Examination of erosion wear behavior of AlSi10Mg alloy produced by additive manufacturing and casting methods in cryogenic environments

In this thesis, the erosion wear behaviour of AlSi10Mg alloys produced by metal additive manufacturing method, which is preferred in sectors such as aviation, aerospace, automotive, agriculture, mining, medical and dentistry, has been investigated. In order to compare additive and conventional manufacturing methods, test specimens were produced by selective laser melting method and aluminium injection casting method, which are powder-based additive manufacturing applications. The effect of heat treatment on erosion behaviour was investigated by applying heat treatment (T6) to a group of specimens produced for repeated tests. Silicon Carbide (SiC) erosive particles with a size of ~350 µm were used to determine the effect of particle effect in erosion tests and solid particle erosion wear results were obtained for different parameters. In order to determine the impact velocity of erosive particles on the surface of the target material, the air flow velocity was found to be 60 m/s with a sensor. In the determination of the velocities of particles at the moment of mixing with air, the free fall velocity was determined to be approximately 2,24 m/s by simulations based on Discrete Element Method (DEM). The values measured by simulation and sensor were combined with Euler's Langerian Particle Tracking (LPT) flow model to theoretically calculate the particle impact velocity of ~25 m/s. Particle impact velocity was also measured by double disc method and theoretical and experimental convergence results were obtained. Another important parameter among the solid particle erosion wear parameters, the impact angle, was compared using six different impact angles (15° to 90° constant increase). The experiments were carried out at room temperature and cryogenic ambient conditions (≤-100°C). In order to ensure cryogenic conditions, cryogenic conditions were verified with sensor sensitivity by providing controlled contact of the test samples in certain groups with liquid nitrogen (-196°C) in a styrofoam closed chamber capable of representing the container feature. The experiments were carried out on a specially designed test machine capable of ASTM G76/G211 standards and the impact angle- erosion rate graphs were created at end of the impact angle- erosion rate graphs at end of the weight loss data and alternative manufacturing method, heat treatment effect comparisons in the priority of international literature compatibility. Correlation analysis was applied in order to make sense of the erosion wear behaviour of the test specimens and to provide statistical data. In order to compare the results obtained from the experiments, discrete element based simulation activities were carried out with Ansys Rocky DEM software on non-heat treated additive manufacturing specimens and simulation related erosion rates were calculated and it was understood that the relevant software can be useful within various limits in determining the erosion rate. After the completion of all experiments with three repetitions, SEM images were taken from the surfaces of the eroded samples at various magnification scales and XRD analysis was applied to the samples. As a result of the surface analyses, it was observed that surface structure was intensely degraded due to plastic deformation on the surfaces and collapses, particle embedment and crushing marks were observed on the surfaces as a result of interaction with particles. The resulting surface damages support the ductile and fully ductile material characteristics obtained from erosion tests. Within the scope of presenting outputs of this thesis study, it has been concluded that AlSiMg10 alloys produced by additive manufacturing can provide more erosion resistance than those produced by conventional manufacturing methods in terms of solid particle erosion wear results depending on experimental activities and simulation studies. It is also determined that T6 heat treatment improves the erosion wear resistance of AlSi10Mg samples produced by additive manufacturing. Finally, cryogenic conditions were also found to increase the amount of solid particle erosion wear.