Enhanced Microstructure and Wear Resistance of Ti-6Al-4V Alloy with Vanadium Carbide Coating via Directed Energy Deposition.

Ti-6Al-4V alloys are known for their suboptimal tribological properties and are often challenged by durability issues under severe wear conditions. This study was conducted to enhance the alloy's wear resistance by forming a hardened surface layer. Utilizing directed energy deposition (DED) additive manufacturing with a diode laser, vanadium carbide particles were successfully integrated onto a Ti-6Al-4V substrate. This approach deviates from traditional surface enhancement techniques like surface hardening and cladding, as it employs DED additive manufacturing under parameters akin to those used in standard Ti-6Al-4V production. The formed vanadium carbide layer achieved a remarkable thickness of over 400 µm and a Vickers hardness surpassing 1500 HV. Pin-on-disk test results further corroborated the enhanced surface wear properties of the Ti-6Al-4V alloy following the additive-manufacturing process. These findings suggest that employing vanadium carbide additive manufacturing, under conditions similar to the conventional DED process with a diode laser, significantly improves the surface wear properties of Ti-6Al-4V in metal 3D-printing applications.

Interlayer Tailoring of Ti-6Al-4V and 17-4PH Stainless Steel Joint by Tungsten Inert Gas Welding.

The development of robust and efficient methods for constructing and joining complex metal specimens with high bonding quality and durability is of paramount importance for various industries, e.g., aerospace, deep space, and automobiles. This study investigated the fabrication and characterization of two types of multilayered specimens prepared by tungsten inert gas (TIG) welding: Ti-6Al-4V/V/Cu/Monel400/17-4PH (Specimen 1) and Ti-6Al-4V/Nb/Ni-Ti/Ni-Cr/17-4PH (Specimen 2). The specimens were fabricated by depositing individual layers of each material onto a Ti-6Al-4V base plate, and subsequently welding them to the 17-4PH steel. The specimens exhibited an effective internal bonding without any cracks, accompanied by a high tensile strength, with Specimen 1 exhibiting a significantly higher tensile strength than Specimen 2. However, the substantial interlayer penetration of Fe and Ni in the Cu and Monel layers of Specimen 1 and the diffusion of Ti along the Nb and Ni-Ti layers in Specimen 2 resulted in a nonuniform elemental distribution, raising concerns about the lamination quality. This study successfully achieved elemental separation of Fe/Ti and V/Fe, which is vital for preventing the formation of detrimental intermetallic compounds, particularly in the fabrication of complex multilayered specimens, representing the prime novelty of this work. Our study highlights the potential of TIG welding for the fabrication of complex specimens with high bonding quality and durability.