INFLUENCE OF PROCESS PARAMETERS AND ENERGY DENSITY ON THE MICROSTRUCTURE OF TI-6AL-4V WIRE/WC POWDER CLADDING

摘要

Laser cladding offers an excellent means for surface coating and alloying. Areas of a component can be targeted and locally modified with the properties tailored to meet specific applications. Research has generally concentrated on the use of powder. Here, work on a laser process of coincidentally fed wire and powder is presented, where the microstructure is altered depending on the laser parameters used, giving the ability to deposit functionally graded materials. Optical, SEM, EDS, XRD and microhardness have been used to characterise the clad layers. Results for the deposition of Ti-6Al-4V wire with WC powder using a 2 kW IPG fibre laser show that the amount of dissolution and distribution of the WC powder can be controlled, being largely influenced by the laser power, interaction time and energy density used. At a given energy density (257 J/mm~2) no WC particles were observed in clads at higher powers (1.8 kW), whereas at lower power (1.2 kW) but the same energy density (257 J/mm~2) WC particles were still present within the clad with interaction times 1.1 second and 1.6 second respectively. Similarly, the formation and morphology of the TiC formed within the clad layer can be tailored to specific requirements.