Abstract
Additive manufacturing (AM) has emerged as a promising technique for producing high-performance titanium alloys, particularly, Ti–6Al–4V, due to its design flexibility, near-net-shape fabrication, and efficient material use. This study presents a comprehensive analysis of the microstructural features and mechanical properties of Ti–6Al–4V alloys fabricated by various AM methods, with a primary focus on selective laser melting (SLM), direct metal laser sintering (DMLS), and wire arc additive manufacturing (WAAM). The influence of processing parameters (such as laser power, scanning speed, hatch spacing, and energy density) on porosity, grain morphology, and anisotropy is critically examined based on recent experimental findings. The role of heat treatment in modifying microstructure, relieving residual stresses, and improving strength and ductility is also discussed. The article provides a detailed review of recent experimental and analytical studies on the influence of AM parameters, particularly, WAAM, on the formation of microstructure and mechanical performance of Ti–6Al–4V. Emphasis is placed on the effects of wire feed rate, arc current, interlayer cooling temperature, and thermal cycling on structural heterogeneity, grain size, α/β-phase distribution, and melt zone defect formation. The role of thermal and thermomechanical post-processings in reducing residual stresses and enhancing plasticity and structural homogeneity is analysed. The review also considers morphological transitions between columnar and equiaxed grains, phase transformations across various deposition zones, and the effects of cooling rate on crystallographic texture. Comparative evaluation reveals that powder bed fusion technologies enable superior resolution and mechanical performance, while WAAM is better suited for large-scale components, but requires additional post-processing to reduce thermal gradients and texture-induced anisotropy. Representative case studies highlight correlations between process conditions and tensile strength, elongation, hardness, and fracture behaviour. Constructive process design strategies for thermal-field control and deformation minimisation during deposition are outlined. The findings underline the importance of integrated parameter optimisation and post-treatment strategies to meet aerospace standards such as AMS 6932. The article is relevant for specialists in physical metallurgy, materials science, and aerospace engineering, as it contributes to a scientifically grounded understanding of the relationship between WAAM-process parameters and the microstructural and mechanical characteristics of additively manufactured titanium alloys.