Multiple α sub-variants and anisotropic mechanical properties of an additively-manufactured Ti-6Al-4V alloy

• 作者: Yinling Zhang Zhuo Chen Shoujiang Qu Aihan Feng Guangbao Mi Jun Shen Xu Huang Daolun Chen
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（11）
• 页码范围: 113-124
• 页数: 12页
• 语种: 英文

摘要

Additive manufacturing(AM)is a promising material processing method which gains significant momen-tum 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 crys-tallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundant α lamellae with six variants were present inside the columnar prior-β grains with a<100>fiber texture during β→α phase transformation.The six αvariants followed the Burgers orientation relationship of{110}β//{0001}α and<1-11>β//<11-20>α.Mul-tiple sub-variants in each α variant were observed for the first time.The anisotropy in the mechanical properties was mainly related to the relative amount of six α variants.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 stabiliza-tion 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.