Thermal fatigue behavior of medium carbon steel with striated non-smooth surface

Abstract

Imitating the body surface morphology of some biological systems, the medium carbon steel specimens with biomimetic surface were manufactured by laser processing technique. The key feature of this biomimetic surface is to arrange a various spacing of striations to create a non-smooth working surface. The thermal fatigue behavior of specimens with different surfaces, i.e. the specimen with 2-mm-spacing striations, 4-mm-spacing striations and smooth surface, was investigated and compared. It was found that the biomimetic surface has a beneficial effect on improving the thermal fatigue behavior of medium carbon steel, and that the specimen with 2-mm-spacing striations had the highest resistance to thermal fatigue. Compared with the base material, the striation zone on the non-smooth surface was mainly characterized by the refinement of grains and the alteration of microstructure. Based on such strengthening mechanism as well as the emergence of huge compressive residual stress in the striation zone, the pile–nail effect, which is proposed initially and can be explained by crack retardation mechanism together with stress counteraction mechanism, is the main reason for enhancing the thermal fatigue resistance of medium carbon steel with biomimetic surface.