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With the development of production and technology, the devices of oil refining, chemical, fertilizer and others are progressing to the direction of high parameters (high pressure, high temperature). Pressure vessels must be open, which will made the stress concentration problems more serious, and traditional design methods derived from empirically formula fails to meet the actual demand. In this paper, a theoretical result is calculated with a simplified model of the opening holes in cylindrical shell, verified by a group of solutions got by the ANSYS simulation. And it turns out that the result is rather satisfactory.

In order to illustrate the mechanism of supporting, maintain the safety and keep the stable of underground projects, it is of great significance to study the transverse effect of bolted discontinuous rock mass. With a 3D model and corresponding physical simulation, analyzing the testing results of the bolt stress, rock stress and displacement discovers some new findings. Besides its reinforcing effect to the rock mass, the bolt has a negative effect on the discontinuous rock mass by its so-called ‘railway effect’ under shear loading. The finding of this bolt function will help to further understand of bolting mechanism and it is very important to raise the safety of bolt supporting design. Furthermore the effect grade is a positive correlativity with the bolt diameter, and the shear displacement is one of its necessary conditions.

Terzaghi equation is widely used in practice to determine Ultimate Bearing Capacity (UBC). Recent research indicates that exact solution of UBC could be got with the slip line method if the soil is ideal elastic-plastic material. In this paper, dimensionless UBC is gained using ABC software based on the slip line method and is compared with that by Terzagh equation with based on empirical formula. It shows that error of UBC is caused by empirical formula. However, the accuracy of UBC relates to safety and economy of the engineering. Given empirical formulas have a wide application in practice, the scope of application of the four classic empirical formulas is discussed in different range of allowable error. The applicable scope of the four classic empirical formulas within the margin of error is discussed and the results can facilitate the application of classic empirical formulas in practice.

ZnS0.59Se0.41 alloy nanowires were prepared on gold-coated Si substrates by the thermalevaporation of a mixture of ZnSe and ZnS powders. Field-effect transistors (FETs) constructed fromthe ZnS0.59Se0.41 NWs verified their p-type nature with a hole concentration of 3.1×1018 cm-3.Inaddition,the photoresponse indicates their potential for photoelectric applications.

The effects of phosphorus and boron addition on the as-cast microstructure and homogenization parameters of Inconel 718 were studied. The results indicate that the addition of phosphorus and boron promotes the formation of blocky Laves phase. Due to the strong segregation behavior of boron in the final residual liquid, a low melting B-bearing phase enriched in Nb, Mo and Cr is observed. According to the differential scanning calorimeter results and electron probe micro-analysis characterization, the solidification sequence of Inconel 718 with phosphorus and boron addition in best combination is determined as L → L +γ → L +γ+ MC → L +γ+MC+Laves → γ+MC+Laves+B-bearing phase. Accordingly, the homogenization temperature is recommended to be adjusted at least 40°C lower than that of standard Inconel 718 due to the existence of low melting B-bearing phase.

Based on numerical simulation of computing Software ANSYS, the curve of arching coefficient variation of pressure arch due to actual mining was analyzed aiming to a special mining face, the law of stress transfer and change in surrounding rock was discussed, and the evolving features and characteristics of pressure arch was obtained. The analysis and discussion show the following facts: Arch body will become thicker and stress in the arch body increases with working face’s driving distance increasing; the morphology of pressure arch transits from ellipsoid with long axis in the vertical direction to ellipsoid with long axis in the horizontal direction along the trend of working face; along the tendency of working face, the morphology of pressure arch is a ellipsoid with long axis in the vertical direction.

One of the most popular pre-reinforcement structures in the construction of tunnels through weak grounds would be the pipe roof reinforcement. This composite structure consists on installing, prior to the excavation of a length of tunnel, a series of pipes, either parallel to the tunnel axis or at a certain angle with it. By injecting grout through the pipes, the ground in between the pipes is stiffened and the pipes are connected, creating a kind of ‘umbrella’ above the area to be excavated. In this paper, by modifying the upper bound solution for tunnel face stability, the three-dimensional model for expressing the tunnel face stability with pipe roof reinforcement was established. For a typical example, the solutions computed by the proposed approach were compared with the results given by wedge model, trapezoid wedge model and centrifugal-model test to verify the reasonability of the method. It is shown that the calculation results of limit analysis are in close agreement with test results.

