Effect of annealing process on microstructure and room temperature mechanical properties of selective laser melted Ti6Al4V alloy

doi:10.13251/j.issn.0254-6051.2020.08.021

Abstract

Abstract: Ti6Al4V alloy specimens were prepared from Ti6Al4V spherical powder by laser selective melting (SLM) process, and effect of annealing process on the room temperature mechanical properties and microstructure of the SLM Ti6Al4V alloy were studied by means of optical microscope, scanning microscope and tensile test. The results show that the room temperature tensile strength of the alloy without heat treatment exceeds 1200 MPa, but the average fracture elongation is only 4.0%. Under the condition of vacuum annealing at 650 ℃, the tensile strength of the alloy is still around 1200 MPa, and the R_p0.2 is higher than 1150 MPa, but the percentage elongation after fracture is below 10%, the overall stvength and toughness of the material has been significemtly improved. The tensile strength of the alloy is decreased to 1100 MPa when vacuum annealed at 750 ℃ and 800 ℃, the R_p0.2(the proof strength, plastic extension) is higher than 1050 MPa and the percentage elongation after fracture is greater than 10%. Furthermore, with the increase of heating temperature and holding time of vacuum annealing, the original β grain boundary of the alloy formed by laser selective melting becomes blurred gradually and the grains tend to be equiaxed. In the meantime, the needle-like α′ martensite formed with rapid cooling transformation does not appear obviously coarsening.

Key words: Ti6Al4V alloy, selective laser melting, annealing process, mechanical properties, microstructure

CLC Number:

TG146.2

Xiao Meili, Zan Lin, Ke Linda, Deng Zhujun, Lai Caifang, Sun Jingli. Effect of annealing process on microstructure and room temperature mechanical properties of selective laser melted Ti6Al4V alloy[J]. Heat Treatment of Metals, 2020, 45(8): 108-112.

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