AM Fabrication Of Tool Steel From Water Atomized Powder Blends By Electron Beam Powder Bed Fusion

Abstract

Customarily, gas atomized, pre-alloyed metal powders are employed in PBF processes. Transition to water atomized powder has the potential for higher resource efficiency and lower costs. Since steel grades with higher content of alloying elements are often not water atomized, powder blends with master alloys are considered.For this study, 80% of water atomized low-carbon steel powder was blended with 20% gas atomized master alloy, such that the composition of 1.2343 is reached. The blend quality and segregation behavior were characterized. After optimization of PBF-EB parameters, the chemical composition and homogeneity were analyzed.Metallographic cross-sections revealed relative densities of 99.8%. The master alloy fraction has a distinct influence on the content of alloy elements. The homogeneity of the alloy distribution is influenced by scanning parameters. Slower scan speed causes larger melt pools and homogeneous elemental distribution. The tensile strength reaches 1753 MPa, close to material fabricated from pre-alloyed powder.