摘要
通过多尺度试验表征与有限元模拟,系统研究了激光重熔镍基高温合金的微观组织演化、力学性能失配及其对疲劳性能的影响机制。基于纳米压痕测试与疲劳试验,结合改进的压痕反演算法,量化了重熔区、重熔影响区及基材的力学参数空间分布。结果表明,重熔区因非平衡凝固形成粗大柱状晶与Laves相,导致其强度显著低于基材,但枝晶– 胞状亚结构通过晶界钉扎作用抑制了宏观性能各向异性;重熔影响区虽存在高位错密度与孪晶界增殖,但是残余拉应力导致其名义硬度测量值低于真实性能;疲劳分析揭示了非均质材料中的应力屏蔽效应,即高应力水平下重熔区的循环软化与平均应力松弛显著降低裂纹驱动力,使疲劳失效转移至基材。本研究为激光修复构件的性能调控提供了跨尺度理论框架。
This study systematically investigated the microstructural evolution,mechanical property mismatch,and their effects on fatigue performance in laser-remelted nickel-based superalloys through multiscale experimental characterization and finite element simulations.By combining nanoindentation tests,fatigue experiments,and an improved indentation inverse analysis algorithm,the spatial distribution of mechanical parameters in the remelting zone(RZ),remelting-affected zone(RAZ),and base material(BM)was quantified.The results demonstrate that the RZ,characterized by coarse columnar grains and Laves phase formation due to non-equilibrium solidification,exhibits significantly reduced strength compared to the BM.However,dendritic-cellular substructures within the RZ mitigate macroscopic performance anisotropy through grain boundary pinning effects.Although the RAZ shows elevated geometrically necessary dislocation(GND)density and twin boundary proliferation,residual tensile stresses lead to underestimated nominal hardness measurements.Fatigue analysis reveals a stress shielding effect in the heterogeneous material system:cyclic softening and mean stress relaxation in the RZ under high-stress conditions substantially reduce crack driving forces,shifting fatigue failure initiation to the BM.This work establishes a cross-scale theoretical framework for optimizing the performance of laser-repaired components.
作者
张廷连
袁荒
ZHANG Tinglian;YUAN Huang(School of Aerospace Engineering,Tsinghua University,Beijing 100084,China;Institute for Aero Engines,Tsinghua University,Beijing 100084,China)
出处
《航空制造技术》
北大核心
2025年第11期34-43,81,共11页
Aeronautical Manufacturing Technology
基金
国家自然科学基金(92160204)
国家科技重大专项(HT-J2022-IV-0011-0025)。
关键词
激光重熔
强度失配
屏蔽效应
疲劳性能
镍基高温合金
Laser remelting
Strength mismatching
Shielding effect
Fatigue performance
Nickel-based superalloy
作者简介
张廷连,博士后,研究方向为高温材料结构强度理论和完整性评估;通信作者:袁荒,教授,博士生导师,主要研究方向为高温材料结构损伤力学、断裂力学和疲劳。
