A simulation and experiment study on phase transformations of Ti-6Al-4V in wire laser additive manufacturing

Materials & Design

Tao Jing¹  Nanfu Zong²  Weizhao Sun²  Hongbiao Dong³  Feihu Shan⁴ 

[1] Corresponding authors.;Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China;School of Engineering, University of Leicester, LE1 7RH, UK;Science and Technology on Power Beam Processes Laboratory, Beijing Key Laboratory of High Power Beam Additive Manufacturing Technology and Equipment, Aeronautical Key Laboratory for Additive Manufacturing Technologies, AVIC Manufacturing Technology Institute, 100024 Beijing, China;

关键词: Additive manufacturing;    Ti-6Al-4V;    Simulation;    Phase transformation;   

DOI  :  

来源: DOAJ

【 摘 要 】

The additively manufactured Ti-6Al-4V part suffers from undesirable α′ phase, which leads to a decrease of its plasticity. In this research, density-based constituent phase simulation method is applied to investigate the phase transformation of Ti-6Al-4V during wire laser additive manufacturing (WLAM). Single-layer and five-layer WLAM experiments are conducted to validate the accuracy of the simulation. The simulation results agree with the experimental results. By in-situ investigating the phase transformation during cooling, it is found that there exist four stages for β→α/α′, which are (I) β→αgb/αC, (II) β→αB, (III) β→α′ and (IV) β→αB and α′→αB+β. Increasing the temperature and decreasing the cooling rate help in narrowing or even eliminating the β→α′ stage, which finally leads to the decrease of α′ fraction or even avoid its formation. Compared with the laser power 2500 W case, the laser power 3000 W case gets more transformed αB without increasing α-lath thickness. The simulation shows promising prospects in predicting phase transformation, revealing underlying mechanisms and optimizing processing parameters.

【 授权许可】

Unknown