Advanced Materials Research Vols. 146-147

Abstract: For developing the environmentally protective civil textile composites with better impact behaviors, the impact test was made with flax/polypropylene weft knitting composites samples. The mechanisms of fiber reinforcing and fracture were discussed through examining the fracture photographs. This research shows that the samples have better impact behaviors when the volume fraction of flax fiber is about 50%，the amount of layers is 8, and the sinker depth of the flax/pp knitted perform is 9.

Abstract: In order to investigate material behavior at the stage of early fatigue damage and critical fatigue fracture, a new nondestructive testing called metal magnetic memory (MMM) technology, has been introduced in this paper. The fatigue experiments are carried out on the PQ1-6 rotary bending fatigue machine. The MMM fatigue characteristics are presented and analyzed. It has been found that Hp(x) is increasing up to the peak value while the fatigue crack is initiating and growing. After that peak, Hp(x) decreases gradually with the fatigue crack deepening and stress releasing. The gradual increasing Hp(x) is the sign of the early fatigue damage and the Hp(x) peak predicts the critical fracture state. The validity of MMM results has been certified by microscopic metallographic examination. Furthermore, the MMM fatigue behavior is deduced theoretically based on the dislocation mechanics and fracture mechanics.

Abstract: In this paper, ultrasonic materials testing researches are reviewed. The latest progress of ultrasonic testing technology is introduced, including water-squirting ultrasonic C-scan testing, laser ultrasound, ultrasonic feature scan imaging, signal processing and pattern recognition technology in the application of ultrasonic testing.

Abstract: Based on the global environmental deterioration, the greenhouse effect and a series of other problems, the necessity for the development on new ironmaking technology of oxygen blast furnace and gas-recycle in China was discussed. The new technology use coal and oxygen as the main raw materials. The development situation of new technology and its technical advantages over the conventional ones were introduced detailedly. The development situation of related technology abroad was described. The application prospect of this new technology was analyzed from the perspective of energy consumption and CO2 emission. Using the new ironmaking technology of oxygen blast furnace and gas-recycle, It bound to increase steel plant’s overall technological level in china, enhance industry competition and the effect of energy saving as well as emission reduction, promote low-carbon economy development.

Abstract: A special fixture, which can control the ratio(λ) of normal stress/shear stress, was used to study the effect of normal stress on the shear banding behaviors in a Zr-based bulk metallic glasses in the present paper. The experimental results demonstrated that the plastic displacement increased with increasing of λ. Observations of shear bands pattern on the sample surfaces indicated that normal stress have significant impact on the inclined angle, numerical density and length of shear bands. In addition, normal stress is the major factor of inducing multiple shear bands with intersecting, branching and slipping. Based on the observations, the mechanism of plasticity enhancement due to the increasing of normal stress was explored.

Abstract: A simple method for measuring the refraction indices of small hexagonal crystals is studied. The method is based on Brewster angle law. The refractive indices are confirmed by measuring the Brewster angle on two different surfaces. As an example, the measured refractive indices for hexagonal zeolite crystals are ne=1.488 and no=1.327, respectively, which are necessary for further investigations on the nonlinear properties of these zeolite crystal, such as second harmonic generation (SHG) effect. This method avoids the damage of the sample, and is simple and quick, which is suitable for the measurements of small birefringent crystals.

Abstract: Magnesium Alloys are of low density, high specific strength and high strength, leading to much application prospect in industry and civilian use. However, the alloys are restrictedly used because of easy corrosion. In this paper, The Organic coatings on Magnesium Alloys are made. The electrochemical properties of organic coatings are researched by scanning electron microscope (SEM), stereoscopic microscope and electric-chemistry Work station. The research results show that the curves of open-circuit current to time and Tafel polarization shuffle more for the Pu and ER/PU coatings than for base alloy. With addition of the coating, the magnesium alloy has much low corrosion current density (icorr) and high polarization resistance (Rp), and then its Anti-corrosion Property is evidently improved.

Abstract: Fatigue properties of TRIP-aided annealed martensitic steels with chemical composition of 0.2%C, 1.5%Si, 1.5%Mn, 0-1.0%Cr, 0-0.2%Mo, 0-0.05%Nb, 0-18ppmB was examined for application of automotive diesel engine common rail. The steels achieved extremely higher notch fatigue limits and lower notch-sensitivity than the conventional structural steels, especially in steel with boron or without chromium and molybdenum. This was associated with (i) the TRIP effect of a large amount of stable retained austenite and (ii) strain-induced transformed hard martensite which suppressed the crack initiation and growth due to plastic relaxation.

Abstract: Ramie fiber and polypropylene were used as raw materials,ramie fiber/polypropylene composites were prepared by compression molding process,the effects of treating the ramie fiber with silane coupling agent and compatibilizing the composite with maleic anhydride gafted polypropylene(MAPP) on the structure, melting and mechanical properties of the composites were studied，the effects of immersion time in water on the mechanical properties of the composites were also investigated.The results show that,both the modification with coupling agent and by means of compatibilizing agent can strengthen the interfacial bonding between the fiber and matrix in the composite,and also improve its thermal stability.All the modified composites have greater strengths and moduli than the unmodified ones when immersed in water for any periods,especially the impact strength of the MAPP compatibilized composite not only increases with immersion time in water dramatically,but also is improved from that of the unmodified one by 104.84%,239.40%,294.48% and 320.01% respectively when immersed in water for 0,7,14 and 21d.

Abstract: The experimental results on high nitrogen steels refining with high-pressure and bottom-blowing nitrogen were analyzed by the theories of thermodynamics and kinetics in high nitrogen steels smelting. It was shown that nitrogen content in steel increases with the increase of the following factors, that is, pressure, alloying elements (Cr and Mn), bottom-blowing time and bottom-blowing flow. While the nitrogen content in steel decreases with the temperature increase, but it is not obvious. The nitrogen content in steel can also increase with the surface active elements (O and S) decreasing.