Microstructural Heterogeneities in Electron Beam Additively Manufactured Haynes 282

Additive manufacturing(AM) has gained popularity due to the possibility of fabricating near net shapes of complex geometries with limited material waste and post processing. Haynes 282 is a precipitation strengthened Ni-based superalloy that has been found a good candidate for AM, such as electron beam powder bed fusion (PBF-EB), due to its good weldability that primarily comes from its low volume fraction of gamma prime (γ’) phase. Haynes 282 has applications in high temperature industrial gas turbine engines due to its thermal stability and high temperature creep resistance. Its improved performance at high temperatures has been attributed to the presence of the gamma prime (γ’) phase [1].

However, there are fundamental challenges related to the development of AM fabrication processes that need to be understood. PBF-EB processing can result in large thermal gradients and rapid temperature cycling. The resulting microstructure is a non-ideal columnar morphology commonly seen in AM that differs significantly from conventionally processed wrought alloys. In this work, microstructural heterogeneities in PBF-EB Haynes 282 were systematically characterized as a function of EBM-PBF process parameters such as build height, scan length, and scan velocity. Particular focus was on the size and morphology of the gamma prime (γ’) precipitates, MC carbides, and matrix gamma (γ) grains.