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本文用金相显微镜和扫描电镜对 Ti-5Al-2.5Sn 合金在近中性3.5%NaCl 水溶液中 SCC 裂纹形核带的微观形貌进行了观察。通过金相显微镜、透射电镜、X 光衍射仪和离子探针等手段对 SCC断口的研究,证明了 SCC 裂纹尖端生成的氢确实进入了钛合金基体,并且裂纹前端最大三向应力区域形成了 fct 型和 bcc 型氢化物沉淀,导致了 SCC 的快速发展。在实验事实的基础上,对 SCC 过程中氢的来源、输运、氢起作用的位置,以及内氢的作用等问题进行了讨论。
In this paper, the microstructure of Ti-5Al-2.5Sn alloy in SCN crack nucleation zone in near-neutral 3.5% NaCl aqueous solution was observed by optical microscope and scanning electron microscope. The study on the fracture of SCC by means of metallographic microscope, transmission electron microscope, X-ray diffractometer and ion probe proved that the hydrogen generated at the crack tip of SCC did enter the titanium alloy matrix and the maximum three-stress region in the front of the crack formed fct Type and bcc type hydride precipitation, led to the rapid development of SCC. On the basis of the experimental facts, the problems of the source and transport of hydrogen in hydrogen, the location of hydrogen activation and the role of hydrogen in the SCC process are discussed.