: Two important advances over the past 40 years enable the optimization and management of the structural integrity of components in high performance applications. First, the solid mechanics conununity established linear elastic fracture mechanics as the premier framework for modeling the damage tolerance of fracture critical components (Irwin and Wells, 1997; Paris, 1998). Second, materials scientists developed metals with outstanding balances of high tensile strength and high fracture toughness (Garrison, 1990; Wells, 1993; Boyer, 1993; Starke and Staley, 1995; Olson, 1997; Kolts, 1996). An example of achievable strength-toughness properties is provided in Fig. 1, a plot of plane strain fracture toughness vs. tensile yield strength (sigma-YS) for ultra-high strength steels (UHSS) and beta-Ti alloys precipitation hardened with a phase (Gangloff 2001). New nano-scale characterization and high performance computational methods provide for additional advances in the mechanical performance properties of structural metals. These modem alloys and analysis tools satisfy technological needs for optimization and management of component performance in demanding fatigue and fracture critical applications in the aerospace, marine, energy, transportation, and defense sectors.

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Hydrogen Assisted Cracking of High Strength Alloys

Modelling of environment assisted cracking

6.02 – Hydrogen-assisted Cracking

Alloy 600 is a material commonly used to construct the tubing in the steam generators (SG) of pressurized light water reactors (PWR) and of CANDU heavy water reactors. It is well established which variables and to which extent they influence the crack growth rate (CGR) in Alloy 600 exposed to high temperature (deaerated) water (HTW), especially in very aggressive conditions. There is evidence that the same variables that influence CGR also control the crack induction time. However, there are only a few data on crack induction time and no detailed explanation of the events that lead to the nucleation of a crack on an apparent smooth tube surface. In this paper, a critical review of the mechanisms of stress corrosion cracking (SCC) is given and, an interpretation of the events occurring during the long ({approx} 15 y) induction times observed in plant is postulated.

About the mechanism of stress corrosion cracking of Alloy 600 in high temperature water

The mechanism of stress corrosion cracking of alloy 600 in high temperature water

The crack growth rate for IGSCC has been measured in two nickel base alloys, Alloy 600 and X-750, in deaerated, superheated steam between 300 and 400° C. Measurements were made using MWOL ...

P. G. Shewmon

Papers

IGSCC crack growth of alloy 600 and X-750 in steam