Advanced Materials Research Vols. 284-286

Abstract: By taking cold conventional rolling technique on austenitic high manganese steel specimens, their hardness increase. The microstructure is studied to analyze the reason why cold conventional rolling technique can create work hardening and improve wear-resisting performance of austenitic high manganese steel with the increase of deformation. The research will make great significance to theory and practice.

Abstract: Deadlock prevention, deadlock detection and deadlock avoidance strategies are used to solve the deadlock problems of flexible manufacturing systems (FMSs). The conventional prevention policies were always attempt to prevent the system entering the deadlocked situation by using a few control places. On can know that one prohibits the deadlocked markings, some dead markings will be sacrificed. Therefore, the reachability states will become less than the initial net. However, our goal is to preserve all the reachability states of the initial net. Under our control policy, the deadlocks or deadlock zone will be channelized to live markings such that all the dead markings in reachability states will be conserved. Finally, an example is performed and can obtain the maximal permissiveness of a Petri net model. The other examples are all getting the same result. To our knowledge, this is the first work that employs the channelized method to prevent the deadlock problem for FMSs.

Abstract: The effects of hot compression deformation (300°C/0.1s-1) and annealing on the microstructural evolution of ZK60+0.8Zn (ZK60M) alloys were investigated in the present works. Lots of sub-structures were studded in the shear bands under the deformed conditions, and after annealing, the sub-structures in the shear bands occurred static recrystallization following by the growth of recrystallized grains. With the increase of annealing temperature, amounts of twins decrease while static recrystallization (SRX) grains increase while dislocations rearrange forming sub-grains ultimately induced static recrystallization. And that, the micro structural evolution and grain boundary distribution of the specimen as-deformed and as-annealed at different temperatures were analyzed by electron back scatter diffraction (EBSD) data.

Abstract: In this paper, the influence of B on the existence form and the phase composition of Zr in alloy were studied. And the influence mechanism of B on Zr in alloy was analyzed. The results show that the addition of B makes part of Zr become precipitation present in grains and grain boundaries as the small plate sheet of second phase from solution. It reduced the lattice distortion, improved the ordering of Al matrix and the conductivity of the alloy.

Abstract: ASME SA-213 T91 tubes and SA-335 P91 pipes were widely used in combined-cycle steam systems due to their greater increased temperature strength and creep behavior. In this paper, a practical and selective spectrophotometric method for the determination of molybdenum in ASME SA-213 T91 tube and SA-335 P91 pipe samples has been presented. This method was based on the chromogenic reaction between molybdenum(V) and sodium thiocyanate. Employing stannous chloride as a reductant, molybdenum(VI) was reduced to molybdenum(V) at the room temperature. The obtained molybdenum(V) formed an orange-red-colored (1:5) ligand complex with thiocyanate. The absorbance of the complex was measured at 470nm, and the molar extinction coefficient is 1.75´10⁴L·mol^-1·cm^-1. Under the optimum reaction conditions the absorption value was proportional to the concentration of molybdenum in the range of 0.40~1.21%, and the relative standard deviation was less than 3.0%. The proposed method was free from the interference from a large number of analytical important elements and has been applied satisfactorily to the determination of molybdenum in grade T91 tube and P91 pipe samples with the improved accuracy and precision.

Abstract: The over-burnt temperature of a new Al-Mg-Si-Cu Aluminum alloy was studied by means of DSC and microstructure analysis, as a result of the homogenization temperature being obtained. A favorable homogenization time was got by the way of the dependence of area fractions of remnant phases on homogenization time being calculated. According to experimentation results, the over-burnt temperature of the new Al-Mg-Si-Cu Aluminum alloy was 570°C, and the way to homogenize the new alloy at 560°C for 24h was excellemt.

Abstract: The new Al-Mg-Si-Cu aluminum alloy has been developed for application in cold and hot extrusion and forging. Its nominal composition is 1.37%Mg、0.85%Si、0.82%Cu、0.11%Cr and 0.15%V. In this paper, The hot deformation behaviors of the new Al-Mg-Si-Cu aluminum alloy were studied by means of compression deformation tests on MMS-200 multifunctional materials simulation machine at strain rates ranged between 0.1~0.5s^-1 and deformation temperature between 350~550°C. The laws of the flow stress dependent both on thedeformation temperature and strain rates were discovered, and then the relationship between the first peak-stress σ_p and strain rates was obtained through one-dimensional linear regression.

Abstract: Anisotropic Nd_13.5Fe_79.5B₇ magnetic powders are obtained by varying the desorption H₂-pressure of the hydrogenation disproportionation desorption recombination (HDDR) process. The magnetic powders with a desorption H₂-pressure of 10 kPa have the magnetic properties of Br =0.61 T and Mr/Ms =0.67, whereas the magnetic powders obtained with a higher and a lower desorption H₂-pressure are isotropic. A lamella crystal is observed in the 10 kPa desorption H₂-pressure products and may be related to the anisotropy in the HDDR-treated powders. It suggests that the desorption H₂-pressure has great effect on the formation of crystal texture in the HDDR Nd-Fe-B powders.

Abstract: The effect of Y addition on the microstructure of AZ61 alloy was investigated by optical microscopy (OM), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The corrosion behavior of AZ61 alloy with Y addition in 3.5 % NaCl solution was studied by static weight loss and polarization curves corrosion tests. The results show that AZ61 alloy with Y addition can refine grain size of the matrix and alter the distribution of the phase β-Mg₁₇Al₁₂ from continuous network morphology transition to small and dispersive distribution along the grain boundary by forming the second phase Al₂Y which has a high melting point. In addition, the addition of Y can decrease the corrosion current density of AZ61 magnesium alloy in 3.5% NaCl solution, thereby improving the corrosion resistance of AZ61 magnesium alloy. Results show that AZ61 magnesium alloy with 1.0% Y has the most refined microstructure and the best corrosion resistance.

Abstract: The zinc alloy samples were prepared under the condition of the vibration and ordinary pressure, 0.4Mpa pressure and 0.7Mpa pressure. The photos of the microstructure morphology were obtained by optical microscopy. The analysis result shows that the crystalline microstructure of solidification by the band edge changes from dendrite-shaped to oval, spherical grains. The internal grains havealso been refined.