HIC TEST ..Different result for the same Heat Number?

[dreamschool]

I noticed failures for some heat number ,,,and when we re-rest another plate from the the same heat ...some times it pass the test!!

Can we have different result for the same heat number for HIC test.

we used sloution A and the same procedure !!! Can i have answer for my concer and explination about how these result can be different from test to another

Regards

 

[dreamschool]

One more thing, the cemical compostion test is OK...sulfur is less than 0.01!!!!

 

[dreamschool]

Always the plate passes the HIC...after forming the pipe and take sample from the pipe and conduct HIC test...it failed...

it is strange for me ...i could not understand this...any explination???

 

[MetalMickey]

You can have failures and passes from the same heat I'm afraid. It suggests the material is near the threshold of resistance to this kind of phenomenon.
Suggest you examine the failures to see what the HIC damage is associated, i.e. is it sulphide inclusions, or microstructural variation, these will influence the test result.

The level of residual stress you have imparted into the item in forming plate to pipe will also have a detrimental effect on the HIC resistance of the material.