Studium struktury a vlastností tvářených polotovarů připravených alternativními způsoby výroby

Abstract

This dissertation is focused on study of the structure and properties of preforms produced by the additive technology of selective laser melting (SLM), and their optimization through subsequent thermomechanical processing using rotary swaging. The research primarily investigates two experimental materials, stainless steel AISI 316L and the nickel based superalloy Inconel 718. The aim was to thoroughly analyze microstructure, porosity, residual stresses, and the effects of various subsequent processing temperature conditions on the mechanical behavior of the preforms. The results revealed that rotary swaging applied at three temperatures levels led to significant homogenization and improvement of properties in the additively manufactured parts. For the AISI 316L steel, microstructure refinement at < 1 μm, and increased strength and microhardness (up to 2100 MPa and 547 HV1 after cryogenic conditions) were achieved. Rotary swaging also resulted in homogenized and reduced residual stresses and lower porosity. By hot rotary swaging of Inconel 718 likewise had a positive impact on final properties, with significant microstructure refinement and reduction of residual deformation, residual stress, and initial porosity from 1.1 % to 0.1 % after the first pass. The mechanical properties and microstructure after rotary swaging in some cases approach or even overcome those of conventionally manufactured materials, mainly due to the elimination of defects and a more homogeneous microstructure.