Regularities of Formation of Lattice Structures Fabricated by Selective Laser Melting of Powdered 03Kh16N15M3 Steel

Abstract

This article discusses adjustment of processing modes of selective laser melting of powdered 03Kh16N15M3 steel allowing fabrication of lattice structures with steady parameters. On the basis of statistical analysis of sizes of cells, ribs, and nodes in cross section parallel to the growth direction of lattice structures of two sizes of ribs and voids (400 × 1000 and 300 × 600 μm), the process variables providing fabrication of items with the most stable sizes along the height of the structure have been determined. The sizes of the main elements of the lattice structure have been determined using a scanning electron microscope; the crystallographic texture and material structure have been determined using X-ray structural analysis. It has been determined that increase in laser power leads to increase in distortions in crystalline structure and decrease in the lattice constant of the material of lattice structures. The highest distortions of the structure have been detected in ribs of lattice structures as well as in items with smaller sizes of ribs and voids. The material of the considered lattice structures is characterized by axial texture, for which crystallographic axes are oriented parallel to the growth direction. The degree of manifestation of the axial texture component depends on the laser power used for growing of lattice structures. The samples obtained by minimum radiation power are characterized by a scattered axial texture, which is dictated by an increase in the number of chaotically oriented grains with a simultaneous decrease in the bulk of strictly oriented columnar crystals, located mainly in the vicinity of the axis of the ribs of the lattice structure. The texture sharpness in lattice samples with voids of small size is higher than that in samples with voids of large size.