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.
维普
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