Numerical and Experimental Investigations on SGMF of GH3044 Superalloy Tube

According to the GH3044 nickel-based superalloy with high yield strength, a new approach for superalloy tube named Tube Solid Granules Medium Forming (SGMF) was present, and tube SGMF process principle and the mechanical model of solid granules were designed. The superalloy tube SGMF process was investigated numerically by using User subroutine of Abaqus software, the deforming simulations of two groups of tube products were performed separately, and the elongation rate and thickness distributions of the products were analyzed. An experimental system was designed and developed for tube SGMF, typical GH3044 superalloy tubes were deformed, good correlation was observed between the simulation results and experimental data.

Study on Lateral Pressure-Transfer Regularity of Tube SGMF under High Pressure

The mechanical model of Tube Solid Granules Medium Forming (SGMF) is simplified to three pressure-transfer models: uniform pressure model, unequal diameter model and tube SGMF model. Combining the conclusions of the SGMF investigation and the theories of powder mechanics, lateral pressure-transfer regularity of SGMF under high pressure has been investigated and the mathematical formulas of pressure distribution have been obtained. According to the theoretical analysis, the lateral pressure and the depth of solid granules can be expressed by a segmented function. An experimental set-up has been designed and manufactured to evaluate the theoretical results, good correlation has been observed between the theoretical results and the experimental data.

Geochemistry of marine sediments of the Brazilian Northeastern continental shelf

The marine sediment samples collected from the northeastern Brazilian continental shelf, at water depths between 20 and 80 m, consisted mainly of sands with an almost total absence of gravel and granules. Medium, coarse and very coarse sand grains are mostly composed of halimeda, lithothamnium, rodoliths and bioclastic sands with a carbonate content varying between 77 and 96 %. The chemistry in general shows a decreasing content of Ca (86.1 %) >Si (6 %) > Cl (3.6 %) > Sr (0.8 %) > K (0.66 %) > S (0.62 %) > Al (0.6 %) > Na (0.55%) > Mg (0.43 %) > Fe (0.4 %) > P (0.2 %) > Br (0.04 %) in the samples. There was no correlation between CaCO3 and chemical contents and grain size with depth and bio-components. With the exception of Sr of marine origin, all other elements (P, S, Br, Cl, Fe) are of continental origin. The lithothamnium of some offshore samples shows higher CaCO3 content, while Mg and Na are present only in halimedas. Bioclastic sands contain no Br, and silt and clay fractions are rare and characterize samples closer to the coast. These marine bioclastic granulates are of very pure biogenic calcium carbonates and are thus highly to be recommended for economic purposes.