ZnNi – Beschichtung hochfester Bauteile aus Stahl

ZnNi – Plating of high strength steel components Pre‐treatment and electroplating as well as post‐plating treatment of especially low alloyed high tensile strength steel components can be followed by a delayed hydrogen‐induced fracture known as hydrogen embrittlement. The entire coating process has to be controlled to avoid any failure. Most important is, that atomic hydrogen being evolved during the coating process and penetrating into the base metal after all shows an subcritical concentration within the system with respect to the mechanism of hydrogen embrittlement. Generally this will be obtained by a suitable post‐plating heat treatment of the coated components. There is evidence however that under special conditions for ZnNi – plating from alkaline solution this is not necessary. Results are reported concerning the nucleation and crystal growth and the hydrogen diffusion through ZnNi‐deposits. Further on hydrogen depth profiles of coated components and their mechanical properties will be presented and discussed.