Diode laser surface modification of Ti6Al4V alloy to improve erosion wear resistance

Purpose: Purpose of this paper : The purpose of the study was to develop new laser alloying technology providing high erosion wear resistance of the working surfaces of blades made of titanium alloy Ti6Al4V. Design/methodology/approach: High power diode laser HPDL with a rectangular laser beam spot of multimode and uniform intensity of laser radiation was applied in the process of laser surface modification of the titanium alloy Ti6Al4V. During the laser surface remelting and alloying of the titanium alloy in argon and nitrogen atmospheres, surface layers of high hardness and significantly higher erosion wear resistant, compared with the base material of titanium alloy Ti6Al4V, were produced. Findings: The surface layers are composites of titanium nitrides participations in the titanium alloy matrix. Hardness of the surface layers and erosion wear resistance depends strongly on parameters of laser processing and on the partial pressure of nitrogen in the gas mixture of nitrogen-argon atmosphere. Research limitations/implications: The most critical parameter of the functional quality of titanium alloy blades of turbofan engine and steam turbines is the fatigue strength, therefore further investigations are required to determine the fatigue strength and also internal stresses in the nitrided surface layers. Practical implications: The novel technology of high power diode laser surface modification of the titanium alloy Ti6Al4V can be applied to produce erosion wear resistant and long lifetime surface layers of turbofan engine blades and steam turbine blades. Originality/value: The laser surface modification of titanium alloy by the high power diode laser with the rectangular laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case of laser surface remelting and alloying because the treated surface is heated uniformly, so uniform penetration depth and uniform thickness of the surface layer can be achieved, as opposed from circular laser beams of solid states YAG and gas lasers.