Study on preheating and annealing treatments to biomimetic non-smooth cast iron sample with high thermal fatigue resistance

According to the previous studies, biomimetic non-smooth samples fabricated by laser melting had superior resistance to thermal fatigue compared with smooth sample. In order to improve the treating technology for biomimetic non-smooth surface of cast iron samples so as to enhance their thermal fatigue resistance further, preheating and annealing were applied in the procedure. Moreover, the effects of preheating and annealing treatments on the microstructure and microhardness of the biomimetic non-smooth units were also investigated. The results indicated that the cracks and holes in non-smooth units caused by laser processing could be avoided by preheating at an appropriate temperature, and the residual stresses in non-smooth units were eliminated largely through annealing. Of all samples tested, those preheated at 250 °C during laser processing and then annealed had the best thermal fatigue resistance.