Flat Head Socket Cap Yield
Flat Head Socket Cap Yield
(OP)
Anybody know where to find proof strength and yield strength (in psi) for inch size alloy steel button head and flat head socket cap screws? I spent a couple of unsuccessful hours searching on the Internet and in reference books, and talking to manufacturers and suppliers. Found ultimate tensile. Found proof, yield, and ultimate for regular socket caps. But could not find proof and yield for button head and flat head. If consistent with regular socket caps, specs will be higher for 1/2" dia and under than for over 1/2" dia.





RE: Flat Head Socket Cap Yield
What may limit the actual strength may
be the head design limitations.
Is that your question? I would hope that
the head design allows the max torque to
be applied without breaking off the head
of the bolts or screws.
RE: Flat Head Socket Cap Yield
That could be why you are not finding any data.
RE: Flat Head Socket Cap Yield
I too hope weak spot is thread size not head shape...we see more flat head now in structural applications (where visible for appearance I think) than earlier times. No rule against these of I know...
RE: Flat Head Socket Cap Yield
DC
RE: Flat Head Socket Cap Yield
I realize that the head is the weak link in flat head and button head screws.
Diamondjim - I would have agreed with what you said until I found concrete information to the contrary. Material ultimate tensile strengths are significantly lower for buttons and flats than for regular heads. For 1/2" dia and under, it's 180 ksi for regular heads and 145 ksi for buttons and flats.
Maybe yield is not specified for flats and buttons because it's a moot point - the head pops off before the shank or threads ever get to yield - and ultimate is specified just as a formality, or so a bolt can be compared against the spec with a hardness tester.
RE: Flat Head Socket Cap Yield
Look to ASTM F835 for more detail.
Here is a quote, "Fasteners meeting this specification are intended for shear type applications and have tensile requirements ranging from 122 to 150 ksi."
Dick
RE: Flat Head Socket Cap Yield
I wonder if this limitation would
hold up in court if someone
misapplied these screws.
Thanks for the ASTM F835 reference.
Gave you a star!
RE: Flat Head Socket Cap Yield
An old time engineer here always said, "you can have a low head or a strong head, but you can't have both; which do you want".