Design and analysis of the radiator structure for space power systems

The design, analysis, fabrication, and development of the 5-kWe radiator structure are shown. Thermal performance, meteoroid protection, structural capability during launch, development testing and space operation, material evaluation, and the configuration selection are described. The fin-tube development program depends on the relative values of the thermal coefficients of expansion. The initial selection of aluminum fins and Type 316 stainless-steel tubes was based on previous experience; however, the large differential in their expansion rates showed that an alternate, more compatible, combination was needed. Copper, stainless-steel-clad copper, boron-impregnated aluminum, and an independent radiator with a titanium structure were all considered as alternate materials. The final selection was Lockalloy fins with Type 304 stainless-steel D tubes

Metallurgy: A compilation

A technology utilization program is presented for the dissemination of information on technological developments which have potential utility outside the aerospace and nuclear communities. Discussion is restricted to the effects of hydrogen on a variety of metal alloys, and the mechanical properties of some recently developed alloys. Hydrogen at both low and high pressure is shown to have adverse effects on alloys such as ultrahigh-strength steels, irradiated steels, columbium, inconel alloys, titanium alloys, and certain stainless steels. The mechanical and physical properties of a wide range of alloys, their performance at elevated temperatures, and some of the processes involved in their development are also considered

Fusion materials semiannual progress report for the period ending March 31, 1995

This is the eighteenth in a series of semiannual technical progress reports on fusion materials. This report combines research and development activities which were previously reported separately in the following progress reports: {sm_bullet} Alloy Development for Irradiation Performance. {sm_bullet} Damage Analysis and Fundamental Studies. {sm_bullet} Special Purpose Materials. These activities are concerned principally with the effects of the neutronic and chemical environment on the properties and performance of reactor materials; together they form one element of the overall materials programs being conducted in support of the Magnetic Fusion Energy Program of the US Department of Energy. The other major element of the program is concerned with the interactions between reactor materials and the plasma and is reported separately. The Fusion Materials Program is a national effort involving several national laboratories, universities, and industries. The purpose of this series of reports is to provide a working technical record for the use of the program participants, and to provide a means of communicating the efforts of materials scientists to the rest of the fusion community, both nationally and worldwide. This report has been compiled and edited under the guidance of A.F. Rowcliffe by Gabrielle Burn, Oak Ridge National Laboratory. Their efforts, and the efforts of the many persons who made technical contributions, are gratefully acknowledged

Fracture Mechanics and Fatigue Design in Metallic Materials

The accumulation of damage and the development of fatigue cracks under the influence of loads is a common phenomenon that occurs in metals. To slow down crack growth and ensure an adequate level of safety and the optimal durability of structural elements, experimental tests and simulations are required to determine the influence of various factors. Such factors include, among others, the impact of microstructures, voids, notches, the environment, etc. Research carried out in this field and the results obtained are necessary to guide development toward the receipt of new and advanced materials that meet the requirements of the designers. This Special Issue aims to provide the data, models and tools necessary to provide structural integrity and perform lifetime prediction based on the stress (strain) state and, finally, the increase in fatigue cracks in the material

Evaluation of beryllium for space shuttle components

Application of beryllium to specific full-scale space shuttle structural components and assemblies was studied. Material evaluations were conducted to check the mechanical properties of as-received material to gain design information on characteristics needed for the material in the space shuttle environment, and to obtain data needed for evaluating component and panel tests. Four beryllium structural assemblies were analyzed and designed. Selected components of these assemblies, representing areas of critical loading or design/process uncertainty, were designed and tested, and two panel assemblies were fabricated. Trends in cost and weight factors were determined by progressive estimation at key points of preliminary design, final design, and fabrication to aid in a cost/weight evaluation of the use of beryllium

Mechanical and electrochemical properties of inconel alloy 617 after refurbishment through heat treatment

The transition piece in gas turbine is an important component, which joins the combustion chamber to the turbine nozzles. These pieces are made from an alloy that resist high temperature and thermal loading and being considerably expensive. The high operating temperature and thermal fatigue limit the lifetime of such component Consequently, the life extension of the alloy through sound refurbishment process is in demand. The refurbishment of Inconel 617 alloy after 37000 hours of operation in the field is considered through heat treatment process. Tensile and fatigue properties, as well as microstructures and elemental composition of the alloy before and after the heat treatment process are investigated. In addition, the electrochemical response of the heat-treated alloy is investigated through potentiodynamic surface testing. The heat treatment process is carried out at 1175 °C for one and two hours in air free furnace. It is found that the heat treatment of the alloy for one hour partially improves the cavitations at grain boundaries and the fatigue response of the workpiece partially improves. Further, dimples at grain boundary facets was noticed after the heat treatment which is an evident of ductility of the workpieces. Moreover, the corrosion resistance improves considerably for the workpieces subjected to one-hour heat treatment Consequently heat treatment of the Inconel 617 alloy after long term of operation improves slightly its properties and partial regaining of the alloy properties thought heat treatment with temperature rang and the duration employed in the present work is visible