ISSN   1004-0595

CN  62-1224/O4

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2种Zr(-Sn)-Nb合金与316L不锈钢的冲击磨损性能

Impact Wear Properties of Two Zr(-Sn)-Nb Zirconium Alloys with 316L Stainless Steel

  • 摘要: 采用316L不锈钢材质的锐角圆锥块作为摩擦对偶,在硼酸锂的液流条件下对2种Zr(-Sn)-Nb合金管进行不同循环次数(N =102,103,104,105,106)的冲击试验. 模拟了锆合金包壳在异物磨蚀情况下的冲击状态,研究了2种Zr(-Sn)-Nb合金管的冲击磨损性能及冲击磨损机制. 结果表明,锆合金管材在冲击磨损作用下的磨损机制主要为塑性变形和疲劳剥落. 机械性能、动力学曲线和冲击磨损试验等数据皆表明,Zr-Sn-Nb合金拥有比Zr-Nb合金更好的抵抗316L不锈钢冲击磨损的能力. 磨痕边缘材料塑性流动导致的裂纹形成与扩展及磨痕底部裂纹延伸交汇后发生的疲劳剥落,都会对锆合金管造成严重的磨损去除. 冲击过程中,锆合金管与摩擦对偶会发生材料迁移,形成Zr、O、C、Fe元素不均匀分布的磨屑堆积层.

     

    Abstract: The fuel element cladding serves as the first and most important safety barrier against the release of radioactive products into the environment in a pressurized water reactor (PWR). The loss of its integrity will not only bring huge economic losses, but also lead to major security threats. Therefore, improving the reliability of fuel and maintaining the integrity of nuclear fuel cladding is of great significance to the operation and long-term development of nuclear power. In the pressurized water reactor nuclear power plant, the debris constantly rubs and collides with the fuel rods under the continuous scouring of the coolant, resulting in the wear of the fuel rods and even the leakage of perforations. In this paper, two kinds of Zr(-Sn)-Nb zirconium alloy tubes were impacted by a 60° acute angle conical block of 316L stainless steel with an impact energy of 4.0 mJ for different cycles (N =102, 103, 104, 105, 106). 1 200 mg/L H3BO3+2.2 mg/L LiOH solution was flowed over the impingement contact surface at a flow rate of 10 mL/min. The impact wear behavior of zirconium alloy cladding under debris-induced fretting wear was simulated. After that, the dynamic response of the force, velocity and energy during the impact test was obtained by analyzing the data collected by the impact wear tester. Optical microscope, 3D morphology and scanning electron microscope were used to observe the surface and cross-sectional micro-morphology of the wear scars and measure the wear depth and wear volume. Combined with the analysis of wear debris components obtained by energy spectrometer, the impact wear performance and impact wear mechanism of two zirconium alloy tubes were studied. Before the impact wear test, the results of nano-indentation and ring compression test showed that Zr-Sn-Nb zirconium alloy had higher hardness and elastic modulus than Zr-Nb zirconium alloy, and was more compressive. The dynamic response of impact wear showed that the contact peak force and energy loss of Zr-Sn-Nb zirconium alloys were higher than those of Zr-Nb zirconium alloys. The impact wear test results showed that the wear depth and wear volume of Zr-Sn-Nb zirconium alloys were higher than those of Zr-Nb zirconium alloys. After 105 cycles of impact, the wear area of the Zr-Nb zirconium alloy tube increased significantly, which was mainly due to the wear of the friction pair. When impacted with 316L stainless steel, the energy consumption of Zr-Nb zirconium alloy during impact was more, and the wear of zirconium alloy tube was more serious; The relative deformation between Zr-Sn-Nb zirconium alloy and 316L stainless steel impact block was larger, but the damage of the zirconium alloy tube itself was small. The results showed that the wear mechanisms of the two zirconium alloy pipes under impact wear were mainly plastic deformation and fatigue spalling. In the process of impact wear, the work hardening caused by the impact can effectively reduce the wear rate of the material. However, with the increased of the cycle of impacts: The plastic flow of the material at the edge of the wear scar leaded to the initiation and propagation of cracks to the zirconium alloy matrix; The extension and intersection of fatigue cracks at the center of the wear scar will cause fatigue spalling of the material, resulting in more serious wear and removal. Zr-Sn-Nb zirconium alloy had better resistance to impact wear of 316L stainless steel than Zr-Nb zirconium alloy. During the impact process, material migration occurred between the zirconium alloy tube and the friction pair, forming a wear debris accumulation layer with uneven distribution of Zr, O, C, and Fe elements.

     

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