The comparative study of thermal fatigue behavior of H13 die steel with biomimetic non-smooth surface processed by laser surface melting and laser cladding

According to previous studies, the thermal fatigue behavior of hot-work tool steel with biomimetic non-smooth surface treated by laser surface melting (LSM) gets a significant improvement. However, the properties of LSM non-smooth unit degenerate during thermal cycles. In order to improve the properties of non-smooth unit during thermal cycles, laser cladding (LC) was employed to fabricate the non-smooth unit. Before and after thermal fatigue testing, the microstructure and microhardness of non-smooth unit treated by LSM and LC have been investigated. The results showed that the non-smooth sample processed by LC is more effective to improve thermal fatigue behavior than that treated by LSM. During the thermal fatigue testing, LC non-smooth unit had better resistance to thermal cycles softening compared with LSM non-smooth unit. After thermal fatigue testing, a distinct change of the microstructure of LSM non-smooth unit was detected, i.e., the grains of the non-smooth unit became coarsening obviously. However, the microstructure of LC non-smooth unit was not changed significantly after thermal fatigue testing.