Orientation, dendrites and precipitates in Hastelloy C276 alloy fabricated by laser and arc hybrid additive manufacturing

In this work, Hastelloy C276 alloy with exceptional strength and ultra-high elongation is fabricated using laser and arc hybrid additive manufacturing (LHAM). The specimen undergoes solution treatment at 1177 °C for 30 min, followed by water quenching. Compared to wire arc additive manufacturing (WAAM), LHAM significantly refines columnar grains, reduces P-phase precipitates, and decreases texture strength, attributed to the increased cooling rate from laser application. The LHAM specimen exhibits improved tensile strength, likely due to smaller grain size, higher dislocation density, and reduced precipitate content. Further heat treatment (LHAM-HT) results in reduced texture strength, equiaxed grains with annealing twins and no precipitates detected. The LHAM-HT specimens show lower hardness and yield strength (190.33 HV and 338 MPa) due to dislocation annihilation, but enhanced elongation and tensile strength (63.5% and 713 MPa) owing to fine grain size and absence of precipitates. The lower yield-to-tensile strength ratio suggests improved safety, and a high number of Σ3 grain boundaries indicates excellent mechanical properties. This research highlights that LHAM, paired with suitable heat treatment, can effectively produce high-performance Hastelloy C276 alloy, offering a practical approach to nickel-based alloy additive manufacturing.