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

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

Exploring the Bimodal Solar System via Sample Return from the Main Asteroid Belt: The Case for Revisiting Ceres

Abstract: Sample return from a main-belt asteroid has not yet been attempted, but appears technologically feasible. While the cost implications are significant, the scientific case for such a mission appears overwhelming. As suggested by the “Grand Tack” model, the structure of the main belt was likely forged during the earliest stages of Solar System evolution in response to migration of the giant planets. Returning samples from the main belt has the potential to test such planet migration models and the related geochemical and isotopic concept of a bimodal Solar System. Isotopic studies demonstrate distinct compositional differences between samples believed to be derived from the outer Solar System (CC or carbonaceous chondrite group) and those that are thought to be derived from the inner Solar System (NC or non-carbonaceous group). These two groups are separated on relevant isotopic variation diagrams by a clear compositional gap. The interface between these two regions appears to be broadly coincident with the present location of the asteroid belt, which contains material derived from both groups. The Hayabusa mission to near-Earth asteroid (NEA) (25143) Itokawa has shown what can be learned from a sample-return mission to an asteroid, even with a very small amount of sample. One scenario for main-belt sample return involves a spacecraft launching a projectile that strikes an object and flying through the debris cloud, which would potentially allow multiple bodies to be sampled if a number of projectiles are used on different asteroids. Another scenario is the more traditional method of landing on an asteroid to obtain the sample. A significant range of main-belt asteroids are available as targets for a sample-return mission and such a mission would represent a first step in mineralogically and isotopically mapping the asteroid belt. We argue that a sample-return mission to the asteroid belt does not necessarily have to return material from both the NC and CC groups to viably test the bimodal Solar System paradigm, as material from the NC group is already abundantly available for study. Instead, there is overwhelming evidence that we have a very incomplete suite of CC-related samples. Based on our analysis, we advocate a dedicated sample-return mission to the dwarf planet (1) Ceres as the best means of further exploring inherent Solar System variation. Ceres is an ice-rich world that may be a displaced trans-Neptunian object. We almost certainly do not have any meteorites that closely resemble material that would be brought back from Ceres. The rich heritage of data acquired by the Dawn mission makes a sample-return mission from Ceres logistically feasible at a realistic cost. No other potential main-belt target is capable of providing as much insight into the early Solar System as Ceres. Such a mission should be given the highest priority by the international scientific community

Quantitative Evaluation of Porosity in Turbine Blades Made of IN713C Superalloy After Hot Isostatic Pressing

The aim of this paper is an assessment of the influence of hot isostatic pressing treatment on porosity of cast samples - turbine blades and vane clusters made of the IN713C superalloy. Two variants of HIP treatments, differing in pressure from each other, have been used

Evaluation of Carbides in Turbine Blade Made of IN713C Superalloy After Hot Isostatic Pressing

The IN713C is nickel-based superalloy, used to produce low pressure turbine blades in a process of investment casting. However, porosity which is formed during the casting, decreases mechanical properties of IN713C. Therefore, to eliminate porosity, a process of hot isostatic pressing was applied. Nonetheless, HIP also least to some changes in the microstructure of tested material. The main aim of this paper is to characterize the morphology of carbides before and after hot isostatic pressing. Microstructural characterization was carried out with the use of a scanning electron microscope equipped with an energy dispersive X-ray spectrometer and an electron backscatter diffraction detector. The size and shape of carbides were evaluated by quantitative metallography methods methods. The results show that the amount, size and heterogeneity of arrangement of the carbides increased after application of HIP treatment

Evaluation of Carbides in Turbine Blade Made of IN713C Superalloy After Hot Isostatic Pressing

The IN713C is nickel-based superalloy, used to produce low pressure turbine blades in a process of investment casting. However, porosity which is formed during the casting, decreases mechanical properties of IN713C. Therefore, to eliminate porosity, a process of hot isostatic pressing was applied. Nonetheless, HIP also least to some changes in the microstructure of tested material. The main aim of this paper is to characterize the morphology of carbides before and after hot isostatic pressing. Microstructural characterization was carried out with the use of a scanning electron microscope equipped with an energy dispersive X-ray spectrometer and an electron backscatter diffraction detector. The size and shape of carbides were evaluated by quantitative metallography methods methods. The results show that the amount, size and heterogeneity of arrangement of the carbides increased after application of HIP treatment