Dynamic compressive properties and underlying failure mechanisms of selective laser melted Ti-6Al-4V alloy under high temperature and strain rate conditions

摘要

In this study, high speed impacting tests are systematically conducted on a split Hopkinson pressure bar device to investigate the strain rate and temperature dependence of dynamic compressive properties of Ti-6Al-4 V (TC4) fabricated by selective laser melting (SLM), the ranges of strain rate and temperature are 2000-6000/s and 25-650 celcius, respectively. The results reveal that the yield strength and ultimate compressive strength of the SLMTC4 alloy increase with the increasing strain rate and the decreasing temperature, showing obvious strain rate and temperature sensitivities. The high speed impacting load intensifies the texture of the SLM-TC4 alloy significantly. Adiabatic shear band (ASB) is more likely to evolve at higher temperatures and strain rates, submicron equiaxed grains formed in the ASB and the surrounding area are mainly ascribed to the combination of dynamic recrystallization, deformation-induced twinning and transverse alpha-lath splitting. Within the ASB, grains with {0001} pole orientation are rotated by approximately 45 degrees with respect to the shear direction, indicating that the recrystallized grains are able to reorient themselves to accommodate to the shear deformation. The findings in this work provide a theoretical basis to understand the deformation behavior and mechanism of SLMTC4 alloy under impacting loads, thus is helpful to widen the application of SLM technique and products.

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