Strength of non-smooth unit fabricated by laser and its effect on thermal fatigue behavior of 3Cr2W8V die steel inspired from the biological system

Zhihui Zhang (a), Hong Zhou (a,*), Xin Tong (a), Hongyu Shan (a), Na Sun (a), Luquan Ren (b)

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.