In Situ Small Scale Mechanical Characterization of Materials Under Environmental
Sanders, Matthew Wayne
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This research investigates the mechanical properties and performance of structural materials at a small volume scale. In situ observation was made possible through the Small Punch Test (SPT) method as well as tribological testing. Experimentally, aluminum and titanium alloys were examined using those two techniques. Analysis of their behavior in comparison with their published mechanical properties made it possible to establish connections between test parameters and conventional uniaxial tensile test properties. Connections were generated between SPT parameters and tribological performance. This research used experimental approaches to develop an understanding of the material behaviors during small punch testing and apply them to hydrogen embrittlement. The SPT for such alloys were highly repeatable and specimen surface roughness did not have visible impacts on repeatability. Analysis indicated that there is a link between the SPT and conventional mechanical properties. The relationship between the applied force and the slop of the FvE curve is associated with the tensile strength and elastic modulus. It was found that the SPT can be used to qualitatively gage wear resistance. The SPT was used to analyze hydrogen effects, and no significant effects were seen on 3003-H14 and 2618-T61 aluminum alloys; however, effects were seen on a Ti-6Al-4V alloy. It was also found that hydrogen showed no visible effects on friction and wear. The SPT can now be applied more accurately to the testing of aluminum alloys and new doors for the potential of small punch testing in the application of hydrogen embrittlement and surface characterization have been opened. This thesis consists of six chapters. The first chapter serves as an introduction to the background necessary to understand the rational and motivation for the present research. The second chapter will go into detail about the motivation and the objects of the research while the third chapter will explain the experimental procedures that were conducted to fulfill these objectives. The fourth chapter will present the results of these experiments, and they will be discussed in the fifth chapter. Finally, in the sixth chapter, conclusions will be stated and future work will be discussed.