Fracture in A356 T6 alloy 1

[trytrue]

Our customer returned a casting fractured in the field.
Very close to the fracture, there is a dent.
Is there any way to determine the impact load base on the dent dimensions (area and depth)?.
The part is made in A356 T6 aluminum alloy.

Any comments or leads we will appreciate.

 

[israelkk]

You can calculate the energy.
Depth*area*Ultimate_strengrh = energy

 

[Salvatio]

Is the temperature during fracture within the service temperature?
Different temperature may give different fracture load..

 

[etch]

This reminds me of a casting returned to us after fracture. We produced these castings and the engineer and die deisgner failed to put a small radius on an edle giving the casting a stress raiser.

the casting was returned to me with a clear fracture along this radius and 13 or 14 crescant dents along the face. after investigation and talking to the customer manager. I found out that it failed because it was attacked with a 5 lb hammer repeatedly until it broke.

Suffice to say i was not amused.

p.s the reason it was assaullted was to see how long it would be before it broke......it passed....

 

[trytrue]

FYI. The fracture and metallographic analysis found that the fracture happened due to foundry defect (cold lap 60% of the cross section) and the dent was caused after the fracture.
Your comments and answer helped to find the root cause.
Thanks

 

[Nadimuthu]

I would suggest that you look into the reasons for the cold lap first.This can cause discontinuity in the casting thicknes and load will not be carried in this area(Static as well as dynamic) and could be the reason for the failure.As the material yielded at this area, it could have fouled with some part of the assembly causing the dent.
A clear Cause-Effect diagram would lead you to the correct cause and thereafter to the solution.

Regards,
Nadimuthu