High Strain Rate Properties of Various Forms of Ti6Al4V(ELI) Produced by Direct Metal Laser Sintering

For analysis of engineering structural materials to withstand harsh environmental conditions, accurate knowledge of properties such as flow stress and failure over conditions of high strain rate and temperature plays an essential role. Such properties of additively manufactured Ti6Al4V(ELI) are not adequately studied. This paper documents an investigation of the high strain rate and temperature properties of different forms of heat-treated Ti6Al4V(ELI) samples produced by the direct metal laser sintering (DMLS). The microstructure and texture of the heat-treated samples were analysed using a scanning electron microscope (SEM) equipped with an electron backscatter diffraction detector for electron backscatter diffraction (EBSD) analysis. The split Hopkinson pressure bar (SHPB) equipment was used to carry out tests at strain rates of 750, 1500 and 2450 s(-1), and temperatures of 25, 200 and 500 degrees C. The heat-treated samples of DMLS Ti6Al4V(ELI) alloys tested here were found to be sensitive to strain rate and temperature. At most strain rates and temperatures, the samples with finer microstructure exhibited higher dynamic strength and lower strain, while the dynamic strength and strain were lower and higher, respectively, for samples with coarse microstructure. The cut surfaces of the samples tested were characterised by a network of well-formed adiabatic shear bands (ASBs) with cracks propagating along them. The thickness of these ASBs varied with the strain rate, temperature, and various alloy forms.

Automated summary

This paper investigates the high strain rate and temperature properties of heat-treated Ti6Al4V(ELI) samples produced by direct metal laser sintering (DMLS). The study found that the heat-treated DMLS Ti6Al4V(ELI) alloys were sensitive to strain rate and temperature, with samples of finer microstructure exhibiting higher dynamic strength and lower strain, and samples of coarse microstructure showing lower dynamic strength and higher strain. Additionally, the cut surfaces of the tested samples were characterized by a network of adiabatic shear bands (ASBs) with cracks propagating along them, with the thickness of ASBs varying with strain rate, temperature, and alloy forms.