Effects of Stress

A specific corrosive substance in particular the presence of Cl-, OH-, NO3, or NH4 ions. 

Mild stress can cause cracking the residual stresses from fabrication and welding are sufficient. 

For a general discussion of the mechanism of stress corrosion cracking see Fontana (1986). 

Some classic examples of stress corrosion cracking are  

The stress corrosion cracking of stainless steels in the presence of chloride ions. 

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In this study, the appearance and evolution sequence of planar slip bands, in addition to a dislocation cell structure with increasing e,, is identical to that observed in quasi-static studies of the effects of stress path changes on dislocation substructure development [27]. The substructure evolution in copper deformed quasi-statically is known to be influenced by changes in stress path [27]. Deforming a sample in tension at 90° orthogonal to the... 

Fig. 2-22 Effect of stress intensity range dJC on crack propagation for a notched specimen of X60 steel in 3.5% NaCl solution at 0.1 Hz.

Certainly the most prominent feature of the breakdown process is its dependence on the polarity of the electric field relative to the shock-velocity vector. This effect is manifest in current pulse anomalies from minus-x orientation samples or positively oriented samples subjected to short-pulse loading (see Fig. 4.8). The individual effects of stress and electric field may be delineated with short-pulse loadings in which fields can be varied by utilizing stress pulses of various durations [72G03]. 

Typical S-N (stress versus number of cycles) curves for various metals and composite materials are shown in Figure 6-4 [6-3]. The boron-epoxy composite material curve is much flatter than the aluminum curve as well as being flatter than the curves for any of the metals shown. The susceptibility of composite materials to effects of stress concentrations such as those caused by notches, holes, etc., is much less than for metals. Thus, the initial advantage of higher strength of boron-epoxy... 

Recognize the effects of stress in case of emergencies. The actual emergency probably will differ considerably from those practiced. The reluctance to acknowledge that the emergency exists is a well-known cause of delayed response. Complex decisions are doomed to failure... 

In normal drilling operations, as well as in such operations as DST or washover, drill pipe is subjected to combined effects of stresses. 

Lynes, W., Intergranular Corrosion of Alpha-brass and Some Effects of Stress , Corrosion, 21, 125 (1965)... 

The occurrence of stress-corrosion cracking in the martensitic steels is very sensitive to the magnitude of the applied stress. For instance, a 13% chromium martensitic steel tested in boiling 35% magnesium chloride solution (125.5°C) indicated times to failure that decreased abruptly from more than 25(X)h to less than 0.1 h as the applied stress was increased from 620 MPa to about 650 MPa (Fig. 8.25). However, the effects of stress on time to failure are not always so dramatic. For instance, in the same set of experiments times to failure for a 17Cr-2Ni martensitic steel gradually decreased from more than 800 h to about 8 h as the applied stress was increased from 500 MPa to 800 MPa. 

Fig. 3-7 Examples are shown of elasticity changes for engineering TPs involving one cycle of loading and unloading. The curves show effects of stress and time under load and strain recovery after loading.

Antidepressant Drugs. Figure 1 Effects of stress as a model for depression and the reversal by the use of antidepressants. Multiple intracellular targets might be involved in the regulation of plasticity and resilience by antidepressants, which block extracellular transporters. Adapted from [1],... 

There have been many studies of the effects of stress on gas exchange. Some have involved leaves that were fully expanded and some have been on leaves that were still expanding. Sometimes the stresses have been chronic, and sometimes they have been imposed for short periods. Sometimes the stresses have been severe, and sometimes they have been mild. Often they have been imposed more rapidly than occurs naturally. 

Winkel-Shirley, B., Biosynthesis of tlavonoids and effect of stress, Curr. Opin. Plant Biol, 5, 218, 2002. 

Environmental Cracking The problem of environmental cracking of metals and their alloys is very important. Of all the failure mechanism tests, the test for stress corrosion cracking (SCC) is the most illusive. Stress corrosion is the acceleration of the rate of corrosion damage by static stress. SCC, the limiting case, is the spontaneous cracking that may result from combined effects of stress and corrosion. It is important to differentiate clearly between stress corrosion cracking and stress accelerated corrosion. Stress corro-... 

Several neuropeptides are under current investigation for their role in anxiety disorders. Important neuropeptides include neuropeptide Y (NPY), substance P, and cholecystokinin. NPY appears to have a role in reducing the effect of stress hormones and inhibiting activity of the LC. Both mechanisms may contribute to the anxiolytic properties seen experimentally. Substance P may have anxiolytic and antidepressant properties. This may be due in part to its effects on corticotropin-releasing hormone.21... 

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