高温高压水环境中690 TT传热管冲切双轴微动磨蚀过程中的微观组织演变

Microstructure Evolution of 690 TT Heat Transfer Tube Under Impact Slip Dual-Axis Fretting Corrosion in High Temperature and High Pressure Water Environment

摘要:

模拟压水堆蒸汽发生器传热管在高温高压水环境下服役，采用690 TT合金管和405 SS板组成的摩擦副进行冲切双轴微动磨蚀实验，研究了冲切微动磨蚀过程中690 TT管的微观组织演变过程。采用白光干涉仪、扫描电子显微镜、透射电子显微镜和拉曼光谱等分析手段对磨蚀表面及近表面的微观组织和磨蚀产物进行探究。结果表明：在10⁵次循环以内，690 TT合金的磨损机制主要为伴随材料转移的粘着磨损；5×10⁵至2×10⁶次循环下，690 TT合金的磨损机制主要为裂纹萌生、扩展和分层脱落。微观组织演变方面，10⁵次循环的样品截面微观形貌中，三体层下存在混合层；5×10⁵和2×10⁶次循环的样品截面微观形貌区别不大，具有厚度约为500 nm的摩擦转化结构层，微观组织演变进入稳定阶段。

Abstract:

The service water environment of high temperature and high pressure was simulated for the steam generator heat transfer tube of pressurized water reactor. 690 TT alloy tube and 405 SS plate were used to form the friction pair for impact slip dual-axis fretting corrosion experiments. The microstructure evolution of 690 TT alloy tube during dual-axis impact slip fretting corrosion was investigated. White light interferometer, scanning electron microscope, transmission electron microscope, and Raman spectrum were used to investigate the microstructure and abrasive products of the abraded surface and near-surface. Results indicate that within 10⁵ cycles, the wear mechanism of 690 TT alloy tube is mainly adhesive wear accompanied by material transfer. With the increase in cycles from 5×10⁵ to 2×10⁶, the wear mechanism of 690 TT alloy tube is mainly crack initiation, propagation, and delamination. In terms of microstructure evolution, mixed layer exists under the three body layer in the cross-section microstructure of samples after 10⁵ cycles. The microstructures of samples after 5×10⁵ and 2×10⁶ cycles show slight difference and present a tribological transfer structure layer with thickness of about 500 nm. Additionally, the microstructure evolution enters the stable stage.