Mechanical Properties And Creep Resistance Of Nickel Alloys After Complex Modification And Double Filtration

The paper presents the results of studies to determine the effect of complex surface and bulk modification and double filtration during mould pouring on the stereological parameters of macrostructure and mechanical properties of castings made from the post-production waste IN-713C and the MAR-247 nickel alloys. The evaluation covered the number of grains per 1mm2 of the sample surface area, the average area of grains and the shape index, hardness HB, tensile strength and resistance to high temperature creep. The results indicate the possibility of controlling the stereological parameters of macrostructure through application of several variants of the modification, controlling in this way also different low- and high-temperature properties. The positive effect of double filtration of the alloy during mould pouring on the metallurgical quality and mechanical properties of castings has also been emphasized

Ceramic filters for bulk inoculation of nickel alloy castings

The work includes the results of research on production technology of ceramic filters which, besides the traditional filtering function, playalso the role of an inoculant modifying the macrostructure of cast nickel alloys. To play this additional role, filters should demonstratesufficient compression strength and ensure proper flow rate of liquid alloy. The role of an inoculant is played by cobalt aluminateintroduced to the composition of external coating in an amount from 5 to 10 wt.% . The required compression strength (over 1MPa) isprovided by the supporting layers, deposited on the preform, which is a polyurethane foam. Based on a two-level fractional experiment24-1, the significance of an impact of various technological parameters (independent variables) on selected functional parameters of theready filters was determined. Important effect of the number of the supporting layers and sintering temperature of filters after evaporationof polyurethane foam was stated

Evaluation of Metallurgical Quality of Master Heat IN-713C Nickel Alloy Ingots

The paper presents the results of evaluation of the metallurgical quality of master heat ingots and of the identification of non-metallic inclusions (oxides of Al., Zr, Hf, Cr, etc.), which have been found in the shrinkage cavities formed in these ingots. The inclusions penetrate into the liquid alloy, and on pouring of mould are transferred to the casting, especially when the filtering system is not sufficiently effective. The specific nature of the melting process of nickel and cobalt alloys, carried out in vacuum induction furnaces,excludes the possibility of alloy refining and slag removal from the melt surface. Therefore, to improve the quality of castings (parts of aircraft engines), it is so important to evaluate the quality of ingots before charging them into the crucible of an induction furnace. It has been proved that one of the methods for rapid quality evaluation is an ATD analysis of the sample solidification process, where samples are taken from different areas of the master heat ingot. The evaluation is based on a set of parameters plotted on the graph of the dT/dt derivative curve during the last stage of the solidification process in a range from TEut to Tsol

The effect of cooling rate on the microstructure of nodular cast iron

Abstract The study gives the results of the investigations concerning an effect of the casting cooling rate ( casting made from nodular iron used as a starting material for austempering to produce ADI) on the morphology of nodular graphite and metallic matrix composition. The features of the microstructure morphology were determined on a LUCIA computer program using castings of 10, 20, 40 and 60 mm diameter. It has been proved that increasing the casting diameter from 10 to 60 mm (i.e. reducing the cooling rate) increases the content of graphite from 10 to 12% and an average area of the precipitations from about 150 to 440 µm 2 , while it reduces the number of the graphite precipitations in 1 mm 2 from about 700 to 260, the mean value of the shape factor from 0,96 to 0,84, and pearlite content in the matrix from about 96% to 84%. The chemical composition seems to have no significant effect, the only exception being Mo whose presence increases in a visible way pearlite content in the matrix at each cooling rate. The obtained results, and specifically the distribution of the frequencies of occurrence of the examined morphological features of graphite, confirm the vast possibilities that the LUCIA computer program of image analysis offers in evaluation of the effect of technological parameters on cast iron microstructure

Optimising stock management in foundries to keep the economic size of orders

Abstract Skillful stock management is one of the main conditions to raise the production output of an enterprise, foundry shop included. This article outlines modern methods of stock management using the generally available Excel calculation sheet to estimate the economic order quantity and minimum stock level required for selected auxiliary materials used in foundry production

ATD and DSC analyses of nickel superalloys

Abstract The study presents the results of investigations of phase transformations that take place during melting and solidification of nickel superalloys, like RENE 77, IN7 13C, MAR 247 and IN 100. Examinations were carried out by the ATD method of thermal analysis and DSC scanning calorimetry. It has been concluded that ATD offers wider possibilities for interpretation of the solidification process at its first stage, when from the liquid state the primary phases of a low heat of solidification are precipitating. The calorimetric method is more useful in the investigation of solid state phase transformations. The obtained values of the solidification parameters (T lik and T sol ) are comparable for both methods, especially as regards alloys solidification. An undeniable advantage of the DSC method is the possibility to measure the value of the heat (enthalpy) of phase transformations, especially during melting of alloys