Nodular iron brake discs typically fail due to serious thermal fatigue cracking, and the presence of graphite complicates the repair of crack defects in ductile iron. This study presents a novel method for remanufacturing ductile iron brake discs based on coupled bionics to repair thermal fatigue cracks discontinuously using bio-inspired crack blocking units fabricated by laser remelting at various laser energy inputs. Then, the ultimate tensile force and thermal fatigue crack resistance of the obtained units were tested. The microhardness, microstructure, and phases of the units were characterized using a digital microhardness meter, optical microscopy, scanning electron microscopy, and X-ray diffraction. It was found that the units without defects positively impacted both the thermal fatigue resistance and tensile strength. The unit fabricated at a laser energy of 165.6 − 15 + 19 J/ mm 2 had sufficient depth to fully close the crack, and exhibited superior anti-cracking and tensile properties. When the unit distance is 3 mm, the sample has excellent thermal fatigue resistance. In addition, the anti-crack mechanism of the units was analysed.

To study the effect of laser biomimetic treatment on different material compositions, five kinds of steels with different carbon element contents were studied by laser remelting. The characteristics (depth, width), microstructure, hardness, tensile properties, and wear resistance of the samples were compared. The results show that when the laser processing parameters are fixed, the characteristics of the unit increase with an increase of carbon element content. Moreover, the hardness of the unit also increases. Compared with the untreated samples, when the carbon content is 0.15–0.45%, the tensile strength of the laser biomimetic samples is higher than that of the untreated samples. For the biomimetic samples with different carbon content, with an increase of carbon content, the tensile strength increases first and then decreases, while the plasticity of the biomimetic samples decreases continuously. The bionic samples have better wear resistance than that of the untreated samples. For bionic specimens with different carbon elements, wear resistance increases with an increase of carbon element content.

It is important to solve the partial fatigue wear of large forging dies, where the service life can be short. The purpose of this paper is to use laser remelting biomimetic technology to prepare a coupling biomimetic model combination on the mold surface, strengthen the local fatigue wear resistance of the mold, and extend the service life of the mold. Three types of laser energies were used to prepare the coupling biomimetic elements and analyze the microstructure and phase composition of the specific gravity melting zone. The biomimetic units were combined into a variety of coupling biomimetic models (fringe, mesh, and dense array models with different laser energies), and the number of fatigue cracks and the weight of wear loss of the coupling biomimetic model were compared at different temperatures. The mechanism of the coupling bionic model was analyzed, and the coupling bionic surface with a dense row structure was determined to have strong anti-fatigue wear performance. According to the Range Method, the relationship between wear and fatigue temperature and laser energy of the coupled bionic model was determined. Using DEFORM software to simulate the stress, temperature, and wear conditions of the front axle die surface, different coupling biomimetic model combinations were prepared on the abrasive surface. The die wear and cut edge width of the forgings were reduced after practical production, which proved that the laser bionic local strengthening method can effectively prolong the service life of a die.

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