Cl-SCC Inter or Trangular?

[ronfrend]

API 571 describes Chloride Stress Corrosion Cracking as being Interganular whereas most sources indicate it is Transgranular.

Which is true or do both types occur in real life?

Ron Frend

http://www.predicon.net

 

[SJones]

My copy of 571, subclause 4.5.1.5, item d) states:

Metallography of cracked samples typically shows branched transgranular cracks. Sometimes intergranular cracking of sensitised 300 Series SS may also be seen

It shows that both types can occur in real life with factors such as microstructure, stress and corrodent serving to drive whether initiation is from pitting or from intergranular corrosion and whether cracking propagates through a transgranular, intergranular, or even a mixed mode.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04