When sourcing Armco Iron, the primary focus must be on chemical purity and magnetic properties. You should ensure the Carbon content is extremely low (typically <0.02%) to maximize magnetic permeability. Key specifications include coercivity (Hc), which should be as low as possible for electromagnetic applications, and saturation induction (Bs). For high-precision components, verify the grain size and non-metallic inclusion levels, as these directly impact the material's performance in DC magnetic circuits and relays.