Advanced Materials Research Vols. 129-131

Abstract: The influence of solution annealing on the microstructure and mechanical properties of high nitrogen Fe-Cr-Mn-Mo-N austenitic stainless steels prepared by MIM was investigated. The results show that the solution treatment can improve the microstructure and properties of the stainless steels significantly. The sintered specimens before solution annealing consist of γ-austenite and embrittling intergranular Cr2N precipitates, showing a low mechanical property. After solid solution annealing, the specimens reveal a fully austenitic structure without any intergranular nitrides, whose tensile properties are much higher than those without solution annealing, which is attributed to the elimination of the nitride precipitation along the grain boundaries and the greater amount of nitrogen retained in solid solution. A mixed mode of intergranular and dimple fracture happen to the specimens before solid solution treatment, while a completely tough fracture of dimple happen to those after solid solution treatment.

Abstract: MSPC techniques are effective tools for detecting the abnormalities of process variation. But MSPC charts do not provide the necessary information about which process variables (or subset of them) are responsible for the signal. In order to identify the process abnormality in covariance matrix of bivariate process, this article proposes a model based on LS-SVM pattern recognizer and |S| chart method, the main property of this model is to identify the assignable causes through LS-SVM pattern recognizer technique when |S| chart issue a warning signal. The simulation results indicate that the proposed model is feasible and effective. A bivariate example is presented to illustrate the application of the proposed model.

Abstract: Aiming at the dynamic integrated scheduling problem of complex multi-products with different arriving time and identical machines, an algorithm is presented by this paper that complex multi-products can be built a virtual manufacturing tree. And the tree will be divided into many subtrees according to the subsection idea. Then these subtrees will be divided into dependent operations and independent operations. Corresponding scheduling strategy is put forward according to the features of operations and the complementarities of identical machines. For dependent operations, forward greedy rule is mainly adopted. For the independent operations, this paper mainly adopts the optimum scheduling rule. Example shows that favorable results can be obtained according to scheduling strategy adopted by this paper.

Abstract: Considering the simple multi-product scheduling problem that there is no-wait constraint between operations, an algorithm is presented which combines the ACPM (allied critical path method) and BFSM (best fit scheduling method) scheduling algorithm. In this algorithm the operations with no-wait constraint and finish-to-start constraint can be converted into a virtual operation. So the scheduling problem with no-wait constraint can be converted into the scheduling problem without no-wait constraint operations but with virtual operations. Then the movement and adjustment algorithm is adopted to sequence the operations which are converted into virtual operation on corresponding machines. So the problem with no-wait constraint between operations can be resolved. Example shows that the method with virtual operations and the movement and adjustment algorithm presented by this paper can be easy to realize, and favorable results can be obtained.

Abstract: In this paper three numerical models , eccentric extrusion method to prepare bending tube ,concentric partial material extrusion method to prepare bending tube, differential velocity extrusion method to prepare bending tube , are built and simulated . Furthermore analyses distribution of material flow velocity filed, load prediction, distribution of simulated tube wall thickness and so on. Though analysis and verification, we can draw the conclusion that three kinds of process methods are feasible, and avoid the quality defect caused by the traditional manufacturing method such as non-uniform wall thickness and wrinkling .They will have practice directive significance for improving bending tube.

Abstract: The constitutive equation of Ti-6Al-3.5Mo titanium alloy had been researched with thermal simulation experiment. The experimental temperature was between 1030°C and 1120°C, and strain-rate was between 0.001 and 1.0, and the deformation degree was 50％. According to Arrhenius　equation, a kind of constitutive equation of Ti-6Al-3.5Mo titanium alloy had been put forward. Compared the calculation results by constitutive equation with experiment results, the relative errors were less than 12%. For Ti-6Al-3.5Mo titanium alloy, strain-rate sensitivity coefficient being m=0.1688, and temperature sensitivity coefficient being s=10233.

Abstract: This work has investigated the performance of Single-walled carbon nanotube bundle as futuristic interconnect material under process constraints and compared its suitability as IC interconnect material as per ITRS predictions. It also analyzes variance of each parasitic effect along with the variations in process parameters. This paper pinpoints the variables causing bottlenecks in realizing optimum performance and improving reliability. It also evaluates the effect of diameter variations of CNTs in an SWCNT bundle and metallic tube ratio on the performance and reliability for 22nm technological node. The results demonstrate that the relative variations in the resistance are critically effected by the variations in metallic tube ratios rather than diameter variations. The diameter variation introduces its critical effect only at global level.

Abstract: Electrodeless resistivity and impedance spectroscopy measurement are reliable equipments of test online for monitoring the hydration process of cement-based materials continuously and accurately. Phosphoaluminate cement (PAC) sets quickly and develops high early strength. In order to understand the mechanism, the hydration products and microstructure formation of PAC in early age need to be studied. In the study, early hydration process and impedance spectroscopy characteristics of PAC with different dosage of retarder were investigated. According to the test, resistivity of freshly mixed PAC paste decreases sharply and then rises slowly, some characteristic peaks appear at different hydration stages of PAC, which indicates the hydration process of PAC includes four stages which are dissolution, induction, acceleration and deceleration. Impedance spectroscopy can reflect the change of micro-structure and ion concentribution of PAC matrix by resistance and capacitance.

Abstract: To make a simulated annealing algorithm(SA) to optimize the method of warping deformation of the purpose is to enable the optimal value of the warpage. Using ActiveX technology and VB programming tools will be SA and Moldflow combination. The optimal injection molding process parameters, such as mold temperature, melt temperature, gate location were determined by according to Metropolis criterion and following a route of Monte Carlo(MC) heuristic random search determined by SA. The results of the typical model show that the wargae is accurate and reliable, and the optimization efficiency is effectively improved by applying the SA method, therefore the combination of Moldflow and SA proposed in this paper is useful for the optimization of injection molding process parameters.

Abstract: The disadvantages of air-conditioner’s triple valve in HPb59-1 alloy processed by traditional solid state hot forging, such as larger forming loads, lower material utilization, larger subsequent machining allowance, nonuniform microstructure, are put forward. However, semisolid diecasting forming which can overcome the above shortcomings is a fascinating technology. The process paremeters which had a larger influence on filling ability of semisolid slurry and casting quality, such as pouring temperature, shot velocity and preheated temperature of the die, were chosen. Furthermore, based on orthogonal test, the semisolid diecasting process of a certain type triple valve was simulated with FLOW-3D. According to the analysis of temperature field, pressure field and surface defect concentration, the optimal process parameters such as pouring temperature 897.25 °C, shot velocity 1.5 m/s and preheated temperature of the die 260 °C, were obtained, and the effectiveness of the technology was well demonstrated by numerical simulation.