I want to weld a nut on the door hinge but I'm afraid it may be cast iron.
Anybody knows for sure if the door hinges are cast or forged?
Please reply only if you know for sure.

 

seems like a bad place to use cast but very well could be. You could always do the grinder spark test.

 

Glad you asked and posted a pic. Good question.
My 2 bets would be: multi-stage process-stamped 2 part tack welded assembly of thin plate metal.
: cast steel

Before I'd use a grinder and cause damage you'd be better off to start with a good strong magnet test. And noa fridge magnet advertisement doesn't count. Use one on the end of a small screwdriver head (not bit holding tip). Good attraction contact is what you're looking for to do a fairly normal type of weld on a home model weld m/c.
No attraction and you may be getting in over your head to do the weld yourself. eg aluminum but that's the material on the door side of the hinge. Cast iron .....NOT...just look at the suface texture. neither would attract a good magnet.
Just by asking the question in the first place I'd say you might want to take it to Joe's weld shop down the road to get advice. The part's already off and if you get there around lunch time they'll be glad to help. And for you showing up not sounding like you know it all they might even weld it up for free.

 

It doesn't look stamped or 2 part tack welded assembly.
This is a side view of it.



There are these grooves on the back of it that suggest casting.

 

Are you adding the nut for a mirror when doorless? Is the bracket thick enough to drill and tap it vs. welding a nut to it?

 

Asked my buddy who is a Jeep engineer and he said the hinges are aluminum. Double check with the magnet test though.

Edit: he said they are aluminum so they don't rust when they chip (hinges are known for getting chips).

 

It's for a jerrycan mount. a weldnut will be stronger.
You welcome to steal my idea.

 

Your buddy is right for the door side of the hinge, the body side of the hinge is steel.

 

just fyi...

https://www.youtube.com/watch?v=D094eBa4S7c

 

Come on we're waiting...what did the magnet say. I SEE SPARKS EVERY TIME i GET UP FAST FROM THE COUCH.
Those hinge parts rust...not aluminum...not cast iron..bright red runny rust found in sheet plate or cast steel.
Refer to pics of Titanic Luke.
But then again if you have a spare hinge you aren't going to reuse on the Jeep go with the spark test. The test one will be...well...obviously...tested. And don't forget to dress/clean the wheel after test. Oh and make sure the grinder RPM........

Jerry can on door hinge.......Priceless...my Pepsi just blew out my nose...it hurts...
AND I wasted time on....