Slip lines persistent

Fig. 1.43 Persistent slip line in aluminum alloy that reveals the nature of damage in the form of pore beads [55]...

Thompson, Wadsworth e Louat [52] testing mirror-polished specimens of polycrystalline high purity copper, found that if they would interrupt tests, from time to time, and electro polish a surface layer 2 pm depth, most of slip lines and bands would disappear with the exception of some that, instead, would persist. This was the sign of a surface damage that, though microscopic, was deeper than 2 pm. 

Fig. 1.49 Appearance of micro cracks along persistent grain boundary in aluminum a grains have heavily undergone plastic slips, b upon electropolishing the specimen slip lines almost disappear, but grain border remain visible because affected by micro cracks, c and d after repeating cycling and electropolishing...

Fig. 1.55 Appearance of persistent slip bands broken line) in a specimen of mild steel 0.09 % C tested in reci nocating bending. Wohler curve is also shown full line) [78]...

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