| Abstract Scope |
AM-LPBF follows principles of welding processes, epitaxial grain extension bypassing nucleation followed by competitive grain growth/elimination, but the boundary conditions of LPBF are drastically different from typical welding which creates microscale solid-deposit in rapid solidification form. As a result, LPBF can produce unique properties by forming supersaturated solid solutions in the engineering final shapes, a quenched state without the structure being subjected to quench operation which is prune to distortion. Without altering the alloy compositions, ultrafine dispersoid can form in AM that doesn’t exist in the bulk metal manufacturing process. Both nickel base superalloy and niobium refractory, were investigated. All exhibited significant superior properties that their wrought equivalents couldn’t come close. For H230, a high Tungsten solid-solutions-strengthened-alloy, LPBF forms massive high-volume-fraction nanocarbides (WC) dispersively (CDS). For Nb C103, nano HfO was naturally formed, dispersively (ODS). With these strengthening mechanisms in the AM structure, break through materials properties were achieved.
|