随着汽轮机运行参数的提高，其叶片的服役环境也愈来愈严酷，这严重影响了汽轮机的运行稳定性及使用寿命。SP-700钛合金由于其良好的加工性和较低的生产成本被认为是汽轮机末级叶片的潜在替代材料。本项目以SP-700钛合金为研究对象，突破传统单一强化的思路，在合金表面进行双层辉光等离子渗Zr处理，获得表面强化层，并通过热处理工艺调控，获得能够在加载过程中产生应力诱发相变的组织结构。研究交变载荷下SP-700钛合金渗Zr层与应力诱发相变的协同作用机制及其对疲劳行为的影响，揭示表面强化与相变强化协同作用下SP-700钛合金的疲劳损伤机理，建立反映表面强化特征及微观相变效应的疲劳寿命预测模型，以期为SP-700钛合金叶片的设计及其在汽轮机中的应用提供科学依据，同时对丰富金属材料的疲劳理论体系具有重要意义。

With the higher standard of the operating parameters of the steam turbine, the service environment of the blade becomes more and more severe. SP-700 titanium alloy is considered to be a potential material for the last stage blade of steam turbine due to its good processability and low cost. This project takes SP-700 titanium alloy as the research material, breakthrough the limitation of traditional single strengthening methods, using the double glow plasma surface treatment to do Zr alloying on SP-700. Through the heat treatment control, the phase transformation during the loading will be introduced in this alloy. Under the fatigue loading, the synergistic mechanism of the surface layer and the stress induced phase transformation and their influence on the fatigue performance in SP-700 alloy will be investigated, the fatigue damage mechanism with the synergistic action of the surface strengthening and phase transformation strengthening will be revealed. A fatigue life prediction model with accurate parameters deduced from the surface layer and phase transformation will be developed. These research results will provide a scientific basis for the design of SP-700 titanium alloy blades and its application in steam turbines, at the same time, it is of great significance to enrich the theory of fatigue for metal materials.