Stress corrosion cracking crack velocity

Fig. 8.11 Effect of beam deflection rate of cantilever beam specimens upon stress-corrosion crack velocity of carbon steel in carbonate-bicarbonate solution...

Fig. 8.48 Stress-corrosion crack velocity as a function of applied stress intensity factor...

In mechanistic studies of stress corrosion and also in the collection of data for remaining-life predictions for plant there is need for stress-corrosion crack velocity measurements to be made. In the simplest way these can be made by microscopic measurement at the conclusion of tests, the assumption being made that the velocity is constant throughout the period of exposure, or, if the crack is visible during the test, in situ measurements may be made by visual observation, the difficulty then being that it is assumed that the crack visible at a surface is representative of the behaviour below the surface. Indirect measurements must frequently be resorted to, and these... 

Figure 3. General relationship between stress-corrosion-crack velocity (v) and stress intensity factor (K)...

Figure 5. Effect of averaging on stress-corrosion-crack velocity in an aluminum...

Figure 7. Effect of solution concentration upon stress-corrosion-crack velocity in...

M. Kermani, J.C. ScuUy, The efiect of strain-rate upon stress corrosion crack velocity in a-brass in ammoniacal solutions, Corros. Sci. 19 (1978) 89—95, 97—110. 

Figure 8.10. Effect of stress intensity at a crack tip on stress-corrosion crack velocity.

The stress-corrosion crack velocity depends on the heat treatment used. Ti-8Mn has slower crack... 

The chapter builds on our critical reviews on Mg corrosion [1-4] and Mg SCC [5,6]. SCC [5-8] involves (1) a stress, (2) a susceptible alloy and (3) an environment. SCC is related to hydrogen embrittlement (HE). HE is SCC that is caused by hydrogen (H), which can be gaseous, can come from corrosion, or can be internal from prior processing. HE is often postulated as the SCC mechanism. SCC can be extremely dangerous. Under safe loading conditions, SCC causes slow crack growth. Fast fracture occurs when the crack reaches a critical size. SCC, for any alloy + environment combination, can be characterised by [7,8] the threshold stress, ctscc> threshold stress intensity factor, iscc> the stress corrosion crack velocity. 

PIq 12 EHbcI of vnler content (humidil on Ihe stress- corrosion crack velocity of a high-strength... 

Fig. 13 influence of various anions on stress corrosion crack velocity of a high-strenglh aluminum alloy (7079-7651) immersed in aqueous solutions. 2.5 cm thick plate, T-l crack orientation (long transverse grain direction nor mal to the liodure plane longitudinal direction of crack propagation In the fracture plane). 23 °C. Qsen circuit. Source Ref 13... 

Fig. 15 Effect of temperature and stress intensity on " the stress-corrosion crack velocity in high-strength aluminum alloy 039-761) exposed to disttted water. 2.5 cm thick plate. SI crock orientation (short transverse grain direction normal to the fracture plane longitudinal direction of crack propagation in the fracture plan. Source Ref 8...

In heat exchanger service, stainless steels can be used at much higher velocities than most common metals. There is, nevertheless, the ever-present possibility that stress-corrosion cracking may take place. This becomes much more likely as the metal temperature is raised. Any points at which high stress and high chloride concentrations occur are particularly prone to this type of failure. 

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