Interplay between microstructure, micromechanical, and tensile properties in wire arc additive manufactured nickel-aluminum bronze: As-built and heat treated

The generalized hardness-strength relationship in additively manufactured materials may differ from that observed in cast/wrought materials. To investigate this, the present study focuses on wire-arc additive manufactured (WAAM) Nickel-Aluminum Bronze (NAB) in both its as-built state and three distinct heat-treated conditions. Tensile tests and nanoindentation hardness tests were conducted simultaneously to establish a correlation between hardness and strength. Additionally, a comparison is made between the cast-NAB material and WAAM-NAB in this article. By considering the variations in grain size (coarse vs. fine) and intermetallic compounds in the cast and WAAM-NAB materials (in their as-built and post-heat treated forms), the correlation factor is found to differ based on the specific manufacturing processes and heat treatments employed. This paper aims to develop empirical equations that account for the various influencing factors, including rigid plasticity and uniform plastic work hardening conditions. Moreover, the study reports several indentation-based quantitative variables, such as the plasticity index, elastic recovery, recovery resistance, and wear resistance index of the WAAM-NAB material. By providing a comprehensive analysis of these factors, this research contributes to a better understanding of the hardness-strength relationship and the associated material properties in WAAM-NAB.