Microstructure and mechanical properties of 316L composite formed by laser metal deposition and cold metal transfer

In order to achieve the complementary advantages of cold metal transfer（CMT） forming with high efficiency and laser metal deposition（LMD） forming with precision,it was proposed to combine CMT and LMD processes to manufacture parts with complex structures and high precision requirements in production. For 316 L stainless steel material in this paper,the CMT formed block samples were used as the base and the LMD formed composite samples were used on its different surfaces. The two additive manufacturing processes,microstructure and mechanical properties of the hybrid interface were compared through experiments. The results showed that the dendrite microstructures of the LMD and CMT formed samples appeared obvious epitaxial growth characteristics,and the primary dendrite spacing of LMD microstructure was significantly smaller than that of CMT microstructure. When the deposition directions of the two additive processes were parallel/vertical,a good metallurgical bond was formed at the hybrid interface. The tensile samples at the composite forming interface all fractured at the CMT part,which indicated that the mechanical properties at the hybrid interface were better than the CMT forming part.