In order to optimize the corrosion resistance of domestic Zr-4 alloy, the effects of alloying element Fe+Cr and impurity element Si on the corrosion resistance of domestic Zr-4 alloy were studied under the accelerated corrosion condition of high temperature and high pressure steam at 420℃ and 10.3 MPa. The results show that within the range of Fe+Cr content specified by ASTM (0.28 wt%-0.37 wt%, with wt% representing mass percentage), the higher the Fe+Cr content, the larger the number and size of the precipitated second phases, which is beneficial to the improvement of the corrosion resistance of the material. When the content of Fe+Cr increases from 0.28 wt% to 0.37 wt%, the corrosion weight gain of Zr-4 alloy decreases by about 30% after 126 d of corrosion in steam at 420℃. When the Si content of Zr-4 alloy is as low as 10 mg/kg during quenching at 1100℃, the coarse parallel-plate structure is formed. When the Si content is increased to 100 mg/kg, the precipitated fine Zr3Si provides nucleation sites for α phase, which leads to the appearance of basketweave structure and fine parallel-plate structure in the microstructure. The basketweave structure can promote the distribution of the second phase in the structure to be more uniform and diffuse, so the Zr-4 alloy with high Si content shows better corrosion resistance. © 2024 Atomic Energy Press. All rights reserved.
