Electroplating and Electroless-Plating of High-Strength Steels from the Point of View of Their Hydrogen Embrittlement

摘要

Study of silver, cadmium sulphamate-nickel, hard chromium and electroless nickel on steels showed: with suitable pretreatment of the base material before plating, the material absorbs no hydrogen. The greater the strength of the material, the more hydrogen it absorbs given the same hydrogen supply during plating. In the case of sulphamate-nickel plating and silver plating, there is practically no hydrogen absorption, while in the case of electroless-nickel plating moderate hydrogen absorption takes place in the substrate. Cadmium plating and hard chromium-plating show clear evidence of hydrogen absorption in the base material. A combination of sulphamate-nickel and hard chromium reduces the hydrogen absorption by the substrate connected with hard chromium plating. All coatings absorb hydrogen, the most by hard chromium and cadmium, the least by sulphamate-nickel. The hydrogen from the hard chromium-plated substrate can be removed easily by heat treatment. Degassing of hydrogen from cadmium-plated substrates is more difficult. The relationship between hydrogen content and embrittlement in high-strength steels can be recorded. Case-hardened steels as well as gas-nitrided steels can be hard chromium-plated in combination with a suitable heat treatment for degassing the hydrogen. 27 figures. (ERA citation 08:046816)