Brian,
A great source of information is the ASTM standard on hot dip galvanized coatings. I have a copy of an old standards from 1977. One of the standards is ASTM A 123, which is the standard for galvanized coatings on products fabricated from rolled, pressed, and forged steel shapes, plates, bars, and strip. Section 6 addresses steel embrittlement in general and states in part the following: "Steel that is cold worked may become embrittled, depending on such factors as the type (strength level, aging characteristics), thickness, and degree of cold work. Galvanizing may accelerate embrittlement. The tendency of embrittled steels to fail in a non-ductile manner is greater the lower the temperature at which the steel is used. Therefore precautions against embrittlement shall be taken by the designer, the fabricator, and the galvanizer". Also, ASTM A 143 is the standard for safeguarding against the embrittlement of hot dipped galvanized structural steel products and the procedure for detecting embrittlement. It states in part in 3.2: "In the case of galvanized steel, the acid pickling reaction prior to galvanizing presents a potential source of hydrogen. However, the heat of the galvanizing bath partially expels hydrogen which have been absorbed. In practice hydrogen embrittlement of galvanized steel is usually of concern only if the steel exceeds approximately 150 ksi (1100 MPa) in ultimate tensile strength, or if it has been severely cold worked prior to pickling." Also, in 6.1 it states: "Hydrogen can be absorbed during pickling and in some instances as noted in 3.2, may continue to contribute to embrittlement of the galvanized product. The liklihood of this, or of surface cracking occurring, is increased by excessive pickling temperatere, prolonged pickling time, and poor inhibition of the pickling acid. Heating to 300 degrees F after pickling and before galvanizing in most cases results in expulsion of hydrogen absorbed during pickling." I'd be happy to send you a copy of these two standards by fax if you don't have access to them.