Defect-healing of a laser-powder bed fusion Ti6Al4V alloy via electro-assisted micro-forging

• Published in: Materials characterization 2023-11, Vol.205, p.113298, Article 113298
• Main Authors: Meng, L.X., Yang, H.J., Wang, S.G., Ji, H.B., Shao, X.H., Zhang, Z.J., Ren, D.C., Zhang, X., Yang, J.B., An, X.H., Pei, Y.T., De Hosson, J.Th.M., Yang, R., Zhang, Z.F.
• Format: Article
• Language: English
• Subjects: Defect-healing; Electro-assisted micro-forging; Laser-powder bed fusion; Mechanical properties; Ti6Al4V
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2023.113298

In recent years, the concept of hybrid manufacturing has been proposed to heal the defects in additive manufactured (AM) materials, taking advantage of both the AM technique and additional secondary processes such as hot forging. However, the healing mechanism of defects, as well as the relationship between defects elimination and microstructure evolution need to be further studied. In this work, we designed laser-powder bed fusion (L-PBF) Ti6Al4V samples with high initial porosity, making it easier to trace the pores during the quasi in-situ X-ray tomography (XRT) observation. The samples were conducted hot forging by Gleeble-3800 system, which is named as electro-assisted micro-forging (EAMF) treatment, considering the characteristic of this process is to directly electrify the specimen to generate Joule heat. The results show that the porosity was effectively reduced by combining effects of electric current, heat energy and compressive stress during EAMF. Simultaneous enhancement of strength and ductility was realized. The defect-healing mechanism that comprising various stages was comprehensively disclosed. The competitive relationship between defect-healing and microstructure coarsening was revealed, which has a guiding effect on the subsequent optimization of process parameters. [Display omitted] •An electro-assisted micro-forging (EAMF) treatment induces significant defect-healing effect.•Simultaneous enhancement of strength and ductility was achieved.•The defect-healing mechanism comprising three stages was disclosed.•A competitive relationship between defect-healing and microstructure coarsening was revealed.•Interrupted In-situ XRT and FIB-TEM were used.