Investigation of the Internal Oxidation and Hot Rolling Deformation Behavior in Ni36

Abstract

The oxidation behavior of Ni36 was investigated through high-temperature oxidation experiments under air conditions at oxidation temperatures of 1000 °C and 1200 °C and oxidation times ranging from 0.5–3 h. A kinetic model for internal oxidation was established to elucidate the formation mechanism of the internal oxidation zone. The results indicate that the external scale consists of two layers: outer layer primarily composed of Fe₂O₃ and inner layer primarily comprising a mixture of Fe₃O₄ and NiO. The internal oxidation zone exhibits both intragranular and intergranular oxidation structures, intragranular oxidation primarily composed of Fe₃O₄ and FeO, intergranular oxidation predominantly consists of Fe oxides. At 1200 °C, the depth of the intragranular oxidation approaches that of the intergranular oxidation. Single-pass hot rolling experiments using wedge-shaped samples were conducted to study the effects of heating temperature and reduction ratio on the deformation behavior of the internal oxidation zone. The results show that cracks and holes in the internal oxidation zone decrease as the heating temperature increases. Furthermore, under the influence of tensile stress along the rolling direction, cracks and holes are more severe in the side surface compared to the rolled surface.