The stress state is important for properties and service life of mechanical parts, so finding an optimal method for evaluation of stress state is urgently needed to be solved. Because of convenience and fast detection speed, metal magnetic memory method has attracted attention of scholars, and some research findings also have been obtained. While current research mainly focuses on evaluation of stress state of single ferromagnetic material, the research on ferromagnetic composite material or ferromagnetic coating material is rare. Because of high energy density, laser cladding technology has been used widely in field of surface engineering. For this reason, the stress state of ferromagnetic laser cladding Fe314 alloy coating is evaluated with metal magnetic memory method. Distribution of stress state is usually affected by flaw including crack and gas hole in laser cladding Fe314 alloy coating, so the interaction influence of crack and load on evaluation of stress state of laser cladding Fe314 alloy coating is discussed in this work. Combing with equivalent method, different cracks, which were substituted with regular rectangular grooves, were machined in laser cladding Fe314 alloy coating. In order to obtain the relationship between burial depth and magnetic field intensity normal component H-p(y), the regular rectangular grooves that had the same width and different buried depths were machined. The microstructure of laser cladding coating was observed by SEM, and the influence of microstructure on magnetic field intensity normal component Hp(y) was also discussed. Based on magnetic- mechanical theory, interaction influence mechanism of crack and load on evaluation stress state of laser cladding coating with metal magnetic memory method was clarified, the relationship between burial depth of crack, load and gradient value K of magnetic field intensity normal component H-p(y) was also obtained. The results show that when zero crossing is seen as center, the magnetic field intensity normal component Hp(y) rotates clockwise as stress increases gradually, the slope and amplitude of Hp(y) curve increases, gradient value K of magnetic field intensity normal component Hp(y) corresponding to crack also increases as stress increases. Stress concentration in different zones is caused by anisotropic microstructure and layer interface of laser cladding Fe314 alloy coating, so the Hp(y) fluctuats obviously. When load is the same, gradient value K of magnetic field intensity normal component Hp(y) corresponding to crack decreases in the regular pattern of quadratic polynomial as burial depth increases. When burial depth is the same, gradient value K of magnetic field intensity normal component Hp(y) corresponding to crack increases as load increases. When burial depth is less, the influence of load on gradient value K is more obvious. When burial depth is bigger than 3.0 mm, advance the speed of gradient value K is relatively slow as load increases, and the difference in deformation capacity between laser cladding Fe314 alloy coating and 45 steel is seen as the main reason for above result.
