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To minimize the production cost and time of the heat treatment of critical application aluminum castings within the automotive industry a combined hot isostatic pressing (HIP)/solution heat treat process is desired. A successfully combined process would produce parts of equal quality to those produced by the individual processes of HIP and subsequent heat treatment with increased efficiency in time and energy. In this study, an experimental combined process was designed and implemented in a production facility. Industrially produced aluminum castings were subjected to the combined process and results were quantified via tensile and fatigue testing and microscopic examination. Comparisons in fatigue and tensile strength were made to raditionally HIPed and heat treated samples, as well as un-HIPed samples in the T6 condition. Results show that castings produced with the combined process show fatigue properties that are equal in magnitude to castings produced with the independent HIP and heat treatment processes. Furthermore, an order of magnitude improvement in the fatigue life in those castings that were produced with the combined process exists compared to the castings that were only heat treated. This study shows no difference in the tensile properties that result from any of the processing routes compared. Also, microstructural comparison of the castings processed show no difference between the process routes other than porosity, which is only evident in the un-HIPed samples. Dendrite cell size and dendritic structure of the samples that were solutionized for the same time is identical. Theoretical examination of the combined process was also completed to quantify the energy consumption of the combined process compared to the independent processes. Thermodynamic calculations revealed that the energy consumed by the combined process for a typically loaded HIP vessel is fifty percent less than the energy required to process the same quantity of castings with the two individual processes. However, it was determined that a critical ratio of the volume occupied in the HIP vessel by castings to the total HIP vessel volume exists that ultimately determines the efficiency of the combined process. This critical ratio was calculated to be approximately fifteen percent. If the volume ratio is less than fifteen percent then the combined process is less energy efficient then conventional processing. These thermodynamic calculations were experimentally verified with power consumption process data in a production facility. In addition, the time required for the combined process of HIP and solution heat treatment was calculated as thirty-percent less than the conventional two-step process. This calculation was verified via the comparison of data compiled from the experimental combined process.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Gordon Bruce Hunter. / M.S.

This thesis documents a PhD research program undertaken at Swinburne University of Technology between the years 2000 and 2004. The research was funded by the Cooperative Research Centre for Cast Metals Manufacturing and was undertaken in collaboration with Nissan Casting Plant Australia Pty Ltd and the Ford Motor Company Australia Limited. This thesis reports on the investigation of the possibility of using an ultrasonic sensing-based, non-destructive testing system to detect gas porosity defects in aluminium die casting parts with rough surfaces. The initial intention was to develop a procedure to obtain ultrasonic signals with the maximum possible amplitude from defects within the rough surface areas of the castings. A further intention was to identify defects with the application of a suitable signal processing technique to the raw ultrasonic signal. The literature review has indicated that ultrasonic techniques have the potential to be used to detect subsurface defects in castings. The possibility of classifying very weak ultrasonic signals obtained from rough surface sections of castings through a neural network approach was also mentioned in the literature. An extensive search of the literature has indicated that ultrasonic sensing techniques have not been successfully used to detect sub-surface defects in aluminium die castings with rough surfaces. Ultrasonic inspection of castings is difficult due to the influence of microstructural variations, surface roughness and the complex shape of castings. The design of the experimental set-up used is also critical in developing a proper inspection procedure. The experimental set-up of an A-scan ultrasonic inspection rig used in the research is described in this thesis. Calibration of the apparatus used in the inspection rig was carried out to ensure the reliability and repeatability of the results. This thesis describes the procedure used to determine a suitable frequency range for the inspection of CA313 aluminium alloy castings and detecting porosity defects while accommodating material variations within the part. The results obtained from ultrasonic immersion testing indicated that focused probes operating at frequencies between 5 MHz and 10 MHz are best suited for the inspection of castings with surface roughness Ra values varying between 50 [micro milli] and 100 [micro milli]. For the purpose of validating the proposed inspection methodology, gas porosity defects were simulated through side-drilled holes in the in-gate section of selected sample castings. Castings with actual porosity defects were also used in this research. One of the conclusions of this research was that it was extremely difficult to detect defects in castings with surface roughness above 125 [micro milli]. Once the ultrasonic signal data was obtained from the sample aluminium die castings with different surface roughness values ranging from 5 [micro milli] to 150 [micro milli] signal analysis was carried out. Signal feature extraction was achieved using Fast Fourier Transforms (FFT), Principal Component Analysis (PCA) and Wavelet Transforms (WT) prior to passing the ultrasonic signals into a neural network for defect classification. MATLAB tools were used for neural network and signal pre-processing analysis. The results indicated that poor classification (less than 75%) was achieved with the WT, PCA and combination of FFT/PCA and WT/PCA pre-processing techniques for rough surface signals. However, the classification of the signals pre-processed with the combination of WT/FFT, FFT/WT and FFT/WT/PCA classifiers provided much better classification of more than 90% for smooth surface signals and 78% to 84% for rough surface signals. The results obtained from ultrasonic testing of castings with both real and simulated defects were validated with X-ray analysis of the sample castings. The results obtained from this research encourage deeper investigation of the detection and characterisation of sub-surface defects in castings at the as-cast stage. Implications for the industrial application of these findings are discussed and directions for further research presented in this thesis.

