What causes exhaust manifold bolts to break? on 2008 Ford F-150

Does a warped exhaust manifold cause the bolts to break or does the bolts breaking cause the manifold to warp? We are have an issue with the warranty department.

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2 answers 2 comments
Defective materials or improper assembly.
Wonder what motor this thing has?
It's a gasoline/green jelly hybrid I believe.......never mind....
repeated heating and cooling