Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)
by Randy Taylor, Advanced Tooling Corporation
AISI 4340, 4130 etc., Thin Dense Chrome plating & Hydrogen Embrittelment
Q. After applying TDC is it necessery to bake it to avoid Hydrogen Embrittelment and if so are the parameters of the bake similar to Hard chrome plating, i.e. 375°F for 12hrs?
A. Yes, you must bake after TDC plating, especially if the base material is a ferrous alloy. The potential for embrittlement due to the interaction between atomic hydrogen and the ferrous metallic atomic structure, is the same in TDC as in standard hexavalent hard chrome plating. Bake parameters are established to affect a specific type of steel and tensile strength. As the strength of the steel goes up, so does its susceptibility to Hydrogen embrittlement. A 12 hr. bake at 375oF is required for low alloy, high strength steels 220 ksi (220,000 psi) and above.