Stress Corrosion Cracking Data Research Articles

Interacting sensitivities of alloy 600 PWSCC to stress intensity factor, yield stress, temperature, carbon concentration, and crack growth orientation Alloy 600

Analyses of Alloy 600 primary water stress corrosion cracking data show there are interacting sensitivities of crack growth rate to applied stress intensity factor, yield stress, temperature, carbon concentration and crack growth orientation. The effects of these variables are expressed quantitatively using a crack advance model that is rate-limited by crack-tip-strain rate. Crystallographic texture and dynamic strain aging are considered to account for contrasting behavior observed for ST and LT orientation crack growth. Crack growth is conjectured to be rate-limited by “junction” pinning of mobile dislocations strengthened by interstitial carbon (ST) and “lineal” pinning by substitutional Cr and Fe (LT).

Overview Steam turbines Part 2 - Stress corrosion cracking of turbine disc steels

Stress corrosion cracking data for steam turbine disc steels are reviewed critically. The effect of material properties (steel cleanliness, yield strength), environment (oxygen, carbon dioxide, chloride level), temperature, and stress conditions, on the initiation and growth of stress corrosion cracks is assessed. For long cracks, growth rates are perceived to be independent of oxygen and CO2 concentration, and steel cleanliness, but the data are not wholly consistent. Unquestionably, the variables having the most dramatic effect are strength level and temperature. For medium strength disc steels, dissolved gases and steel cleanliness influence the 'initiation' of stress corrosion cracks, certainly in relation to pit development and growth, but the impact on short crack growth is less well established.

In situ analysis of delayed fibre failure within water-aged GFRP under static fatigue conditions

A stress corrosion model has been applied to the microscopic analysis of the delayed fibre failure processes occurring within a water-aged unidirectional glass/epoxy composite under static fatigue loading (i.e. relaxation). By means of in situ microscopic observations, the individual fibre failures within an elementary volume located on the tensile side of the flexural specimens have been quantified as a function of time under various applied strain levels. It was found that the time dependence of the in situ fibre failure processes obeyed a stress corrosion model. From the microscopic observations, it was possible to assess consistent values of the parameters characterising the in situ fibre strength distribution and the subcritical crack propagation law. A comparison with separate static fatigue experiments using unimpregnated fibre bundles demonstrated that the specific physico-chemical environment encountered by the glass fibres within the aged epoxy matrix can induce significant changes in the subcritical crack propagation rates, as compared to stress corrosion cracking data collected in humid air.

Status of JAERI Material Performance Database (JMPD) and Analysis of Irradiation Assisted Stress Corrosion Cracking (IASCC) Data

A material performance database for nuclear applications, which was named the JAERI Material Performance Database (JMPD), has been developed since 1986 with a view to utilizing various kinds of characteristic data of nuclear materials efficiently. The data stored in the JMPD are mainly fatigue crack growth data on low alloy steels, creep data on superalloys, tensile data on aluminum alloys and stress corrosion cracking data (Slow Strain Rate Testing (SSRT), crack growth rate, etc.) on austenitic stainless steels. Irradiation Assisted Stress Corrosion Cracking (IASCC) of austenitic stainless steels in high temperature water has been considered as a degradation phenomenon potential not only in light water reactors (LWRs) but in the rather common systems where the materials are exposed to radiation in the presence of water. This paper describes the present status of the JMPD, which is partially available through the Internet. Furthermore, some trials for the utilization of the system focused on the issues relating to IASCC are mentioned. The effect of alloy composition, dissolved oxygen and neutron fluence on IASCC susceptibilities and SCC growth rate could be drawn.

On the theory of stress-assisted diffusion, II

Similarity and general steady-state solutions of a recently developed strees-assisted diffusion theory are derived. General transient solutions are obtained analytically for certain classes of stress distributions. For general stress distributions a perturbation method is employed to produce transient solutions. Under appropriate conditions the derived solutions are reduced to previous formulae that have unsystematically appeared in the literature. Examples of interesting crack problems involving stress singularities as well as the elimination of singularities are considered. An equilibrium solution is utilized together with a straightforward physical argument to produce rationally two empirical formulae previously proposed in the literature to model embrittlement and stress corrosion cracking phenomena. This solution is further used to model embrittlement and stress corrosion cracking data more successfully than previous attempts. An appendix on certain preliminary elastodiffusive fracture criteria is given.

An Electrochemical Mass Transport‐Kinetic Model for Stress Corrosion Cracking of Titanium

The purpose of this work has been to develop a quantitative model for the electrochemical kinetic and mass transport processes in a propagating stress corrosion crack and to use the model to gain insight into manner in which these processes influence propagation. Analysis of the problem led to a system of simultaneous differential equations which with their appropriate boundary conditions were solved by computer implemented numerical methods. Comparison of computed behavior with experimental stress corrosion cracking data for a titanium alloy has guided the development of the model and the specification of critical stress corrosion cracking experiments. Such comparisons indicate that there is a halide ion current to the crack tip with some hydrogen ion discharge in the region downstream from the tip. A significant fraction of the current entering a crack appears to be involved in formation of soluble titanium ions in parallel with oxide formation on the walls.