Influence Factors of Corrosion Behavior of Zr-2. 5Nb Pressure Tube

Three samples with different orientations were cut from Zr-2. 5Nb pressure pipe and subjected to oxidation tests in 400 ℃ high-temperature steam at 10 MPa and 1 MPa. The morphology, composition, and texture of the samples were studied using several micro observation techniques. The results indicated that reducing the steam pressure in the pre film treatment process did not cause thinning of the pre formed oxide film, and could optimize the steam pressure in the pre film treatment process to achieve better economic benefits. Orientation had a significant impact on the corrosion and oxidation of the samples, with the oxidation rate of the end face (R-T face) being faster than that of the other surfaces. After oxidation, strip shaped pits appeared on the side (L-R surface) of the sample, which was β- Caused by Nb oxidation and detachment. Low grain boundary density, more compact atomic arrangement, and elongation of Nb rich bands along the axial direction of the pipe were all reasons for high corrosion resistance on the side (L-R surface) and curved surface (L-T) of the pipe.