Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy. The novel hole cold expansion technique introduced in this work involves the laser texturing process (LTP) followed by the Hertz contact rotary expansion process (HCREP), where the cylindrical sleeve is the critical component connecting the above-mentioned two processes. The purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface, preparing for the following HCREP. Hereafter, the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel tools. As compared to the as-received GH4169 material, the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains, higher micro-hardness, deeper compressive residual stress (CRS) distribution and lower surface roughness is formed at the hole wall. In addition, transmission electron microscope (TEM) observations reveal the microstructure evolution mechanism in the strengthened hole. Grain refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity, where the aggregated dislocations and recombined dislocation walls can be clearly observed.

孔壁周围优选的表面完整性是确保镍基高温合金孔组件最佳性能的关键参数之一。在这项工作中引入的新型孔冷膨胀技术涉及激光织构工艺（LTP），然后是赫兹接触旋转膨胀工艺（HCREP），其中圆柱形套筒是连接上述两个过程的关键部件。LTP的目的是获得最优化的强化圆柱套筒表面，为随后的HCREP做准备。此后，HCREP通过加强的套筒和圆锥形芯棒工具的旋转挤压运动作用在镍基孔组件上。与原样的GH4169材料相比，强化孔的表面完整性表征表明，在孔壁上形成了具有更细晶粒，更高的显微硬度，更深的压缩残余应力（CRS）分布和更低的表面粗糙度的塑性变形层。此外，透射电镜（TEM）观察揭示了强化孔中的微观结构演变机理。孔壁附近的晶粒细化被认为是改善表面完整性的根本原因，在此可以清楚地观察到聚集的位错和复合的位错壁。透射电子显微镜（TEM）观察揭示了强化孔中的微观结构演变机理。孔壁附近的晶粒细化被认为是改善表面完整性的根本原因，在此可以清楚地观察到聚集的位错和复合的位错壁。透射电子显微镜（TEM）观察揭示了强化孔中的微观结构演变机理。孔壁附近的晶粒细化被认为是改善表面完整性的根本原因，在此可以清楚地观察到聚集的位错和复合的位错壁。