Enhancing mechanical strength of Ti-6Al-4V sheet material by short-time sub-β-transus solution heat treatment and additional short-time annealing

ductility can be obtained by solution heat treatment just below the β-transus temperature followed by quenching.In literature it is indicated that additional short-time annealing can significantly enhance the material’s strength.Based on these studies, this work aims to understand the influence of short-time solution heat treatment parametersand additional short-time annealing on the mechanical properties of Ti-6Al-4V sheet material, with agoal of evaluating the suitability of short-time heat treatments for implementation in processing techniques forsheet metal parts. A vertical furnace purged with Argon gas was employed to produce various materials states viashort-time solution heat treatment and water quenching and additional short-time annealing. The solution heattreatment parameters were systematically varied as follows: (i) solution heat treatment temperature in the rangeof 875 ◦C–955 ◦C and (ii) solution heat treatment time in the range of 70 s–540 s. The effects of (i) and (ii) wereinvestigated both without and with an additional short-time annealing at 570 ◦C for 180 s. Microstructuralproperties investigated by scanning electron microscopy combined with mechanical properties obtained bytensile and nanoindentation tests allow comprehensive evaluation of the different material conditions. It wasobserved that the application of an additional short-time annealing to the solution heat treated and quenchedmaterial resulted in a pronounced increase in strength, which was attributed to the hardening of the martensiticallytransformed prior β-grains, while maintaining moderate ductility. The solution heat treatment temperatureis the crucial parameter influencing microstructure (e.g. phase fractions, interface characteristics, chemicalphase composition) and, consequently, the deformation behavior within the solution heat treatment step.Increasing the solution heat treatment temperature resulted in higher strength and reduced ductility, allowingthe mechanical properties to be tailored for specific future technological applications. In contrast, the solutionheat treatment time in the range investigated did not have a substantial impact on mechanical properties.