Processing parameter and transient effects on melt pool geometry in additive manufacturing of Invar 36

The use of additive manufacturing (AM) in tooling enables low production components to be fabricated with lower costs, reduced waste, increased design flexibility, and reduced lead time. Invar 36 is a popular metal tooling material known for its low coefficient of thermal expansion. This work uses thermal finite element modeling as a tool to determine the feasibility of using the Invar 36 in the AM and to investigate the transient effect from a common stripe scanning strategy used in laser powder bed fusion (LPBF) AM. Modeling results show that the steady-state melt pool dimensions behave similarly to traditional AM materials with the same base materials when varying process parameters within the range of LPBF. Single bead and multiple laser pass experiments were performed to compare to the modeling results and determine additional transient effects resulting from repeated scans. Results show that the Invar 36 is a suitable material for use in the AM, which will enable rapid tooling for composite structures.