摘要
Additive manu facturing(AM)is a promising material processing method which gains significant momentum in the aerospace and biomedical industries.However,the anisotropy in the mechanical properties of additively-manufactured materials is still poorly understood.This study was aimed at elucidating crystallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundantαlamellae with six variants were present inside the columnar prior-βgrains with a<100>fiber texture duringβ→αphase transformation.The sixαvariants followed the Burgers orientation relationship of{110}_(β)//{0001}_(α)and<1-11>_(β)//<11-20>_(α).Multiple sub-variants in eachαvariant were observed for the first time.The anisotropy in the mechanical properties was mainly related to the relative amount of sixαvariants.While the horizontally-oriented samples had a lower yield strength,they exhibited a higher ductility and longer fatigue life than the vertically-oriented samples.Cyclic softening occurred at higher strain amplitudes,and cyclic stabilization sustained at lower strain amplitudes.Fatigue crack mainly initiated from the specimen surface at lower strain amplitudes,while multiple crack initiation tended to occur at higher strain amplitudes.Crack propagation was characterized by fatigue striations along with some secondary cracks.
基金
financial support provided by the National Natural Science Foundation of China(NSFC)(Grant No.51871168)
the Natural Sciences and Engineering Research Council of Canada(NSERC)in the form of international research collaboration
China Scholarship Council(CSC)for providing a PhD scholarship。
