Not sure if this helps. I have included an attachment regarding fatigue on cast iron. https://files.engineering.com/getfile.aspx?folder=10e60adf-1dde-4dd6-b422-654e3c013d73&file=Ahmad_ICRS-10_Bendingfatiguebehaviourofblastcleanedgreycastiron_(1).pdf
Chrome over nitride surfaces can be easily achieved but removal of the "white layer" first. The nitrogen layer is non-conductive. You cannot nitride after chrome and expect positive results since the ions will bounce off the surface of the chrome and not penetrate the substructure. I came across...
