Abstract: This paper proposes a new process for strengthening components made of high-temperature alloys that contain holes. The process is called the Multi-annular Convex Hull Rotating Cold Expansion Process (MCR-CEP) and is aimed at improving the fatigue life of nickel-based superalloys with hole-containing structures. In order to optimize the enhancement effect of the MCR-CEP process, various tests were set to analyze the impact of three process parame-ters on the surface integrity of the inner wall of the strengthened hole. Three process parameters contain the bump spacing, the spindle speed, and the expansion volume. Based on the test results, it was determined that the wider the bump spacing and spindle speed are, the smaller the squeezing force is; the larger squeezing volume is likely to cause an increase in the roughness of the inner wall of the hole and the saturation of the residual stress. After taking into account factors such as expansion pressure, microhardness, surface roughness, and residual stress, it has been determined that the optimal expansion parameters are as follows: a spacing of 0.8 mm for the expansion tool, a spin-dle speed of 100 revolutions per minute, and an expansion volume of 0.2 mm. Based on the results obtained, the av-erage fatigue life of specimens that underwent the MCR-CEP process showed an improvement of at least 118% com-pared with the un-strengthened hole structure. Moreover, the fatigue life of specimens that were processed using the optimal process parameters increased by 173%.

Key words: GH4169, orthogonal test, hole expansion, surface integrity, fatigue life