Simultaneously Improving the Strength and Plasticity of Additively Manufactured 316L Stainless Steel by Adding Aluminum

Abstract

Due to the special layer‐by‐layer printing process of additive manufacturing (AM), the heat dissipation in the printed material tends to flow mainly along the building direction, which results in the formation of coarse columnar grains in AM metals. The coarse grains are detrimental to the mechanical properties of AM metals, and are not conducive to the lightweight development of AM metal components. This article proposes a printing strategy for adding aluminum to 316L stainless steel. Based on the aluminum‐reinforced strategy, low melting point MnSiO3 particles are transformed into high melting point Al‐containing particles (such as Al2O3), and the grain size of 316L stainless steel produced by direct energy deposition (DED) is refined, resulting in a significant improvement of tensile strength. What is more, the increase in tensile strength of Al‐reinforced 316L does not sacrifice its plasticity. Attributed to the twinning‐induced plasticity effect and good adhesion between Al2O3 particles and matrix, the plasticity of Al‐reinforced 316L is synchronously improved. To be more specific, compared to DED‐316L without adding Al, the yield strength and tensile strength of samples with adding 0.5%wt Al are individually improved by 14.8% and 16.2%; at same time, the uniform elongation and total elongation are increased by 80.4% and 13%, respectively. The printing strategy proposed in this article is expected to provide reference for the strengthening and toughening of AM metals, thereby contributing to the lightweight development of AM components.