Structural features of alloys manufactured by laser powder bed fusion

Abstract

Structural features of austenitic steel 316L and nickel alloy Ni-11%, Cr-5%, Co-6%, Al-3%, Ti-4%, Mo-5%, W-0.16%, C-0.02%, B (ZhS6K-VI) manufactured by laser powder bed fusion (L-PBF) were studied in this work. Alloys structures were formed under ultrafast cooling rates from the melt (105–107 K/s) and subsequent thermal cycling during re-melting of materials adjacent regions. It is known that such cooling conditions are nonequilibrium and can result in formation of nonequilibrium structures in alloys. The paper describes the features of such structures and some structural features for different alloys are considered: hierarchical structure, consisting of grains and subgrains; inhomogeneity of the distribution of alloying elements, accumulated at cell boundaries or secondary phases precipitation; high dislocations density with the cellular structure similar to those after plastic deformation; high macro stresses initiated cracking, and crystallographic texture resulted in anisotropy of mechanical properties.