When low-silicon iron solidifies in the presence of nanosecond electromagnetic pulses, the influence of the irradiation time on the process is considered, as well as its influence on the structure and properties (hardness, density, local microhardness, corrosion resistance, and wear resistance) of the gray iron that forms. Extending the irradiation time increases the initial temperature of austenite solidification and reduces the eutectic and eutectoidal transformation temperatures. The dependences of the iron’s physicomechanical properties on the irradiation time include maxima or minima in the range 10–15 min. For example, the thermal conductivity doubles in that range.