The aim of this thesis was to perform the classification of defects of emerging in a specific type of steel castings made by company UNEX Foundry, Ltd. and then determine the conditions of their origin. This is mainly discontinuity of casting material. The next step was to propose the corrective measures eliminating creation of these defects.

Cast modular components have been under development for earthquake resistant steel structures. These concepts take advantage of the versatility in geometry afforded with the casting process to create components specifically configured for ductile behavior. Two systems were developed as part of this dissertation research: (1) the Cast Modular Ductile Bracing system (CMDB); (2) the Floating Brace system (FB).The CMDB system makes use of cast components introduced at the ends and the center of the brace to produce a special bracing detail with reliable strength, stiffness and deformation capacity. The system takes advantage of the versatility in geometry offered by the casting process to create configurations that eliminate non-ductile failure modes in favor of stable inelastic deformation capacity. This thesis presents analytical research performed to determine the buckling strength and buckling direction of the bracing element based on the geometries of the cast components. Limiting geometries are determined for the cast components to control the buckling direction. Design formulas for buckling strength are proposed. The Floating Brace system is a new lateral bracing concept developed for steel special concentric braced frames. The concept uses a set of special plate details at the end of the brace to create a stiff, strong and ductile lateral bracing system. The plates are arranged such that some provide direct axial support for high initial stiffness and elimination of fatigue issues for daily service wind loads. The remaining plates are oriented transverse to the brace and thus provide ductile bending response for the rare earthquake event, in which the axial plates become sacrificial. The main bracing member and cast pieces remain elastic or nearly elastic. Thus, following the seismic event, the plates can be replaced. In this thesis, analytical studies using nonlinear finite element analysis are performed to determine the optimum: (a) relative strength of the end connection to the brace; and (b) ratio of strength between axial and transverse plates. Design equations are provided. Prototypes for each concept were developed. Castings were created. Large scale laboratory physical testing was performed as experimental verification (proof of concept) for the two systems.

This thesis is dedicated to analysis of job satisfaction in all races of Beneš a Lát a.s. The aim of this work is the discovery of important factors of job satisfaction and their examination on a statistically significant sample of employees. Prologue of this work is complemented by the establishment of the working hypotheses. Important factors of satisfaction are identified on the basis of the study literature and personal investigation at the place of research. Given the nature of the factors is found assembled interviews and research conducted. According to data obtained is described research sample. Followed by the presentation of the information and interpretation of relevant data. The conclusion deals with the screening of the working hypotheses and design of remedial measures. Work is supplemented by a list of the references and appendices.

"Research and development of magnesium casting alloys depends largely on the metallurgist’s understanding and ability to control the microstructure of the as-cast part. Currently few sources of magnesium solidification information and as-cast microstructures exist. Therefore, the goal of this research is to increase the general knowledge base of magnesium solidification behavior and to characterize the resultant microstructures. Equipment has been developed and constructed to study the solidification behavior of magnesium-aluminum casting alloys via non-equilibrium thermal analysis and continuous torque dendrite coherency measurements. These analyses have been performed on six magnesium-aluminum alloys, including industry dominant alloys such as AM60 and AZ91E, and experimental alloys which show commercial potential such as AXJ530. The resultant microstructures have been characterized for general microstructure trends and the various phases present were analyzed using optical and scanning electron microscopy, as well as energy dispersive x-ray spectroscopy. The measurements were performed using a cooling rate on the order of 1-2°C/s, and results of these analyses show that in general, magnesium-aluminum casting alloys have relatively large solidification ranges, non-dendritic microstructures, and coherency points that are similar to those of aluminum casting alloys. These results should prove useful for research directed towards development of new magnesium alloys that are targeted for specific applications, as well as for optimizing casting procedures for Mg-Al alloys to obtain defect free cast structures."

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography : p. 185-189. / by Robert J. Woodham. / Ph.D.

Thesis (M.Phil.) - University of Queensland, 2006. / Includes bibliography.