ion55Parent Nuclides. Direct parent isotope is: 55 Co. Formation. 55 Fe can be artificially produced by neutron irradiation of stable iron isotopes: 54 Fe(n,γ) 55 Fe or 56 Fe(n,2n) 55 Fe. Accordingly, iron-containing components such as steelIron-55 (55 Fe) is a radioactive isotope of iron with a nucleus containing 26 protons and 29 neutrons.It decays by electron capture to manganese-55 and this process has a half-life of