Jaroslaw Kurzac

Bio: Jaroslaw Kurzac is an academic researcher from Wrocław University of Technology. The author has contributed to research in topics: Selective laser melting & Ultimate tensile strength. The author has an hindex of 2, co-authored 3 publications receiving 377 citations.

Effect of heat treatment on the microstructure and mechanical properties of Inconel 718 processed by selective laser melting

Abstract: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder. High- density (99.8%) cylindrical specimens were built with four orientations (0°, 45°, 45°×45° and 90°) in relation to the building and scanning directions. Because of directional, dendritic-cellular grain growth, microstructure of the as-built specimens was characterized by columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions. Such a heterogeneous microstructure is unsuitable for direct post-process aging and makes the alloy sensitive to subsolidus liquation during rapid heating to the homogenizing temperature. In homogenized and aged condition, the alloy received a very good set of mechanical properties in comparison with the wrought material. In heat-treated condition, like in as-built condition, weak anisotropy of properties was found, manifested by lower Young's modulus, yield strength and tensile strength of the specimens extended along the build direction in comparison to the values for the other variants of the specimens. This is attributed to the fact that the grains maintained their geometric and crystallographic texture obtained during solidification.

Fatigue crack growth rate and tensile strength of Re modified Inconel 718 produced by means of selective laser melting

Abstract: The paper presents results of mechanical tests, namely fatigue crack growth (FCG) rate and tensile tests – of Inconel 718 produced by Selective Laser Melting (SLM) in pure form and with Re addition SLM method was used to manufacture “comb like” structures, simulating small parts with thin walls, of which final mini-samples were cut out (two types of samples for tensile and one for the FCG rate test were used) A fraction of samples underwent a standard procedure of a heat treatment designed for Inconel 718 alloy The influence of samples orientation to the laser beam direction, samples size and heat treatment on the tensile strength, yield strength and elongation to fracture were investigated FCG rate tests were carried out using mini-samples with notches Cyclic loading of samples was synchronized with CDD camera trigger for registering images of samples surfaces at the moments of maximal loading Digital Image Correlation (DIC) was used to determine near crack tip displacement fields The results of DIC measurements were analyzed using the inverse method to automatically determine the stress intensity factor and crack tip coordinates Additionally, fracture surfaces SEM observations, X-ray Diffraction (XRD) analyses, X-ray fluorescence (XRF), light microscopy (LM) and Transmission Electron Microscopy (TEM) observations have been done to understand mechanical properties variation revealed during mechanical testing

Influence of laser power on the penetration depth and geometry of scanning tracks in selective laser melting

Abstract: SLM technology allows production of a fully functional objects from metal and ceramic powders, with true density of more than 99,9%. The quality of manufactured items in SLM method affects more than 100 parameters, which can be divided into fixed and variable. Fixed parameters are those whose value before the process should be defined and maintained in an appropriate range during the process, e.g. chemical composition and morphology of the powder, oxygen level in working chamber, heating temperature of the substrate plate. In SLM technology, five parameters are variables that optimal set allows to produce parts without defects (pores, cracks) and with an acceptable speed. These parameters are: laser power, distance between points, time of exposure, distance between lines and layer thickness. To develop optimal parameters thin walls or single track experiments are performed, to select the best sets narrowed to three parameters: laser power, exposure time and distance between points. In this paper, the effect of laser power on the penetration depth and geometry of scanned single track was shown. In this experiment, titanium (grade 2) substrate plate was used and scanned by fibre laser of 1064 nm wavelength. For each track width, height and penetration depth of laser beam was measured.

Microstructure and hardness studies of Inconel 718 manufactured by selective laser melting before and after solution heat treatment

Abstract: The microstructure of Additive Manufactured (AM) Inconel 718 in general and Selective Laser Melting (SLM), in particular is different from the material produced by conventional methods due to the rapid solidification process associated with the former. As a result, the widely adapted standard solution heat treatment temperature (

Overview on Additive Manufacturing Technologies

Abstract: This paper provides an overview on the main additive manufacturing/3D printing technologies suitable for many satellite applications and, in particular, radio-frequency components. In fact, nowadays they have become capable of producing complex net-shaped or nearly net-shaped parts in materials that can be directly used as functional parts, including polymers, metals, ceramics, and composites. These technologies represent the solution for low-volume, high-value, and highly complex parts and products.

Microstructure and mechanical properties of Inconel 718 produced by selective laser melting: Sample orientation dependence and effects of post heat treatments

Abstract: Inconel 718 produced by selective laser melting (SLM) has been characterized with focus on the microstructure, the dependence of sample orientation on the mechanical properties and the effects of post heat treatments. The as-manufactured IN718 has a very fine cellular-dendritic structure with fine Laves phases precipitating in the interdendritic region, and electron backscatter diffraction (EBSD) analysis shows that both the vertically and horizontally built samples have relatively weak texture. The vertically built samples show lower tensile strength but higher ductility than the horizontally built samples, and the mechanism is shown to be partly due to the crystallographic feature but more importantly due to the different amount of residual stress and dislocations accumulated in these two kinds of samples. Applying heat treatments can significantly increase the strength while decrease the ductility correspondingly, and difference in yield strength between the vertically and horizontally built samples decreases with increasing the heat treatment temperatures, mainly due to the removal of residual stress and dislocations.