Microstructure features induced by fatigue crack initiation up to very-high-cycle regime for an additively manufactured aluminium alloy  

作　　者：Xiangnan Pan Leiming Du Guian Qian Youshi Hong 

机构地区：[1]State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Journal of Materials Science & Technology》2024年第6期247-260,共14页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(No.11932020).

摘　　要：Fatigue failure can still occur beyond 107 cycles,i.e.very-high-cycle fatigue(VHCF),in many metallic materials,such as aluminium alloys and high-strength steels.For VHCF of high-strength steels,a fine granular area(FGA)surrounding an inclusion is commonly identified as the characteristic region of crack initiation on the fracture surface.However,no such FGA feature and related crack initiation behaviour were observed in VHCF of conventionally cast or wrought aluminium alloys.Here,we first reported the distinct mechanisms of crack initiation and early growth,namely the microstructure feature and the role of FGA in VHCF performance for an additively manufactured(AM)AlSi10Mg alloy.The AM pores play a key role in fatigue crack initiation similar to that of the inclusions in high-strength steels,resulting in almost identical FGA behaviour for different materials under a range of mean stress with a stress ratio at R<0 or R>0.The profile microstructure of FGA is identified as a nanograin layer with Si rearrangement and grain boundary transition.This process consumes a large amount of cyclic plastic energy making FGA undertake a vast majority of VHCF life.These results will deepen the understanding of VHCF nature and shed light on crack initiation mechanism of other aluminium and AM alloys.

关 键 词：Aluminium alloy Additive manufacturing NANOGRAINS Very-high-cycle fatigue(VHCF) Crack initiation Mean stress 

分 类 号：V261[航空宇航科学与技术—航空宇航制造工程] V46