Investigation of Microstructure and Mechanical Characteristics of Thin-walled Hastelloy C-276 Manufactured Through Pulsed-Arc Additive Manufacturing Technique

Abstract

Metal additive manufacturing is a significant and advancing manufacturing process on a worldwide scale. Wire + arc additive manufacturing (WAAM) is a progressed and efficient technique for producing large-scale near net shaped products by adding layers of material. This study presents pulsed current WAAM of a Hastelloy C-276 thin-wall component. The thin wall’s metallurgical and mechanical properties were extensively investigated. This included examining samples from different travel and build orientations. The microstructures in different areas include of columnar, cellular, and equiaxed dendrites. The temperature distribution and rate of cooling may impact the structure of the layers. The scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) investigation showed a high Ni content and low Mo and W in the dendritic core region (DCR). SEM and EDS examines on several areas showed no cracking in the thin wall’s travel and build orientations. In addition, the electron backscattered diffraction (EBSD) investigation showed that the average grain size was 66.38 μm in the (x-y) plane and 113.18 μm in the (y-z) plane. Reheating and solidification during layer-by-layer deposition altered grain characteristics. The hardness measurements exhibited variability across several locations. The existence of a well-defined directed dendritic microstructure, coupled with the presence of precipitates, provides corroborating evidence. The material has a maximum average ultimate tensile strength of 786 ± 6.1 MPa and elongation of 65.3 ± 3%. The fracture features are primarily ductile with periodic transgranular and intergranular behaviour. The pulsed current arc-based WAAM process offers a new and innovative method of depositing Hastelloy C-276. This method is applicable in chemical, nuclear, marine, and industrial sectors.

Graphical Abstract