Analysis of AISI 316L-Ti Graded Deposition Fabricated by Wire and Arc Additive Manufacturing

Manufacturing of steel and titanium-based bimetallic material using cold metal transfer-based wire arc additive manufacturing (CMT-WAAM) is a novel exploration. It can be helpful in on-line repairing of dissolver tank piping in nuclear reactor power plants. In the present work, owing to the unique characteristic of lower heat input, CMT-WAAM was used for fabrication of AISI 316L-Ti graded structure on the AISI 316L substrate. The deposition shows apparent cracks and delamination at the bimetallic interface. The interface microstructure mainly consists of Fe-Ti intermetallic compounds (IMCs) of cellular and dendritic shapes and their boundaries were wetted by Cr-Ti IMCs. However, the cellular grains were fine and equiaxed and there was no evidence of presence of large columnar grains. EDS results show that the total graded region was of approx. 6 mm and Fe shows deeper penetration into Ti due to lesser requirement of activation energy. The presence of brittle IMC phases was also confirmed by the XRD analysis.