Wyniki wyszukiwania - BazTech

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Effect of Strain Range and Hold Time on High Temperature Fatigue Life of G17CRMOV5-10 Cast Alloy Steel

Polnik Anna, Matysiak Hubert, Czarnewicz Sławomir, Pakieła Zbigniew

Fatigue of Aircraft Structures

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2022

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Iss. 14

1--7

EN

In this work, cast steel G17CrMoV5-10 was investigated. The material subject to investigation as part of this study is commonly used to manufacture steam turbine casings. Modern steam turbines operate under elevated temperature and complex oscillated loads. Thus, the focus of this study was to investigate material under behavior during low cycle fatigue (LCF) test performance at 500°C with and without hold time in tension. During all types of test, cyclic softening of cast steel was noticed. Increasing of total strain rate and applying hold time significantly reduce fatigue life. During hold time, due to temperature and tension the material creep what is confirmed by increasing inelastic stain accommodation.

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Microstructural And Mechanical Properties Of Selective Laser Melted Inconel 718 For Different Specimen Sizes

Madejski Bartosz, Malicki Maciej, Czarnewicz Sławomir, Gruber Konrad

Fatigue of Aircraft Structures

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2020

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Iss. 12

15--26

EN

Selective laser melting (SLM) falls into the category of additive manufacturing technologies that are being increasingly used in the aerospace industry. This study presents the results of the examination of the microstructure and mechanical properties of selective laser melted Inconel 718. The tests were carried out for samples of different geometry (thickness, shape). The investigation showed the effect of the specimen’s size and the printing direction on the microstructure and mechanical properties. In the microstructural investigation, light and scanning electron microscopes were used. The microstructure investigation included measurements of the grain size and the carbides’ content. In order to estimate porosity computer tomography was used. Tensile tests were carried out at room temperature. The results showed differences in mechanical and microstructural properties of different size specimens.

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Determination of Stress Values in the Surface Layer of Inconel 718 Samples Dedicated to Fatigue Tests

Gadalińska Elżbieta, Michałowski Andrzej, Czarnewicz Sławomir

Fatigue of Aircraft Structures

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2019

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Iss. 11

78--86

EN

This work deals with the problem of X-ray stress determination on the samples dedicated to fatigue tests. A number of research studies point out the fact that the processing of hard, difficult to machine materials like nickel superalloys, reveals more than one trend of residual stress versus working parameters of behaviour (Lavella and Berruti, 2010). Many papers have shown that the residual stresses are dependent on a combination of a number of factors. When the above is taken into account simultaneously with the requirements of the internal General Electric specification for the fatigue tests samples preparation (Metallic test specimen preparation, low stress, 2017) the problem of turning and grinding parameters gathers significance. It is well known that the quality of the surface layer, produced during machining, is of vital importance for the fatigue life specially for the components of aircraft produced form nickel superalloys e.g. Inconel 718 (Kortabarri et al., 2011). That is why the surface layer’s properties are described in detail by the standards. The aim of the work is to determine one of the most influential features from the point of view of fatigue life, i.e. the stress state on the surface layer with one non-destructive method - the diffraction analysis.