The thermal fatigue resistance of vermicular cast iron coupling with H13 steel units by cast-in process

This paper focuses on improving the thermal fatigue resistance on the surface of vermicular cast iron coupling with inserted H13 steel blocks that had different cross sections, by cast-in processing. The microstructure of bionic units was examined by scanning electron microscope. Micro-hardness and thermal fatigue resistance of bionic samples with varied cross sections and spacings were investigated, respectively. Results show that a marked metallurgical bonding zone was produced at interface between the inserted H13 steel block and the parent material – a unique feature of the bionic structure in the vermicular cast iron samples. The micro-hardness of the bionic samples has been significantly improved. Thermal resistance of the samples with the circular cross section was the highest and the bionics sample with spacing of 2 mm spacing had a much longer thermal fatigue life, thus resulting in the improvement for the thermal fatigue life of the bionic samples, due to the efficient preclusion for the generation and propagation of crack at the interface of H13 block and the matrix.