The use of polymers in bituminous materials has been gaining popularity over the last decade. Despite their superiority in enhancing the performance of bituminous mixtures, problems have been experienced due to limitations on the applicability of currently available assessment techniques. This thesis is concerned with the mechanical behaviour of polymer modified bitumens and the performance of polymer modified bituminous mixtures. The first part of the thesis presents different pavement distresses and the importance of using polymer modified binders to improve the performance of bituminous mixtures. The second part deals with identification of properties of polymer modified binders and their mixtures by using dynamic mechanical analysis. The third part attempts to develop a novel technique for assessing resistance to permanent deformation of HRA mixtures using a dissipated energy method. Some polymer modified binders are susceptible to storage instability. However, this work has demonstrated that certain empirical tests are unsuitable for assessing the temperature susceptibility and storage stability of polymer modified binders. Viscoelastic behaviour of bituminous materials is better presented by dynamic mechanical analysis. The dynamic mechanical analysis provides a basis for explaining the unsuitability of some empirical tests on polymer modified binders. Determination of dissipated energy during creep testing enables more comprehensive and accurate assessment of the resistance to permanent deformation of Hot Rolled Asphalt (HRA) mixtures. This study reveals that assessment of the resistance to permanent deformation based upon permanent strain rate in the linear region is in good agreement with the dissipated energy method. The end of the linear region, N1, can be accurately determined by the dissipated energy method and provides a confidence that analysis will always be conducted in the linear region. As expected, polymer modified mixtures are superior to the unmodified ones in their resistance to permanent deformation which confirm by the wheeltracking test, but was not evident from the Marshall tests.

The published literature on the strength and structural changes occurring during and after hot working of AI5I316 and 304 austenitic stainless steels are reviewed. Isothermal plane strain compression tests have been carried out with the purpose of determining relationships to describe the kinetics of static recrystallization, the recrystallized grain size, the isothermal grain growth rate and the strength during hot rolling of AISI316 steel. The kinetics of static recrystallization were also studied in samples tested in axisymmetric compression, or hot rolled. The effect on the kinetics of static recrystallization of the strain distribution in samples tested in plane strain compression was analysed. The set of equations determined for 316 steel wasused in a computer model modified from the one developed by Leduc (1980) for simulation of hot rolling loads and microstructural evolution. Partially recrystallized microstructure was generated in a laboratory hot rolling mill and was reasonably simulated by the use of the computer programme. Non-isothermal plane strain compression tests were carried out for direct simulation of laboratory hot rolling results. Comparison between experimental hot rolling and plane strain compression data has shown reasonable levels of agreement in the microstructural simulations undertaken in the present work. The mean plane strain strengths from non-isothermal plane strain compression tests were higher than the ones from hot rolling. This may have been caused by thermal gradients inside the sample being tested.

Hot rolling process is heat input process. The heat energy in hot rolled steel coils can be utilized. At SSAB Strip Product Borlänge when the hot rolled steel coils came out of the hot rolling mill they are at the temperature range of 500°C to 800°C. Heat energy contained by the one hot rolled steel coil is about 1981Kwh whereas the total heat energy for the year 2008 is 230 GWh/year.The potential of heat is too much but the heat dissipation rate is too slow. Different factors on which heat dissipation rate depends are discussed.Three suggestions are proposed to collect the waste heat from hot rolled steel coils.The 2nd proposal in which water basin is suggested would help not only to collect the waste heat but to decrease in the cooling time.

Effect of stress-assisted aging on stress induced martensitic transformation in hot-rolled Ni-rich 50.7at. Ni%-Ti alloy has been investigated. Alloys are aged freely and under 20 MPa, 100 MPa, and 200 MPa stress at 400 o C for 90 minutes. Aging procedure affected both stress-induced and thermally induced transformation behavior. Superelasticity behavior is correlated with the multistep transformation in aged Ni-rich NiTi alloys and the aging stress level is found to be effective. Relative to the free aged alloy, the alloy aged under 20 MPa exhibited a slight and the alloy aged under 100 MPa exhibited a considerable reduction, whereas the alloy aged under 200 MPa exhibited an increase in the critical transformation stress. DSC studies have shown that the transformation is multistep for freely aged and aged under 20 MPa alloys, whereas it is single step and two-step for alloys aged under 100 MPa and 200 MPa, respectively, and this has been attributed to the effect of stress on nucleation and growth rates. As a result of the different response mechanisms to the applied stress upon loading during superelasticity testing, the recovered strain amounts varied considerably depending on the aging conditions and the test temperatures.

