Study Of The Damage Failure And Mechanical Response Of The Laser Coat Under Repeated Impact

There are many components which are working under the repeated impact load in project. All kinds of defects appear in the surface of components which under the repeated impact load, and the surface defects make the earlier damage and failure. The research adopts laser cladding to make a new coat on the surface of the component, which can enhance the surface's capability of resisting repeated impact and extend the service life. There are repeat impact experiments on self-made repeated impact test instrument with samples which are laser melt Co-based, Ni-based and Fe-based on 1Cr18Ni9Ti steels, 45 steels and 40Cr steels bases. Carry out the failure analyses with TEM-H-600-2,SEM-S-570,OLYMPUS GX51F microscope instruments, and analyzing failure influencing factors. The dynamic response of the samples is studied with the theory of impact dynamics. The mechanical response of the samples is analyzed with FEM. The stress wave in the sample will change with the propagation distance. It is reduced by an exponential form. The compressive stress wave will change into tensile stress wave on the combined interface of sample with full coat when it is reflected. It is concerned with the relative area of the base and coat that the compressive stress wave will change into either tensile stress wave or compressive stress wave when it is reflected in the sample with part coat. It is suggested that the damage and failure occurred on the surface of the coat primarily, which is fatigue wear (included corrosive pitting, collapse and sheet erosion), crackle and hardened or softened. The mechanical models are established with FEM under varied loads, varied materials of coat and base, varied covered form. The results indicate that the strain in the sample of Fe-based coat is larger than of Ni-based coat. The deformation of the sample with full coat is larger than that of the sample with part coat under the same load and same materials, but the maximum stress in the sample with full coat is smaller than that in the sample with part coat.