Experimental investigation of laser peening on TiAl alloy microstructure and properties

 In order to study the effect of laser peening on microstructures and properties of TiAl alloy, TiAl alloy samples were treated by Nd:YAG laser system with the wavelength of 1064 nm, pulse-width of 18 ns, and pulse-energy of 0-10 J. Surface micro-hardness, roughness, and microstructural characteristics were tested with micro-hardness tester, roughness tester and scanning electron microscope. Residual stress and pole figures were tested with X-ray diffraction and its high-temperature stability was analyzed. The experimental results show that surface micro-hardness increases by up to 30%, roughness increases to 0.37 μm, compressive residual stress increases to 337 MPa, and local texture and typical lamellar microstructure are generated. Residual stress, micro-hardness, and (002) pole figures tests are conducted, compressive residual stress value drops from 337 MPa to 260 MPa, hardness value drops from 377 HV_0.2 to 343 HV_0.2, and the (002) poles shift back to the center slightly. Laser peening improves microstructure and properties of TiAl alloy significantly.