Research On Surface Quality Of Laser Repair And Milling Process For Titanium Alloy Parts

Titanium alloy(TC4)is the main material for manufacturing compressor blades and fan blades of aero-engine.Foreign objects carried by high-speed airflow are easy to cause damage to the blades,which need to be replaced or repaired before the damaged blades can continue to serve.Replacement of new blades will greatly increase the operating cost and it is more economical to repair and remanufacture the damaged blades.At present,as an advanced manufacturing technology,laser cladding is widely used in aviation maintenance,but the surface quality of the repaired cladding layer can not directly meet the requirements.Therefore,it is of great significance to study the effect of changes in laser repair and milling process parameters on the surface quality of titanium alloy parts.The material of aero-engine blades TC4 Titanium alloy was taken as the substrate material as well as TC4 and WC powder were taken as the raw material.Multi-channel single-layer TC4 cladding layers and TC4/WC composite cladding layers(WC content from 10% to 30%)with different scanning speeds(from 6mm/s to18mm/s)were prepared on titanium alloy substrate by laser cladding.The microstructure and phase of TC4 cladding layers and TC4/WC composite cladding layers were analyzed by scanning electron microscopy and XRD diffractometer.The hardness and wear resistance of TC4 cladding layer and TC4/WC composite cladding layers were tested by the Vickers hardness tester and friction and wear tester.The results show that the microstructure of TC4 cladding layer is mainly basket structure and the phase composition is mainly α-Ti.Compared with the substrate,the hardness of TC4 cladding layer is improved,but the wear resistance is improved little or even decreased slightly;The microstructure of TC4/ WC composite cladding layer mainly presents dendrite,columnar and granular,and new phases such as W2 C,Ti C,W and C are formed.Compared with the substrate and TC4 cladding layer,the hardness is improved,and the wear resistance is greatly improved.The TC4 cladding layer and TC4 / WC composite cladding layer were milled by changing the cutting speed(94.2m/min ~ 282.6m/min)of five axis CNC machining center.The influence of cutting speed on milling force and surface quality of TC4 cladding layer and TC4 / WC composite cladding layer was studied.The milling force and surface roughness were measured by dynamometer and white light interferometer.The influence of cutting speed on the milling force,line profile and surface roughness of TC4 cladding layer and TC4 / WC composite cladding layer was obtained,which provided theoretical and experimental support for the research on surface quality of laser repair milling of titanium alloy parts.