Interface analysis of additively manufactured pure molybdenum and AISI 304 stainless steel building-plate

In this study pure molybdenum was produced by laser powder bed fusion on an AISI 304 building-plate. Adhesion issues were found at the interface between the two materials since the very beginning of the production process. Interface analysis was performed in order to investigate possible origins of the failure. The investigation showed that large cracks could propagate and led to separation of the printed part from substrate when the dilution of Mo on AISI 304 platform was approximately in the range 40 ÷ 50. The brittle intermetallic sigma phase was extracted and analysed by XRD on Mo-AISI 304 interface specimens. It is assumed that the sigma phase impaired the interface strength, providing a preferential route for brittle crack propagation.