Chevron marks in copper alloy?

[GonzaloMartinez]

Hello everyone,

I have this fractured copper alloy shaft that shows what looks to me as chevron marks pointing to a single iniciation site. On SEM examination the mode of fracture observed was ductile overload. I have always associated chevron marks to brittle fracture. Is it possible to see this macro characteristic in the presence of a ductile fracture mechanism? Maybe I'm missing something here?

Best regards,
Gonzalo.

 

[EdStainless]

The high mag sure look fully ductile.
The texture in the macro could be related to either the loading (just because it is ductile failure does not mean that it failed in a single overload) or the grain texture of the material.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

The radial ridges (not chevron markings) on the fracture surface emanate from the OD surface as you described. Definitely ductile failure based on the dimpled (cup/cone) appearance in the last two SEM images. Chevron markings are shaped like arrows.

 

[mrfailure]

This is more of a terminology issue. I prefer to use the term river marks, which indeed point to the first location where your ductile overload fracture started (every fracture has to start somewhere). I usually use the term chevron marks on fractures that occur on longitudinal planes. They are indicative of rapid overload fracture and usually, but not always, are associated with brittle fracture (a mod more likely to induce rapid overload).

 

[GonzaloMartinez]

Thank you EdStainless, matengr, mrfailure! It is always enlightening to read your answers.