A novel hole cold-expansion method and its effect on surface integrity of nickel-based superalloy  

作　　者：XianCao Ping ZhangShuang Liu Xue-Lin Lei Run-Zi Wang Xian-Cheng Zhang Shan-Tung Tu 

机构地区：[1]Key Laboratory of Pressure Systems and Safety,Ministry of Education,School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China

出　　处：《Journal of Materials Science & Technology》2020年第24期129-137,共9页材料科学技术（英文版）

基　　金：sponsored by the National Key Research and Development Program of China(2018YFC1902404);the National Natural Science Foundation of China(51725503,51705155);Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-02-E00068)。

摘　　要：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 abovementioned 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.

关 键 词：Cold expansion process Laser texturing process Surface integrity Microstructure evolution 

分 类 号：TG132.3[一般工业技术—材料科学与工程]