激光金属沉积与冷金属过渡复合成形316L的组织与力学性能

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

为了实现冷金属过渡(CMT)成形高效和激光金属沉积(LMD)成形精细的优势互补,提出将CMT与LMD 2种工艺复合的方法,用于制造生产中结构复杂、精度要求高的零件,该文针对316L不锈钢材料,以CMT成形样块作为基底,在其不同表面上采用LMD成形复合试样,通过试验对比2种增材制造工艺及结合界面处的显微组织与力学性能。结果表明,LMD与CMT各自成形试样的枝晶组织均呈现明显的外延生长特性,且LMD组织一次枝晶间距明显小于CMT组织。2种增材工艺沉积方向平行/垂直时,结合界面处均形成了良好的冶金结合。复合成形界面处拉伸试样均断裂于CMT部分,说明结合界面处力学性能优于CMT成形部分。

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 316L 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.