Crack behavior in ultrafast laser drilling of thermal barrier coated nickel superalloy

•A thermo-mechanical coupled model is established to obtain temperature, phase transformation stress and thermal stress.•The nonlinear relationship between drilling depth and drilling time is considered.•The behaviors of the interfacial crack and the internal crack are quantitatively analyzed.•The drilling strategy is suggested to reduce the thermal effect. Quantitative analysis is required to explore the mechanism of crack generation in ultrafast laser drilling of thermal barrier coated nickel superalloy. In this study, a simple thermo-mechanical coupled model is established to obtain temperature history, phase transformation stress and thermal stress during drilling process, in which laser beam scanning, laser intensity attenuation, the nonlinear relationship between drilling depth and drilling time are involved. The induced stress obtained from the present model is compared with the results by digital image correlation (DIC) method. According to the crack distribution around the drilled hole, the present model is used to explain the mechanism of crack behavior in drilling of multilayer materials. Finally, the strategy using low pulse repetition rate or water jet assisted method is suggested to reduce the thermal effect in ultrafast laser drilling process.