The effects of heat treatments on the nodular corrosion resistance of Zircaloy-4 have been investigated in the super-heat steam of 500 ℃ and 10.3 MPa by autoclave tests. It is found that the nodular corrosion resistances are obviously different for the specimens heat treated at 600 ℃, 820 ℃ and 1000 ℃, respectively. The key factors improving the nodular corrosion resistance are the supersaturated solid solution contents of Fe and Cr alloying elements in α-Zr matrix, but the size of the second phase particle...