Ductility improvement due to martensite alpha ' decomposition in porous Ti-6Al-4V parts produced by selective laser melting for orthopedic implants

作者：Sallica Leva E; Caram R; Jardini A L; Fogagnolo J B^*

来源：Journal of the Mechanical Behavior of Biomedical Materials, 2016, 54: 149-158.

DOI：10.1016/j.jmbbm.2015.09.020

• Titanium alloys
• Additive manufacturing
• Thermal treatment
• Thermal analysis
• X-ray analysis
• Mechanical properties

Ti-6Al-4V parts obtained by selective laser melting typically have an acicular alpha' martensitic microstructure whose ductility is low. Thus, post-heat treatments are useful for increasing ductility. In this work, the effects of sub-beta-transus heat treatments on the mechanical properties of Ti-6Al-4V parts with porous structures are correlated with martensite alpha' phase decomposition. The precipitation of beta phase and the gradual transformation of alpha' into alpha phase by the diffusion of excess vanadium from alpha' to beta phase are proposed to be the main events of martensite alpha' phase decomposition in parts fabricated by selective laser melting. The heat treatment performed at 650 degrees C for 1 h produced no microstructural changes, but the samples treated for at the same temperature 2 h showed alpha fine precipitation of beta phase along the alpha' needle boundaries. The heat treatment performed at 800 degrees C for 1 or 2 h produced alpha fine alpha+beta microstructure, in which beta phase are present as particles fewer in number and larger in size, when compared with the ones present in the sample heat-treated at 650 degrees C for 2 h. Heat-treatment of the parts at 800 degrees C for 2 h proved to be the best condition, which improved the ductility of the samples while only slightly reducing their strength.

• 出版日期2016-2