Creep from Scribe

Average Creep from Scribe after 1 Year Weakly Accelerated Field Exposure... 

Changes that can be seen by the unaided eye or with optical (light) microscopes, such as rust-through and creep from scribe... 

Direct evidence of corrosion can be obtained by macroscopic measurement of creep from scribe, rnst intensity, blistering, cracking, and flaking. 

Xj(,(,ei is the response (creep from scribe) from the accelerated test Xfleid is the response from field exposure taccei is the duration of the acceleration test tfleid is the duration of the field exposure... 

For example, after running test XYZ in the lab for 5 weeks, 4 mm creep from scribe was seen on a certain sample. After 2 years outdoor exposure, an identical sample showed 15 mm creep from scribe. The rate of acceleration, A, could be calculated as ... 

Corrosion creeping from the scribe to the interface of the E-coat and the substrate surface for the surfaces with poor adhesion. The corrosion depth is similar to that of away from the scribe... 

Figure 32.3 shows the scanned images of SO2 salt spray-tested IVD Al-coated 7075-T6 panels one control, and two E-coated panels. The direct application of E-coat to IVD-coated panels (with no plasma treatment) did not provide corrosion protection as good as that of the chromate conversion oated control panel more corrosion creep from the scribed lines was observed on [7I]/E panels than on the [7pI]CC/E... 

After completing corrosion testing exposure, the panels were rinsed with distilled water and visual observations were made. The panels were then subjected to Turco 5469 paint stripper solution to strip off the E-coat or spray primers (including the controls) from the scribed surface, so that the effect of corrosion beneath the coatings and away from the scribes could be viewed. These panels were then used to estimate the average corrosion creep widths, in order to compare the corrosion performance of the different sample systems [5]. 

Corrosion creeps away from the scribe as well as eorrosion takes place away from the scribe due to permeation of test solution. 

Finally, there is a property of high-performance carbon fibers, both PAN and mesophase pitch-based, which sets them apart from other materials. They are not subject to creep or fatigue failure. These are important characteristics for critical applications. In a comparison of materials for tension members of tension leg platforms for deep-.sea oil production de.scribed by Salama (1997), carbon fiber strand survived 2,000,000 stress cycles between 296 and 861 MPa. In comparison, steel pipe stressed between 21 and 220 MPa failed after 300,000 cycles. Creep studies on PAN and... 

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