What’s the difference between A36 and F1554-36?

ASTM A36 is a material specification for carbon structural steel. ASTM  F1554-36 is fastener specification.  The two most common fastener specifications for carbon steel threaded rod are ASTM A307A and ASTM F1554-36.  Both require that the threaded rod or stud meet the minimum tensile requirements of A36.  Each specification may require additional testing.  Please refer to each specification for specific requirements.