In the present work, low carbon low alloy submicro-steel sheet has been developed successfully by severe warm-rolling (SWR) at 500 °C through a single pass. The result shows submicro-structure can be fabricated by severe rolling. The formation of the submicro-structure is attributed to the grain refinement mechanism induced by the severe plastic deformation (SPD). The refinement involves the cutting and subdividing of the original micro-crystals into ultrafine grains by dense dislocation arrays. To a certain extent, dynamic recrystallization in ferrite during SWR also seems to contribute to the formation of the submicro-structure. The thermal stability of the submicro-steel was investigated by annealing the steel at different temperatures. The investigation indicated that the submicro-steel can be subjected to annealing at 550°C without apparent grain growth. The unusually high thermal stability can be attributed to the pining effect of numerous uniformly distributed nano-precipitates in the steel. The sizes of the nano-precipitates belong to two different orders. The average diameter of the large precipitates is about 30 nm and the smaller one less than 10 nm.

Nanostructured layers were fabricated on the surface of 0.4C-1.0Cr and 1.0C-1.5Cr low alloy steels by using an ultrasonic particulate peening (USPP) technique. The microstructures and mechanical properties of the nanocrystallized layers were characterized by means of transmission electron microscopy, and nano-indentation test. Results showed that the average grain size in the surface nanocrystallized layer of 0.4C-1.0Cr and 1.0C-1.5Cr low alloy steel was about 5nm and 10nm, respectively. The nano-indentation hardnesses of the surface nanocrystallized layer were enhanced significantly and reach upwards of 8.0 GPa and 12.5 GPa, respectively.

It has economical and social value to build energy-saving architectures. Foamed concrete is commonly used as non-load bearing structure to save energy of buildings. With reinforcement of fiber foamed concrete can be used as load bearing structure to build architectures. The load bearing structure of fiber reinforced foamed has ability of self thermal insulation to get the aim of energy-saving. In the paper the excellence and disadvantage of foamed concrete is summarized. Methods are given to build the energy-saving architecture with self thermal insulation structure of fiber reinforced foamed concrete in new formwork. The building technology will be applied in new countryside construction in China.

Segregation behavior of a φ406 mm Alloy 718 ingot was investigated and two-stage homogenization treatment was employed to relieve the micro-segregation between dendrite structures. In the first stage homogenization, the Laves phase elimination percentage was expressed dependence of two parameters (time and temperature). In order to characterize the effects of second stage homogenization, a 900 /1 h treatment was conducted after homogenization, which could form δ-phase (Nb-riched) to trace the diffusion of Nb. It was found that average composition of δ-phase area, quantity of δ-phase precipitation and size of δ-phase precipitation would change with the proceeding of homogenization. As a result, homogenous structure can be achieved by means of a two-stage homogenization treatment (1140 /60 h + 1190 /30 h).

Alloy 718 has a very long history, it is still used extensively, which accounts for more than 50% of commercial superalloy productions in the world. The reason is that Alloy 718 exhibits good strength, excellent weldability and lastly, but most importantly, reasonable cost. Recently, confocal scanning laser microscope (CSLM) offers a convenient way for conducting a real-time and continuous in-situ observation of phase transformations at high temperatures. Several studies using CSLM have been reported for low carbon steel, stainless steel and metallic glass materials. The aim of this paper is to study the solidification behavior of Alloy 718 using confocal scanning laser microscope. In addition to the in-situ observation of solidification at different cooling rates, the analysis of microstructure evolution was conducted by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the cooling rate has a great impact on the solidification behavior of Alloy 718. Variation of secondary dendrite arm spacing, morphology change in MC carbide, and Laves phase after solidification at different cooling rates are studied in details. Introduction Alloy 718 is an age-hardenable wrought superalloy used for elevated temperature gas-turbine applications, which is famous for its excellent balance of properties and reasonable cost, accounting for more than 50% of commercial superalloy productions in the world [1]. With the development of land-based power generation and aircraft propulsion, scaling-up of components has become the necessity. In response to market demands the size of Alloy 718 ingot produced by VIM-ESR-VAR triple melting has increased markedly over the past 10 years [2-7]. However, the solutes segregation problem, mainly niobium segregation, is a big issue for producing large size Alloy 718 ingots. Particularly, some macrosegregations such as freckles and white spots formed during the solidification process may lead to failure of entire ingot. Therefore the indepth studies of solidification behavior of Alloy 718 are still needed.