Is iron/steel magnetic at temperatures over their melting point? I have an idea, but it will only work if ferrous materials retain magnetic properties in a liquid state.
Melting temperature of iron : 1811 K
Currie temperature of iron : 1043 K
From wikipedia:
"When the temperature rises beyond a certain point, called the Curie temperature, there is a second-order phase transition and the system can no longer maintain a spontaneous magnetization, although it still responds paramagnetically to an external field."