Effect of rare earth elements on microstructure and properties of laser alloying layers on N80 oil tube

The N80 oil tube surface was preset with Ni-Cr-Ti-B4C- La2O3 alloying powders, the alloying layer which was metallurgically bonded with the base metal was obtained through laser treatment. The effect of rare earth elements on microstructure and properties of laser alloying layers on N80 oil tube was studied in this paper. The microstructure and microhardness of laser alloying layer were tested by optical microscopy (OM), scanning electron microscopy (SEM) and microhardness tester. The corrosion resistance was also tested by electrochemical corrosion testing equipment. The results show that the content of La2O3 affects the size and distribution of in-situ synthesis of TiB2 and TiC, hardness and corrosion resistance of laser alloying layers. When the content of La2O3 is 0.5%, the properties of laser alloying layers are improved, such as the reinforcing phase of TiB2 and TiCis tiny and well-distributed, the hardness is highest, and the corrosion resistance is also enhanced.