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[en] Based on the time–temperature parameter method, a modified von Mises stress is proposed to calculate the multiaxial creep damage at high temperature. By employing the strain-based multiaxial fatigue damage models, the modified von Mises stress is used to predict the creep–fatigue life under variable amplitude multiaxial loading at high temperature. The experimental data of GH4169 superalloy and 304 stainless steel conducted under both constant and variable amplitude loadings at high temperature are used to verify the proposed method, and a good agreement is obtained with the experimental data.
[en] A series of laser decontamination tests by a second harmonic generation of a Q-switched Nd:YAG laser with 532 nm, 450 mJ/pulse and 5 ns pulse width was employed to assess the decontamination performances for metal surfaces contaminated with the Co2+, Cs+, Eu3+ ions. The test results investigated by EPMA are presented in this paper
[en] The effect of specimen size on the elastic-plastic fracture toughness behavior of Type 304 stainless steel was characterized by the multiple-specimen J-R curve technique at 4270C. Fracture tests were performed on five compact specimen sizes: 2.5T (thickness = 63.5 mm), 2.5T (thickness = 14.7 mm), 1T (thickness = 25.4 mm), 1T (thickness = 14.7 mm), and 0.577 (thickness = 14.7 mm). In comparison with the 63.5-mm thick 2.5T specimen results, the smaller specimens exhibited higher J/sub Ic values and lower R-curve slopes (dJ/da). However, the differences in J/sub Ic/ and dJ/da were not statistically significant for the 2.5T and 1T specimens, which suggests that size effects for 1T and larger specimens are relatively small or nonexistant. On the other hand, there was a statistical difference between the 0.577T and 2.5T J/sub Ic/ values
[en] Femtosecond laser surface processing (FLSP) is a technique that can be used to modify surfaces imparting many desirable properties, such as an improved wettability, heat transfer, and drag reduction. The morphology of the FLSP surface along with surface chemistry is critical factors that strongly influences the wetting behavior of surfaces produced. Reproducing the FLSP original surface over a large area in an economic manner is a challenge. In this paper, imprinting the FLSP surface on oxygen-free copper is investigated. Based on the topology of an FLSP titanium surface, a model has been established to investigate the topology of the mounds, which is defined by the roughness and period between the self-organized structures. This topology affects the imprint quality indicated by the plastic deformation in the blank and is defined as the target material specimen. Both oxygen-free copper and stainless steel 304 were used as blank target material in this study and represent both soft and hard material specimens. The stress–displacement relationship was used to determine the sensitivity of imprint parameters. The imprint model was verified by comparing an equivalent imprint model with nanoindentation experimental results. The model results showed that the die’s morphology, in particular the die roughness-to-period ratio (referring to the peak-to-valley height and the peak-to-peak distance), had greater influence than the blank material itself.
[en] The Radiation Induced Boiling Enhancement phenomena (RIBE) were confirmed using the SUS304 foil. The SUS304 with plasma oxidized surface shows higher CHF, i.e., about 20% improvement. While, the natural and mixed gas oxidized surface does not show the boiling enhancement. The RIBE has been highly related to the surface conditions. (authors)
[en] The deep drawing formability of a material is established as a function of standard indexes, as strength coefficient and anisotropy coefficient. But these indexes are determined in different conditions to those that take place in the forming process. The simulative assays do not separate the actions due to the different variables that work in the process, as for example, the rolling direction. In the present work a test that uses a wedge shape die is considered in order to obtain the strength and anisotropy coefficients as a function of rolling direction. This way, the assays are carried out under a tensile-biaxial compression stress state similar to that one taking place in the flange zone in deep drawing. The experimented material is a deep drawing quality stainless steel AISI 304. The influence of initial strengthened states, rolling and uniaxial tensile on the steel behaviour are also studied. The results permits the authors establish the validity of the assay from the point of view of the strains produced in the sheet. The initial strain has a higher effect on the material than that one obtained from the tensile-biaxial of the state than the tensile-biaxial compression causes. The anisotropy coefficient changes with the strain for the sheet rolling direction. (Author).
[en] This paper dealt with the corrosion properties of hot-dip aluminized steel and 304 type stainless steel in various corrosion environments. Pitting and crevice corrosion rates of hot-dip aluminized steel were larger than those of 304 type stainless steel, but corrosion mode of the former was general corrosion and its mode of the latter was localized corrosion. By immersion test in 3.5% NaCl solution, also, corrosion rate of hot-dip aluminized steel was faster than that of 304 type stainless steel. In anodic polarization test, corrosion potential of 304 stainless steel was noble than that of hot-dip aluminized steel and showed better passivation behavior