Browsing by Author "Turba, Krystof"

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    Determination of low temperature mechanical behaviour of the heat affected zone of a P91 steel weld using the small punch test technique
    (Ocelot Sro, 2012) Hurst, Roger; Turba, Krystof; Haehner, Peter; Matocha, K.; Hurst, R.; Sun, W.; Gülçimen, Betül; Durmuş, Ali; Ülkü, Sedat; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.
    The Small Punch (SP) test technique has been shown to be a promising method in determining the degradation of mechanical properties in operating components as it enables sampling from very localized areas; for instance the critical zones of a weldment and its HAZ (Heat Affected Zone). In this study, SP tests were carried out in order to determine the low temperature mechanical behaviour of the individual regions of P91 steel weld; base metal (BM), HAZ-FG (Heat Affected Zone-Fine Grained) and HAZ-CG (Heat Affected Zone-Coarse Grained). Microhardness measurements, optical and scanning electron microscopy methods were used for a better understanding of microstructure-property relationship and fracture mechanisms. As a result of the study it was possible to observe the increase in strength and ductility in the HAZ-FG compared to the BM and HAZ-CG which was more pronounced at lower temperatures. Consequently HAZ-FG had higher SP fracture energies and a lower transition temperature than the other zones.
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    Mechanical characterisation of a P91 weldment by means of small punch fracture testing
    (Elsevier, 2013) Hurst, Roger C.; Turba, Krystof; Hähner, Peter; Çakan, Betül Gülçimen; Durmuş, Ali; Ülkü, Sedat; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 36983839100; 55964532400; 6701921191
    Small Punch fracture tests were carried out in order to determine low temperature mechanical behaviour of a P91 steel weldment: weld metal, base metal, Heat Affected Zone-Fine Grained and Heat Affected Zone-Coarse Grained. The Heat Affected Zone-Fine Grained showed superior tensile properties in terms of displacement at fracture (ductility) and strength (maximum force) compared to the other zones, which became more pronounced at lower temperatures, whilst the weld metal exhibited inferior behaviour. Ductile Brittle Transition Temperatures were evaluated from Small Punch results for all zones and the results of base metal and weld metal were correlated with the transition temperatures obtained from Charpy V notch tests according to the CEN Code of Practice for Small Punch testing. Heat Affected Zone-Fine Grained with its finest structure exhibited the lowest transition temperature and the weld metal the highest. Heat Affected Zone-Coarse Grained and base metal were found to have quite similar transition temperature values.