Zr-2.5Nb压力管材的氧化腐蚀行为影响因素

Influence Factors of Corrosion Behavior of Zr-2.5Nb Pressure Tube

从Zr-2.5Nb压力管上切下3种具有不同取向的试样,在10 MPa和1 MPa的400℃高温蒸汽中进行氧化试验。采用各种微观观察技术对试样的形貌、成分和织构进行研究。结果表明:降低预膜处理工艺中的蒸汽压力并不会造成预生氧化膜的减薄,可以对预膜处理工艺中的蒸汽压力进行优化以取得更好的经济效益。取向对材料的腐蚀氧化有显著影响,端面(R-T面)较其余面的氧化速度更快。氧化后试样侧面(L-R面)出现条带状凹坑,这是β-Nb氧化脱落所致。低晶界密度、更紧凑的原子排列以及沿管子轴向拉长富Nb带都是造成管材侧面(L-R面)和曲面(L-T)具有更好耐蚀性的原因。

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 wasβ-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.