|Andrzej Gazda, Marta Homa
This paper presents the results of measurements of thermal conductivity coefficient as a function of temperature for two species of spheroidal cast iron by using one of the most modern experimental sets LFA 427 (Laser Flash Apparatus) produced by Netzsch Company. In order to measure the specific heat cp(T) and density р(T), two methods of dynamic thermal analysis were used - differential scanning calorimetric DSC and dilatometric technique. Based on results of these measurements the coefficients of thermal conductivity were calculated with the use of Netzsch LFA Analysis software. Changes of slope of thermal diffusivity coefficient curvilinear dependence on temperature were observed, as well as rapid change on thermal conductivity λ(T) caused by thermal effect registered on cp(T) dependence. These observations allowed to identify decomposition process of ausferrite, caused from the disintegration of high-carbon retained austenite in ADI cast iron at approximately 400°C.
Keywords: thermal diffusivity, heat conductivity, specific heat, laser flash method (LFM), austempered ductile iron (ADI),
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Andrzej Gazda, Zbigniew Górny, Stanisława Kluska-Nawarecka, Krzysztof Saja, Małgorzata Warmuzek, Jacek Wodnicki, Robert Żuczek
The effect of heat treatment on structure and mechanical properties of B1044 (CuAl10Fe4Ni4) alloy was investigated. In the examined alloy, the content of aluminium, iron and nickel results in the formation of structure comprised in a boundary system between the regions of α + α2 + β’ and β’ + β1’ + α2 with the presence of γ2 phase formed due to eutectoid transfomation, affecting the level of mechanical properties. Before quenching, the specimens were preheated (solutioning heat treatment) for 2 h at 950°C, and different variants of cooling in water, oil and air were applied next. Some quenched specimens were also subjected to ageing from 500 or 700°C after 6 h heating and cooling with furnace and in the air. Very interesting results were obtained regarding both mechanical (Rm, R0,2) and plastic (A, Z) properties. Tests in the solid state were carried out using a dilatometer and differential calorimeter.
Keywords: bronze, heat treatment, mechanical properties, structure,
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Andrzej Gwiżdż, Krzysztof Jaśkowiec, Zenon Pirowski, Jacek Wodnicki
The study formed a part of industrial (applied) research executed under Target Project ROW-II-403/2008 at MAGNUS-NORD in Toruń. The aim of the study was to select the heat treatment parameters ensuring the required impact resistance values of GS-20Mn5 cast steel when operating at -30°C and -55°C. The study outlines the problem of alloy embrittlement when operating at low temperatures. Considering the production profile of „Magnus-Nord" Toruń, the study mainly regarded the possibilities of manufacturing under the conditions of this specific Foundry, the structural low-alloyed steel for castings operating at temperatures below -20°C. Consequently, the GS-20Mn5 steel was melted and, as a next step, parameters of the heat treatment of this alloy were selected to satisfy the requirements to obtain the required impact resistance at temperatures of -30°C (20-50J) and -55°C (20-30).
Keywords: ferrous alloys, heat treatment, impact resistance, embrittlement temperature, cast steel for operation at low temperatures,
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