Abstract: Thermal simulation test, TEM(Transmission Electron Microscope) and nanobeam EDS techniques were used to investigate the dissolving and precipitation behavior in Nb-bearing mciroalloyed steel. The experimental results indicate that: there are two families of precipitates in the as forged samples. The larger precipitates of Nb(C,N) disappear after being held for 2h at 1300°C,while the inclusions of MnS formed from the solidification even remain for 48h held at that temperature. After 30% of predeformtion at 850°C and 900°C, the strain-induced precipitation occurs, that is, the other tiny precipitates. Compared with the samples relaxed at 850°C, the ones that are held at 900°C show larger particles by same holding time but demonstrate the same size when the relaxation time reaches 1000s.
Abstract: The shape, size and packing structure of the hydration products in the plain and fly ash (FA) cement pastes were conducted by the atomic force microscope (AFM). The water-binder ratio was 0.35, two cement pastes was plain cement as control and FA replacing 30% cement by mass, and the curing ages were adopted the 7 days and 90 days respectively. The results show that there are many round particles about 80nm. However, the size of the round particles has been tended to become smaller with the curing time increase. But the packing structure became tight because of the rearranged particle with the curing time increase. Moreover, fly ash would affect markedly the shape, size and packing structure of hydration products. The results indicate that C-S-H clusters in FA cement paste appear the flat shape and looser packing structure due to its low calcium and silicate ratio.
Abstract: The numerical simulation that projectiles, which are different length-diameter ratio, different cone angle, penetratethe same steel target is executed with ANSYS/LS-DYNA. The environmental characteristics are summarized. It provides a reference for the instrument on projectiles.
Abstract: The aim of this paper is to propose a microstructure modeling for prediction of thermal conductivity of plain weave C/SiC fibre bundles considering manufacturing flaws. Utilized photomicrographs taken by scanning electron microscope (SEM), an accurate representative volume element (RVE) model for carbon fiber bundles is established. Based on the steady-analysis method, the axial and transverse thermal conductivity of the carbon fibre bundles are calculated as 40.32Wm-1K-1 and 11.33 Wm-1K-1, respectively. The manufacturing flaws have different effects on thermal conductivity, the study shows that class A porosity has a significant effect on thermal conductivity, which leads to the thermal conductivity on the axial direction decrease by 13.31% and transverse direction decrease by 20.56% compared with no flaws RVE. While class B porosity has little influence on the k-value. The change law of axial and transverse thermal conductivity along with porosity volume is also observed: as porosity volume fraction is increasing, the thermal conductivity of fibre bundles shows significant linear decrease.
Abstract: Hot rolled 350MPa Grade structural hot dip galvanized steel sheets was used to study the effect of annealing process and cold reduction ratio on the microstructures and mechanical properties. The results showed that the experimental steel was recrystallize finished after cold rolling follow different cold reduction ratio and Salt-bath annealing (annealing temperature 750°C and soaking time 60s) under experimental condition. When the cold reduction ratio was increased, annealing temperature was above 720°C, the yield strength and tension strength had no significant change. The annealing temperature was 750°C,the elongation had no significant change . when the cold reduction ratio was increased,the plastic strain ratio value reduced, and the strain hardening exponent value was gradually increase. In the end, that suggested the optimal annealing temperature is 750°C,and cold reduction ratio is 55% to 65%, consequently that obtained good match of mechanical properties and punching property.
Abstract: The corrosion behavior of 304L and 316L stainless steel have been investigated in 55 °C,85% food grade phosphoric acid solution by weight loss method and dynamic potential scan , the surface morphology was observed by scanning electron microscopy(SEM). The results showed that the number of pits in 304L was much more than that in 316L. The contents of Cr inside pits were greater than that in the smooth surface in the two stainless steels, indicating the Cr-poor are prone to corrosion. All the samples exhibited stable passive behavior which can be seen from the potentiodynamic polarization curves, 316L corrosion potential (-0.201V) was higher than that of 304L the corrosion potential (-0.357V), and under the same circumstance, 316L stainless steel was more corrosion-resistant than 304L stainless steel.
Abstract: The influence of radial and axial boundary effect on penetration effect are calculated, numerical simulation are executed to compute the kinetic projectile against deep hard target by finite element code, the boundary effects were achieved for different velocity range. Result shows that the minimal Dt/Dp (diameter ratio of target to projectile) for impact velocity 600m/s is 17.5, while the minimal Dt/Dp for impact velocity 900m/s is 20. Furthermore, the depth of equivalent target to substitute semi-infinite target is twice of penetration depth limit for impact velocity 300m/s, and 1.6 times respectively, for impact velocity 600m/s, 900m/s.
Abstract: Based on background, taking the engineering construction material information management system to replace the traditional artificial management mode in recent years has caused extensive concerns in the construction enterprises. Then, this paper used .NET technology to implement the construction material information management system.
Abstract: Plasma cladding multi-lap joint alloying was attained on low carbon steel with self-designed Fe-Cr-C alloy powder by plasma cladding equipment. The lap-joint proportion is 50%. Microstructure and performance of lap-joint had been analyzed and detected, rosette crystal grain are found in lap-joint area, The structure in this area are more fine and compact, The hardness has been increased.