Jilin University, China
Inspired by the body surface of biological system, the specimens with non-smooth units of different strength were obtained by laser processing with varying parameters. The effect of strength of non-smooth unit on thermal fatigue behavior of 3Cr2W8V steel was investigated, and thermal fatigue behavior of specimens with smooth and non-smooth surface was compared. Before and after thermal fatigue test, microhardness, microstructure and dislocation density within the unit zone were measured and analyzed. It was found that the initiation of thermal cracks always occurs in the matrix; non-smooth surface remarkably improves the thermal fatigue resistance compared to the smooth surface. The non-smooth unit plays a decisive role in preventing the crack initiation and stopping the crack propagation especially those with higher strength, due to its higher strength and thermal stability, dense dislocations and refined microstructure. Relevant mechanisms behind these results are discussed.