Microstructure and properties enhancement of Ti-6Al-4V/TiC cermet cladding layers prepared by laser additive manufacturing

Abstract

Ti-6Al-4V alloy is widely used in aerospace and chemical equipment manufacturing due to its good strength, plasticity, toughness, corrosion resistance and weldability, but its hardness and abrasion resistance are not high enough to limit its service life under frictional wear conditions to some extent. Ti-6Al-4V alloy homogeneous cermet cladding layer with TiC-added phase was additively prepared based on the optimized process method of laser cladding, and the strengthening effect of TiC enhancement with respect to the cladding layer microstructure as well as the basic mechanical properties was characterized and verified. The results show that the main phases of the cladding layer include α-Ti, β-Ti and TiC, of which TiC is supersaturated and precipitated within the cladding layer. Due to the difference in the supercooling degree at different locations of the cladding layer, the precipitated TiC is mainly in the form of fine particles at the top of the cladding layer, while it is mainly in the form of dendrites and petals in the middle of the cladding layer. The bottom of the cladding has a new wheat spikes precipitation shape, while no significant TiC precipitation is seen in the dilution zone. The average microhardness of the cladding layer is 530HV0.5, which is 61% higher than that of the substrate; the average friction coefficient of the cladding layer is 0.3583 at 35 N load, which is 11% lower than that of the substrate, and the volume wear rate is about 87% that of the substrate, and the wear is in the form of adhesive wear and abrasive wear.

Keywords

• laser cladding
• ti-6al-4v
• tic
• cladding layer
• microstructure and property