热等静压作用下镍基高温合金蠕变空洞愈合机理及动力学研究

项目名称： 热等静压作用下镍基高温合金蠕变空洞愈合机理及动力学研究

项目编号： No.51301001

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 一般工业技术

项目作者： 周煜

作者单位： 安徽工业大学

项目金额： 25万元

中文摘要： 热等静压恢复技术能够愈合发动机关键热端部件在服役过程中产生的蠕变损伤，延长其使用寿命。最佳的热等静压工艺参数通常是根据大量的试验数据和工程经验获得，而蠕变空洞在热等静压作用下的愈合机理及动力学研究可以更好地指导工艺参数的优化。本项目以发动机用镍基高温合金K465为研究对象，从热等静压温度、压力和保持时间对蠕变空洞愈合行为的影响规律的试验研究入手，采用微观组织分析手段和蠕变空洞附近的应力应变场分析对愈合时出现的同心γ'筏化结构作深入研究，揭示蠕变空洞在热等静压作用下愈合的物理机制。基于材料热力学理论建立在应力和扩散耦合作用下蠕变空洞的愈合动力学模型，完成热等静压温度和等静压力对空洞愈合动力学影响的参数分析，构建热等静压愈合图。考虑空洞形貌及尺寸分布特点，采用有限元方法模拟蠕变空洞在热等静压作用下的演变过程，为热等静压工艺参数的优化提供理论基础，进而为发动机热端部件延寿技术的发展提供科学依据。

中文关键词： 热等静压；高温合金；蠕变空洞；愈合机理；动力学模型

英文摘要： Hot isostatic pressing (HIP) rejuvenation technology can be utilized to heal the service-exposed creep damages of the critical hot section components in turbine engines, in order to extend the service life. The optimal HIP parameters are generally determined from a large amount of experimental data and engineering experience, but the investigation on the healing mechanism and kinetics of creep cavities under HIP can provide better guidance for optimizing HIP parameters. In this project, a nickel-based superalloy K465 widely used in engines is selected, and the experimental studies of the influences of HIP temperature, hydrostatic pressure and soaking time on the healing behavior of creep cavities are initially conducted. The formation of the concentrically-oriented γ' rafting structure is further investigated through the microstructural analysis and the stress-strain field in the vicinity of the creep cavity, in order to reveal the physical mechanism of cavity healing for nickel-based superalloys under HIP. The healing kinetics model for creep cavities under the coupling effect of stress and diffusion is then established based on the thermodynamics theory. The parametric analysis for the effects of HIP temperature and hydrostatic pressure on the healing kinetics is accomplished, constructing the HIP healing map.

英文关键词： hot isostatic pressing；superalloy；creep cavity；healing mechanism；kinetic model