Speaker: G.T. (Rusty) Gray III

Materials Science and Engineering Division, Los Alamos National Laboratory

“Characterization of Additively Manufactured (AM) 316L and 304L SS”

G.T. (Rusty) Gray III, J. Carpenter, V. Livescu, C.P. Trujillo, C. Knapp, D. Jones

Materials Science and Engineering Division

Abstract:

For additive manufacturing (AM) of metallic materials, the certification and qualification paradigm needs to evolve as there currently exists no broadly accepted “ASTM- or DIN-type” additive manufacturing certified process or AM-material produced specifications.  Accordingly, design, manufacture, and thereafter implementation and insertion of AM materials to meet engineering applications requires detailed quantification of the constitutive (strength and damage) properties of these evolving materials, across the spectrum of metallic AM methods, in comparison/contrast to conventionally-manufactured metals and alloys.  This talk summarizes the 316L SS research results and presents initial results of the follow-on study of 304L SS.

For the AM-316L SS investigation, cylindrical samples of 316L SS were produced using a LENS MR-7 laser additive manufacturing system from Optomec (Albuquerque, NM) equipped with a 1kW Yb-fiber laser.  The microstructure of the AM-316L SS was characterized in both the “as-built” Additively Manufactured state and following a heat-treatment designed to obtain full recrystallization to facilitate comparison with annealed wrought 316L SS.  The dynamic shock-loading-induced damage evolution and failure response of all three 316L SS materials was quantified using flyer-plate impact driven spallation experiments at peak stresses of 4.5 and 6.35 GPa.

Following on from the 316L SS completed work, initial results on a study of AM 304L SS are in progress and will be presented.  Preliminary results on the structure/dynamic spallation property behavior of AM-304L SS fabricated using both the directed-energy LENS and an EOS powder-bed AM techniques in comparison to wrought 304L SS is detailed.  The damage evolution as a function of AM fabrication method was characterized for the 316L and 304L SS using optical metallography and electron-back-scatter diffraction (EBSD).