Laser surface modification of titanium alloys

Melting of multipass surface tracks in steel incorporating titanium carbide powders

“…The highest hardness recorded in the overlapping tracks is lower than the maximum hardness of 900-1200 HV reported previously in TiC incorporated composite coatings in steel, processed by single track melting. 8,18 This decrease in hardness is related both to the high energy input used in this work and to the effect of preheat generated by the overlapping process, decreasing the cooling rate and modifying the microstructure.…”

“…High energy laser and electron beam melting techniques are established means of processing such composite layers, which are reported to increase wear and corrosion resistance significantly. [1][2][3][4][5][6][7][8] However, application of these techniques is limited in practice because of the high costs of the equipment. Previous surface engineering work using the tungsten inert gas (TIG) welding torch melting technique, [9][10][11][12][13][14][15][16][17][18][19] produced either a small hemispherical volume of a modified surface, or a single melt track with a width of a few millimetres running the length of the specimen.…”

Laser Surface Modification — A Focus on the Wear Degradation of Titanium Alloy

“…Laser surface melting is a process where a thin layer of the substrate is melted by a high-power laser beam, which is then rapidly solidified without any attempt to modify the surface layer chemical composition [6]. The main advantage of this process over other laser modification processes is its ability to alter the microstructure without changing the composition [11].…”

“…Here, the powder and thin layer of the substrate rapidly reach their melting point causing homogenization to be achieved before solidification due to the photon energy absorption [33]. With this, vaporization is avoided due to rapid heating and solidification of the molten clad, which helps to inhibit long-range diffusion, avoid crystallization, achieve strong metallurgical bond with the substrate, and increase hardness [6,34]. Laser beam-specific thermal characteristics induced by laser irradiation help generate specific microstructures, including metastable phases and nano-crystalline grains, which is an advantage over conventional techniques [35].…”

“…For example, higher operating temperatures of cars and turbine engines allow more efficient energy (fuel) conversion with lower toxic emissions [5]. In addition, titanium also has a high melting point, 1678 °C, indicating that it shows good creep resistance over different range of temperatures [6,7]. However, with the distinctive advantages, voiding catastrophic breakdown in application of titanium in higher service temperature and friction in aerospace and automobile industries justifies the need for surface engineering techniques for improving performance of engineering components, longer component life, and failure prevention.…”