Grey cast iron valve fracture

[Gerardcreep]

I need to get information regarding fracture appearance of overstressed grey cast iron. There are some intergranular fracture visible on the inside of the cast and almost looks like cup cone fracture on the outside. I do also need some inhibuted acid that will clean the fracture surface of this cast iron?

Please any suggstions would be appreciated.

Thank you

 

[arunmrao]

If the material is cast iron cup and cone fracture phenomenon is not possible It happens only in ductile material.

 

[MOB1]

Gray cast iron is classified as a brittle material as it shows little or nil ductility in a tensile test (as measured by elongation or reduction of area).
Fractures by most mechanisms occur along the graphite flakes in a "brittle" manner. This normally means that there is no ductility evident.
To clean fracture faces try 50% phosphoric acid swabbed on the surface and washed after sufficient time with water. The usual safety precautions for using concentrated acids must be followed.

 

[SMF1964]

The intergranular fracture features in the center is the brittle fracture along the graphite flakes. The "cup & cone" fracture on the outside of the sample could be the normal overload mechanism of the decarburized surface layer - how wide is the "cup cone" layer/region?

a 10% solution of hydrochloric acid inhibited with one of the Rodine inhibitors (I use 426 for steels) works quite well.