Effects of scanning pattern on the grain structure and elastic properties of additively manufactured 316L austenitic stainless steel

Abstract

The present paper aims to contribute to the understanding of the process-(micro)structure-property linkage in additively manufactured materials. The scanning pattern effects on the microstructure and elastic properties of 316L austenitic stainless steel produced by the powder bed based additive manufacturing are explored. A multiphysics methodology adapted for this purpose combines the physically-based cellular automata for simulation of the grain structure evolution, finite-difference heat transfer calculations in a simplified way following the concept of a moving melt pool, and elastic anisotropy modeling based on the orientation distribution functions and Reuss, Voigt, and Hill schemes. Unidirectional and bidirectional scanning strategies strongly influence the texture and elastic properties of as-built components. The grain structures obtained are characterized by bi-component crystallographic textures. While the specimen printed using a bidirectional strategy demonstrates the major 011100 Goss and minor 001100 cube texture components, the unidirectional scanning pattern leads to the rotation of both grain arrangement in space and crystallographic texture. The specimen produced with a unidirectional strategy tends to have coarser grains, more severe texture and more pronounced anisotropy of elastic properties than that printed using a bidirectional scanning pattern. The latter is concluded to exhibit the orthotropic behavior based on the calculated stiffness tensor. In addition, the present study reports stiffness tensors for the additively manufactured steel components.