Effect of units in different sizes on thermal fatigue behavior of 3Cr2W8V die steel with biomimetic non-smooth surface

Aiming to deeply research the thermal fatigue behavior of 3Cr2W8V die steel with biomimetic surface, the specimens with different sizes of concave-shape and striation-shape units were processed by laser technique. By establishing cross-section model of the units and by calculating their volume, the size of the units was quantitatively expressed, and its effect on thermal fatigue behavior of 3Cr2W8V die steel was investigated and compared. The results showed that the units in different sizes have different degrees of effects on resisting the thermal fatigue cracks; especially those in the larger size can play a greater role in preventing the crack initiation and blocking the crack propagation; and further the influence of the size of the units on thermal fatigue behavior is more sensitive to resist the crack propagation.Based on the self-strengthening of the units, the increased resistance of the units in the larger size to crack initiation can be attributed to the crack prevention mechanism owing to the reduced probability of crack nucleation and the enhanced resistance to plastic deformation on the biomimetic surface, while the enhanced resistance to crack propagation is due to the crack blocking mechanism that results in the slow crack growth rate.