首页|Simultaneous improvement of strength and elongation of laser melting deposited Ti-6Al-4V titanium alloy through three-stage heat treatment
Simultaneous improvement of strength and elongation of laser melting deposited Ti-6Al-4V titanium alloy through three-stage heat treatment
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NSTL
Elsevier
This study reported a strategy of three-stage heat treatment to simultaneously improve yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of laser melting deposited (LMDed) Ti-6Al-4V titanium alloy. After the three-stage heat treatment, the basketweave microstructure consisting of acicular alpha laths in the as-built sample was transformed to a multiscale-alpha microstructure consisting of the coarse-plate alpha, fine-plate alpha and ultrafine alpha in the heat-treated sample. The effect of microstructure on the tensile properties was revealed via in-situ tensile test combined with the analysis of the deformation and fracture mechanism. Although the coarse-plate alpha in heat-treated sample is larger than the acicular alpha in as-built sample, the combination of multiscale alpha grains with a certain relative content aroused an increment of the YS from 879 +/- 28 MPa in as-built sample to 973 +/- 9 MPa in heat-treated sample. The good deformation compatibility among the multiscale alpha grains impeded the crack propagation effectively, which resulted in the improvement of the EL from 14 +/- 2% to 16 +/- 1%. Furthermore, the improvement of the EL enhanced the dislocation multiplication and strain hardening in the multiscale alpha microstructure to induce the increment of the UTS from 945 +/- 40 MPa to 1092 +/- 20 MPa. The results could provide a guidance for tailoring microstructure and improving the strength and ductility of additive manufacturing titanium alloy.
NSTL
Elsevier
