reaction of metals

K, Na, Ca are very reactive metals. They can react with cold water.
Therefore, they can certainly react with steam vigorously which is dangerous.
For reaction between Zn and steam, Zinc oxide and hydrogen gas will be formed. Zinc oxide is in white powder form and insoluble in water. Hydrogen gas gives a pop sound on burning splint
For reaction between Fe and steam, iron oxide and hydrogen gas will be formed. The iron oxide form is iron (III) oxide which is red-brown in colour and insoluble in water.
The reaction between iron and steam is reversible.