Investigation of nanomechanical properties and thermal fatigue resistance of gray cast iron processed by laser alloying

The effect of laser alloying on thermal fatigue resistance of gray cast iron was investigated and explicated by nanoindentation test. It was founded that nanohardness of alloying zone was improved pronouncedly by generating a homogeneous microstructure which has upgraded chemical composition and refined grains. The load-displacement curves showed that the resistance to plastic flow of alloying zone was better than that of matrix. The alloying zone rich in Cr and Ni has a promoted capability of inhibiting the initiation and blocking the propagation of thermal cracks. It was demonstrated that the resistances of plastic deformation and oxidation reaction in alloying zones were main reasons for their effect of inhibiting cracking. The alloying zone can also be accepted as enlarged hard “phase” because of their high nanohardness, which contributed to the effect of blocking cracks.