally Small Cracks

“…It falls to less than 40 percent of that for a straight crack (α = 0). In the case of intergranular cracking of SCC, the angle of deflection can be more than 60°, and decreases in the SIF due to the deflection make the crack growth rate slow or arrested the growth of microstructurally-small-cracks (15) . On the other hand, the Mode II SIF increases even under pure tensile loading, although the maximum Mode II SIF is smaller than the Mode I SIF in the range of α < 90°.…”