## 1 Introduction  
The 316L stainless steel provides excellent corrosion resistance and good toughness, and has been extensively applied in the marine, medical, machinery, oil and gas pipeline industries, and other fields [1, 2, 3]. However, as austenitic stainless steel, the low hardness and poor wear resistance of 316L stainless steel limit its wider application [4, 5, 6, 7]. Surface strengthening techniques such as carburizing, nitriding, local heat treatment, and shot peening have been employed in practical applications to improve the surface properties of 316L steel [8, 9]. [PERSON] et al. [10] investigated the effect of shot peening intensity on the surface integrity and fatigue life of 316L stainless steel. The microhardness was increased from 316 HV to 435 HV. The fatigue life was significantly improved. [PERSON] et al. [11] adopted cryogenic gas carburizing technology to improve the hardness of 316L steel. The thickness of the carburizing layer was about 30 \(\upmu\)m, and the fatigue life was increased by about 28%. [PERSON] et al. [12] adopted different nitriding pressure, nitriding distance, and pressure to strengthen the surface of 316L stainless steel. The thickness of the nitriding layer can be adapted from 7 \(\upmu\)m to 16 \(\upmu\)m. However, the surface of parts peened by shot peening, carburizing, and nitriding techniques is generally restricted by the limited improved wear resistance and poor bond strength to the substrate. In recent years, with the boom in laser additive manufacturing (AM) technology, laser cladding has become a leading technology because it can be employed to improve the hardness, wear resistance, and corrosion resistance of metal parts [13, 14, 15]. Compared with the traditional surface strengthening technology, the coating fabricated by laser cladding has the advantages of a low dilution rate, good metallurgical bond performance, and controllable microstructure and mechanical properties [16; 17]. As a kind of composite material, metal-matrix composites provide both the wear resistance of ceramics and the toughness of matrix. It has attracted the attention of many academics and research teams. [PERSON] et al. [18] fabricated WC-reinforced 316L alloy composites with different volume fractions by using laser AM. Results showed that the microhardness of the composites was increased by 92%. However, the addition of WC also increased the crack sensitivity and porosity of the composites. [PERSON] et al. [19] explored the effects of different laser energy densities on the microstructure and mechanical properties of nano-TIC/316L composites by combining simulation and an experiment. The appropriate laser energy density can refine the microstructure and reduce the wear rate of the composites. [PERSON] et al. [20] prepared an NbC-reinforced composite coating on the surface of a 316L stainless steel cardiovascular support, and test results showed that the hardness, elastic modulus, and wear resistance of the composite coating were superior to those of 316L stainless steel. Therefore, the fabrication of particles-reinforced composites by laser cladding is an effective way to improve the hardness and wear resistance of 316L stainless alloy. Reviewing the above literature, the addition of single ceramic particles often leads to agglomeration of ceramic particles, which is detrimental to improving the uniformity of the mechanical properties of the coating. Research [14; 21] also indicates that TiC and NbC ceramics with high hardness, wear resistance, and thermal stability, can be considered as ideal candidates to strengthen the mechanical properties of 316L alloy. In addition, because TiC and NbC have similar lattice structures, Ti and Nb atoms in the lattice structure can be exchanged to form multi-carbide ceramics during the solidification process [16; 22]. Therefore, the floating up phenomenon of low-density TiC can be suppressed effectively, leading to more uniform microhardness and mechanical properties.