Bimetallic structure formation by Laser Powder Bed Fusion

Abstract

Bimetallic structures are an excellent solution for a lot of engineering applications which require varying properties at different locations of the same object. Implementation of such structures into engineering fields can lead to easier maintenance, economical and space savings and can also open wider application possibilities. In recent years, production of bimetallic structures has been made possible with help of additive manufacturing (AM) technologies. Using laser powder-bed fusion AM, bimetallic structures can be created by depositing different materials in a layer-by layer fashion.In this work, two materials in powder form were used for bimetallic structure formation – CoCrMo and 17-4 PH stainless-steel. The bimetallic structure was successfully produced by using the L-PBF technology applied in EOSINT M280 machine. In-depth analysis of the 17-4 PH and CoCrMo materials and microstructural properties of the produced bimetallic sample were investigated in this study. A gradual change in chemical element distribution is observed at the two-material fusion zone. The thickness of the fusion zone is around 400-450 µm. The hardness of the fusion zone (104±2 HRB) is higher than the hardness of 17-4 PH (95±2 HRB) but lower than CoCrMo (111±2 HRB). The experimentally evaluated density of the bimetallic specimen is 8.01 g/cm3. The difference in values proves that the fusion zone of the specimen possesses unique characteristics that are not specific to either of the materials.