Embrittlement of high strength steel components, like threaded fasteners, that have been plated with cadmium or zinc most often occurs due to the phenomenon known as Hydrogen Embrittlement.  Hydrogen is produced in various processes (acid cleaning/pickling, electroplating baths) and absorbed into the steel.  The hydrogen diffuses to areas of high tensile stress, which can then produce brittle failures at stresses considerably below the materials' yield or tensile strength.

Hot-dip galvanizing eliminates the hydrogen embrittlement concern, but Liquid Metal Embrittlement may still pose a problem.  LME of ferritic steels has been reported in the temperature range of 400-620 C (750-1150 F).  LME due to cadmium, which is a more potent embrittler than lead, tin, zinc, or indium, has been identified in the temperature range of 170-321 C (338-610 F).

Embrittlement of ferritic steels in contact with solid zinc has been reported (as delayed fracture) at temperatures ~ 400 C (750 F), which is just below the melting point of zinc.

If as TVP states Acid Pickling creates Hydrogen Embrittlement, then this can occur during the Galvanising
process, as part of the preparation for galvanising is to
Acid Pickle items prior to Galvanising, especially smaller delicate items like Nuts, Bolts, Threaded Stud Bar etc.
We here specify that High Strength Bolts be supplied as ungalvanised, due to embrittlement possibilities. Our standard for Lower Strength bolts require them to have been 'Spun Galvanised' which reduces the risk.

Entrapped nacent Hydrogen either from pickling or plating can be driven off by baking at 350-400F for 3-24 hrs.  If pickling, the parts should be baked after pickling and before any other operation.  The shorter baking time is adequate for parts below 220,000 psi UTS whereas longer baking time is required for higher strength parts.  Elapsed time between plating and baking must not exceed 8 hr.

QQ-P-416 TYPE II CLASS 2 covers Cad plating but possibly also includes Galvanizing.

Jesus is The TRUTH

Does galvanizing studs affect the tensile strengh below 100F?? or say 200F???

Galvanizing will not affect the nominal tensile strength of a steel component.