Jon Danniken wrote:

I recently purchased some (metric) bolts to attach a receiver hitch to my
Jeep. While the factory doesn't specify the grade, the nuts they go into
have a six (or possibly a 60) on them.

I didn't purchase the bolts from the stealership, because they want $11.00
(eleven dollars) *per* bolt, so I bought them from Fastenal instead.

When I bought the bolts, I got them in a grade 10.9 (metric).

Earlier today, I came across a discussion on a Jeep forum where someone
alluded to their belief that higher grade bolts would be too "brittle" for
this application.

Personally, I think I'm going to be just fine, but I know someone here will
have something more substantial than my gut feeling.

So, do you think I should order some different bolts, or will I likely be
just fine with the ones I already have?

Yes. In general, as you increase the yield stress of steel by alloying
there is a reduction in its ductility. This causes a reduction in the
fracture toughness (the amount of energy required to turn a small crack
into a large one), which manifests itself as increased brittleness.

However, it's much harder to say how much the brittleness will increase.
It may or may not be significant in your case.

You could try bending one of the bolts if they are of a fairly small
diameter. If you can make a large bend in the bolt before it breaks the
brittleness probably isn't going to matter.

Best wishes,

Chris