The successful use of Nickel-Titanium (Nitinol) in biomedical applications requires an accurate control of its unique mechanical properties. The purpose of this study is to analyze the effects of a wide range of heat treatments on the mechanical behavior of hot-rolled and cold-drawn Nitinol. Results comprise an understanding of the effect of heat treatment temperature and time variation on final material response which is imperative for optimization of material properties. Thirty-three heat treatment variations are tested by combining three durations, 10 minutes, 90 minutes, and 8 hours, with eleven different heat treatment temperatures between 200°C and 440°C. Following heat treatment, the Nitinol samples undergo tensile testing with upper plateau strength, lower plateau strength, ultimate tensile strength, strain to failure, and residual elongation compared for all test groups. Heat treatment "power" is used to describe the efficacy of different combinations of heat treatment temperature and duration. When using hot-rolled Nitinol, results show a low heat treatment power does not create significant precipitation hardening or a significant decrease in martensite transformation stress, resulting in a high upper plateau strength, high residual strain values, and evidence of plastic deformation upon unloading. Moderate power treatments lead to sufficient hardening of the material and a decrease in martensite transformation stress resulting in a pseudoelastic response. Increasing to a high treatment power further decreases the transformation stress and increases the martensite transformation temperature leading to a shape-memory response in hot rolled Nitinol. When using cold-drawn Nitinol, low and moderate heat treatment power levels result in the material exhibiting a pseudoelastic response. Increasing heat treatment power shows the same effects on martensite transformation stress and temperature as seen with the hot-rolled material resulting in a material response transition from pseudoelastic to shape memory.

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.L’objectif de cette étude était, en premier lieu, de mettre en place en Thaïlande un testd’adhésion par traction-écaillage sur une machine de traction classique (test« macroscopique »), de le comparer au test « microscopique » Grenoblois fonctionnant dansla chambre du MEB et de l’utiliser pour évaluer l’adhérence des calamines de process sur desaciers industriels. Deux paramètres ont été étudiés, la vitesse de déformation et la teneur desaciers en silicium. Il apparaît que l’écaillage des calamines au cours du test augmente quandaugmente la vitesse de déformation. Une vitesse de déformation élevée entraîne unedéformation au premier écaillage plus faible, donc une adhérence mesurée plus faible. Ceteffet est lié aux phénomènes de relaxation. On a pu alors montrer que la présence d’oxyde(s)contenant Si, situé(s) à l’interface avec le métal, augmentait l’adhérence. Les étudesd’oxydation dans la vapeur d’eau qui ont aussi été réalisées ont révélé que la présence desilicium réduisait la vitesse d’oxydation. En augmentant la teneur en Si, les couches defayalite et de wüstite s’épaississent ; par contre, les couches externes s’amincissent. Pour lesaciers contenant du cuivre, la vitesse d’oxydation est réduite quand la teneur en Cu estaugmentée. De la même façon, les couches internes sont plus épaisses et on observe uneaugmentation du nombre de précipités de Cu quand la teneur en cet élément augmente. / The purpose of this study was first to develop in Thailand a “macroscopic” adhesion testusing a conventional tensile machine, to compare it to the micro-tensile test used in Grenobleand sitting in the SEM chamber, and to use it for measuring adhesion of scales grown duringprocessing on industrial steels. Parameters affecting the test, i.e. strain rate and Si content ofsteels were investigated. The results showed that spallation of scales during strainingincreased with increasing tensile strain rate. A higher strain rate resulted in lower straininitiating the first spallation and lower mechanical adhesion of scales, which could beexplained by a relaxation effect. Oxide containing Si existed at the steel-scale interface andpromoted adhesion of scales. Oxidation studies were also performed, and the behaviour inwater vapour of steels with different contents of Si and Cu was investigated. Increasing Sicontent tended to decrease oxidation rate. It also resulted in the thickening of the wüstite andfayalite layers which formed by internal oxidation. When Si in steel increased, theintermediate (FeO + Fe3O4) and outermost (Fe2O3 sitting on Fe3O4) layers formed by externaloxidation were thinner. For Cu containing steel, increasing Cu content tended to decrease theoxidation rate. It also decreased the innermost and intermediate layers and resulted in moreCu precipitates along steel-scale interface.

Structure-property quantification of an A36 steel alloy was the focus of this study in order to calibrate and validate a plasticity-damage model. The microstructural parameters included grain size, particle size, particle number density, particle nearest neighbor distances, and percent of ferrite and pearlite. The mechanical property data focused on stress-strain behavior under different applied strain rates (0.001/s, 0.1/s, and 1000/s), different temperatures (293 K and 573 K), and different stress states (compression, tension, and torsion). Notch tension tests were also conducted to validate the plasticity-damage model. Also, failure of an A36 I-beam was examined in cyclic loads, and the crack growth rates were quantified in terms of fatigue striation data. Dynamic strain aging was observed in the stress-strain behavior giving rise to an important point that there exists a critical temperature for such behavior.