Advanced Materials Research Vols. 154-155

Abstract: This article describes the overall processing technology of the ultra-long cylinder, especially the internal pull the hinge hole processing technology from the tooling, cutting tools to machining parameters are introduced in detail to solve the difficult problem of processing very long hole, cylinder machining accuracy is guaranteed.

Abstract: This study mainly investigates the characteristics of carbide and the matrix structure of ASTM A532–87 CLASS Ⅲ high-chromium white cast iron under directional solidification. The two components of high-chromium white cast iron were put in a 3-level Furan sand model, which is placed in a cold-water circulation copper model, producing unidirectional chilled solidification. A K-type thermocouple is employed to measure data for solidification temperature with time. The move velocities of the liquidus phase and solidus phase is calculated. The matrix and the growth characteristics of M7C3 carbide are explored. As determined from the experiment, the liquidus temperature gradient GL is 0.45~ 0.9oC/mm, and the solidus temperature gradient Gs is 4.3~6.2oC/mm. Around 300 nm of the primary carbide is formed from the added elemental nickel being less than 0.3 mm from the chilled end and from the nickel-free alloy being less than 5 mm from the chilled end. As the distance from the chilled end increases, the primary carbide gradually becomes coarser, and the distance between eutectic carbide groups is increased. This study employs EPMA to analyze the changes of primary carbide, eutectic carbide and matrix components with distance from the chilled end, as well as changes in the distributions of chemical elements.

Abstract: Using finite element method, a numerical simulation is presented for engine block casting. The filling process analysis provides an accurate initial temperature field to the thermal stress and hot tearing investigations; meanwhile, it is useful in prediction of cooling shut. The thermal stress distribution after solidification of the casting is solved. To assess the hot tearing, the RGD criterion is adopted. Both hot tearing indicator and thermal stress can be used to estimate the susceptibility of hot tearing. The results can offer a reference to casting parameter design for engine block.

Abstract: The temperature evolution in inertia friction welded Inconel 718 joint was measured by means of embedding thermocouples in specimens. The spatial distributions of temperature in the axial and radial directions of weldments were obtained and the varying characteristics of the temperature distributions were analyzed. The results indicate that the heating rate during the inertia welding process decreases gradually. The temperature distribution in the radial direction of weldment is uneven and the temperature rises gradually with the increase of distance from the center. But the relation between the temperature and distance is nonlinear. In the axial direction, the shorter the distance from the initial friction surface is, the bigger the rate of temperature increment becomes and the higher the peak temperature and the temperature gradient are. Meanwhile, the longer the distance from the initial friction surface is, the later the peak temperature appears and the longer the delay time gets. Moreover, the results of microhardness testing in a welded joint prove that the measurement of temperature in this study is reliable.

Abstract: Take knitting seamless underwear material as subject of studying, approach the influence of stereotypes parameters on seamless underwear stereotypes. Orthogonal Analysis is used to analyze the experimental results to achieve the excellent parameters attaining the best appearance effects and hand feel of seamless underwear, that is: stereotypes temperature 150-170 , Time 2s, Pressure 4Kgf/cm2. The conclusion will take a lead for the seamless cloth enterprise to improve product quality.

Abstract: The structure of chemical sensor has great influence on the performance of the sensor. This article presents an optimum design method to improve dynamic stiffness of the sensor structure. The original resonance frequency and modes shape of the structure are obtained by the finite element analysis. Then a series of reasonable parameters are determined by optimum calculation. In the end, the result of the random vibration analysis verifies that the performance of chemical sensor structure for food hazard detection is improved greatly by the presented method here.

Abstract: In this paper, the specimens of GCr15 steel were quenched by laser transformation hardening experiment and then they were tempered at different temperatures. The tempering micromorphology and microstructure of laser surface hardening layer were studied, and the photos of scanning electric microscope(SEM) were used in the fractal analysis. The relationship between the tempered temperatures and the hardness of the hardening layer surface was researched, and the relationship between the hardness of the hardening layer surface and the fractal dimension of the surface hardening layer SEM photos was also researched.

Abstract: In order to improve the sensitivity of MEMS temperature sensor, this paper proposes an efficient and robust structural optimum design method for the sensor structure. Based on thermal analysis of software ANSYS, the thermal deformation and distribution of temperature field can be obtained clearly. A predictive model for thermal deformation is established using artificial neural network and the sample for neural network model is designed by using orthogonal experimental method. In the model, the structure parameters of sensor are treated as design variables and the objective is to obtain the maximum deformation. Optimization of structure parameters for sensor was conducted by introducing artificial neural network prediction models into genetic algorithm. The results indicate that the optimization method based on artificial neural network and the genetic algorithm is feasible for improve the sensitivity of chemical sensor.

Abstract: The correct selection of the machining parameters is one of the most significant issues to take into consideration in Ultrasonic-assisted Electrical Discharge Machining (US-EDM) and EDM processes. In the present work, a study has been made to develop and extract statistical models to show the relationship between important machining performance data (material removal rate (MRR), tool wear ratio (TWR) and surface roughness Ra) and the input machining parameters (pulse current, and pulse-on time) in the EDM and US-EDM of AISI H13. The models obtained were used to analyze the effects of input parameters on machining performance. In addition, a comparative study was carried out to investigate the effect of ultrasonic vibration of the workpiece on machining performance. The results show that Ultrasonic vibration of the workpiece can significantly reduce the inactive pulses and improves the stability of process. Also US-EDM is effective in attaining a high material removal rate (MRR) in finishing regime in comparison with conventional EDM. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models can adequately explain the performance within the limits of the factors being studied.