Xin Long, Kang Lanzheng, Bian Weiwei, Zhang Mengyang, Jiang Qinglei, Shoji Tetsuo
National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China.
China Nuclear Power Operation Technology Corporation, Ltd., Wuhan 430223, China.
Materials (Basel). 2021 Oct 2;14(19):5778. doi: 10.3390/ma14195778.
The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30-60 μm in nitrogen. Fretting-induced wear won the competition at 45-90 μm in air but at 75-90 μm in nitrogen.
详细研究了位移幅值对690合金在空气和氮气气氛中的微动磨损行为及损伤机制的影响。结果表明，在空气中，摩擦系数随位移幅值的增加而逐渐增大，符合普遍规律。然而，在氮气中，由于极强的附着力，在位移幅值为60μm时摩擦系数出现最高点。无论在空气中还是氮气中，磨损体积均随位移幅值的增加而逐渐增大。除30μm外，空气中的磨损体积大于氮气中的磨损体积。在30μm时，空气中的磨损体积略小。随着位移幅值的增加，微动运行状态从部分滑移、混合黏滑最终到完全滑移发生转变，同时Ft-D曲线从线性变为椭圆形，最终变为平行四边形。相应地，微动区域从部分滑移区域转变为混合区域再到完全滑移区域。随着位移幅值的增加，由于还原环境中低氧含量引发的强附着力，氮气中从部分滑移到完全滑移的转变比空气中延迟。无论在空气中还是氮气中，微动诱发疲劳与微动磨损之间的竞争关系都很突出。裂纹扩展速度比磨损速度更快。在空气中，30μm时微动诱发疲劳占主导，但在氮气中为30 - 60μm。在空气中，45 - 90μm时微动磨损占优，但在氮气中为75 - 90μm。
