Cadmium embrittlement falls into to the category liquid metal embrittlement where the lower melting point metals diffuse into the the base material forming intermetallic compounds, thus intergranular failure. Since the process is caused by diffusion the temperature is an important factor, as well as tensile stresses to allow the diffusion.
The failures can sometimes by mistake be taken as stress corrosion cracking or hydrogen cracking.
To prevent the Cadmium from coming in contact with the steel, the bolts can be coated with a thin layer of Ni before the Ca treatment. However, experience shows that the quality of equipment, procedures and operators of the plating facilities are not sufficient for high quality products. Thus NiCa plating is often not recommended for several applications.
Parent Directory 16-Feb-1999 15:44 -