Influence of Porosity on Fatigue Behaviour of 18Ni300 Steel SLM CT Specimens at Various Angles

Cerezo, Pablo M.; Aguilera, Jose A.; Garcia-Gonzalez, Antonio; Lopez-Crespo, Pablo

doi:10.3390/ma17020432

Cited by 3 publications

(3 citation statements)

References 49 publications

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“…According to previous research [45], the distribution of the atomic composition of pores does not result in an uneven precipitation of alloy elements. In this research, all elements maintained a stable distribution with a slight reduction in the case of Fe and an increase in Ni when moving away from the centre of the pore.…”

Section: Resultsmentioning

confidence: 68%

“…Previous research has found pores of 5-10 µm in diameter on 2D sections [45], so in order to ensure accurate characterisation testing, it is necessary to reduce the resolution of the sample enough to account for the existence of pores. A small parallelepiped from the overall specimen was extracted from the surface of the specimen.…”

Section: Defects Characterisationmentioning

confidence: 99%

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Tomography of Laser Powder Bed Fusion Maraging Steel

Cerezo,

Aguilera,

Garcia-Gonzalez

et al. 2024

Materials

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The presence of defects in additive manufactured maraging steel is a widespread problem as its dependence on processing parameters significantly influences it. Using X-ray computed tomography, along with optical microscope data limited to 2D images, quantifies the internal porosity present on a compact tension sample typically employed in fatigue testing. The primary goal of this research is to analyse the pores obtained after the fabrication of a compact tension sample and their main definition parameters, such as sphericity, aspect ratio, surface, and volume, and obtain validation of which method is valid for each of the parameters analysed. The current study aims to enhance the understanding of defects in maraging steel samples through non-destructive 3D analysis. Conventional 2D analyses are limited to surface measurements, providing incomplete information. The proposed method will provide a comprehensive understanding of the defects inside the maraging steel sample, thereby improving the reliability of this material for further applications. This study will contribute to academic and industrial communities by providing a novel approach to analysing maraging steel samples and, ultimately, developing improved materials for various applications. The study’s findings reveal that most pores are produced by gases that are trapped in the fabrication process, and keyhole pores only appear near the surface.

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Section: Resultsmentioning

confidence: 68%

Section: Defects Characterisationmentioning

confidence: 99%

Tomography of Laser Powder Bed Fusion Maraging Steel

Cerezo,

Aguilera,

Garcia-Gonzalez

et al. 2024

Materials

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“…This procedure aimed to ascertain the microstructure and morphology of the grains using an optical microscope (OM), the Leica DM 6 M OM (Wetzlar, Germany). Density measurements were performed by taking an image of the whole surface through the OM in bright field and using ImageJ v1.53t to calculate the percentage of surface area excluding gas pores and lack of fusion, obtaining a porosity of 0.187% of the total area [43].…”

Section: Methodsmentioning

confidence: 99%

Microhardness and Microstructure Analysis of the LPBF Additively Manufactured 18Ni300

Cerezo,

Aguilera,

Garcia-Gonzalez

et al. 2024

Materials

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This research focuses on analysing the 18Ni300 maraging steel produced through laser powder bed fusion. Specifically, it aims to examine the phase components using X-ray diffraction, the microstructure through scanning electron microscopy, and the hardness of the different structures present in the manufactured material. The primary goal is to meticulously analyse the material and its microstructures. By doing so, a correlation between the hardness and each structure type, be it cellular or columnar, can be established. This will allow us to pinpoint any defects in the material before any surface chemical treatment is carried out and facilitate a thorough examination of its microstructure. A consistent pattern emerges across the samples through systematic measurement of microhardness distribution in various locations and detailed examination of the structure. The findings of the study reveal that the hardness of cellular and columnar structures exhibits a significant variation based on the location of the measurement about cell boundaries. The hardness value is notably higher in the combination of cellular and multiple layers, as the data indicate.

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Controlled Porosity of Selective Laser Melting-Produced Thermal Pipes: Experimental Analysis and Machine Learning Approach for Pore Recognition on Pipes Surfaces

Malashin,

Martysyuk,

Tynchenko

et al. 2024

Sensors

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This study investigates the methods for controlling porosity in thermal pipes manufactured using selective laser melting (SLM) technology. Experiments conducted include water permeability tests and surface roughness measurements, which are complemented by SEM image ML-based analysis for pore recognition. The results elucidate the impact of SLM printing parameters on water permeability. Specifically, an increase in hatch and point distances leads to a linear rise in permeability, while higher laser power diminishes permeability. Using machine learning (ML) techniques, precise pore identification on SEM images depicting surface microstructures of the samples is achieved. The average percentage of the surface area containing detected pores for microstructure samples printed with laser parameters (laser power (W) _ hatch distance (µm) _ point distance (µm)) 175_ 80_80 was found to be 5.2%, while for 225_120_120, it was 4.2%, and for 275_160_160, it was 3.8%. Pore recognition was conducted using the Haar feature-based method, and the optimal patch size was determined to be 36 pixels on monochrome images of microstructures with a magnification of 33×, which were acquired using a Leica S9 D microscope.

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Influence of Porosity on Fatigue Behaviour of 18Ni300 Steel SLM CT Specimens at Various Angles

Cited by 3 publications

References 49 publications

Tomography of Laser Powder Bed Fusion Maraging Steel

Tomography of Laser Powder Bed Fusion Maraging Steel

Microhardness and Microstructure Analysis of the LPBF Additively Manufactured 18Ni300

Controlled Porosity of Selective Laser Melting-Produced Thermal Pipes: Experimental Analysis and Machine Learning Approach for Pore Recognition on Pipes Surfaces

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