Multi-objective optimisation of process parameters for laser-based directed energy deposition of a mixture of H13 and M2 steel powders on 4Cr5Mo2SiV1 steel

Abstract

ABSTRACT In present paper, a universal method for multi-objective parameter optimisation of additive manufacturing processes was proposed and successfully applied to laser-based directed energy deposition (DED) experiments with mixtures of H13 and M2 steel powders that were deposited on 4Cr5Mo2SiV1 hot work die steel. The DED experiments were designed and completed based on the response surface method with 13 groups of laser parameters. The microstructure of the deposited alloy steel was observed and its mechanical properties were tested. The deposited steel alloy achieved an ultimate tensile strength (UTS) of 1821 ± 30 MPa with a reasonable elongation of approximately 4.5%, and the bond strength specimens achieved a bond toughness of ∼10.66% with a moderate UTS (1329 ± 28 MPa). A multi-objective optimisation method was proposed based on response surfaces which were established according to microstructural characteristics and mechanical properties data. It provided a basis for achieving high strength or high toughness DED-fabricated steel alloys.