Page 363 - Challenges in Corrosion Costs Causes Consequences and Control(2015)
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CORROSION DAMAGE, DEFECTS, AND FAILURES 341
20 μm
Figure 5.16 Ductile fracture surface of center of bolt. (Reproduced by permission of the
Society of Petroleum Engineers (20).)
10 μm
Figure 5.17 Intergranular region of fracture surface of bolt. (Reproduced by permission of
the Society of Petroleum Engineers (20).)
The final area of the fracture showed the presence of a shiny granular appearance,
indicating a sudden brittle (cleavage) fracture, which was also confirmed by the SEM
photographs showing cleavage steps and river pattern.
Fractured tie rods were sectioned and examined with an optical microscope, and
no evidence was found for microcracks at the root of the threaded notch and along
the fracture path.
Conclusions
1. The presence of beach marks shows fatigue as a major factor in the failure;
relatively small areas of crack propagation zone indicate a short service life.
∘
2. Steel 350w is unable to withstand −20 C temperature.
