Abstract: The stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. The formability of AZ31 magnesium-alloy sheet at elevated temperatures was studied first. The experimental results reveal that the forming of AZ31 sheets becomes possible as long as the sheet is heated to an elevated temperature and 200oC is an optimum forming temperature to start with. An optimum stamping process, including die geometry, forming temperature, and blank dimension, for manufacturing the cell phone cases was examined by the finite element analysis. The finite element analyses performed for the cell phone were validated by the good agreement between the simulation results and the experimental data. It also confirms that the cell phone cases can be produced with AZ31 magnesium-alloy sheets at elevated temperature by the stamping process. It provides an alternative to the electronics industry in the application of magnesium alloys.
Abstract: In order to reduce the oxidation and decarburization caused by high temperature in the course of the heat treatment of metal materials, an environment-friendly coating consisting of glass powder and red mud as the main raw materials is applied. It is brushed on the workpiece surface, heated in the box-type resistance furnace.The high temperature oxidation weight gain and the depth of decarburization between naked steel and coating steel are studied using weight gain method and metallographic method. The impact of the coating to reduce oxidation loss and the main properties of coating are analyzed. The result shows that processing properties of the glass-based coating are excellent:it has no crack at high temperature, distributes uniformly on the workpiece surface and can be self-spalling after quenching. It effectively prevents the workpiece from oxidation and decarburization at 800-1100 . The coating is of low cost and easy to use.
Abstract: The sulfurizing layer with a thickness of 8μm was prepared on the netted laser quenching surface of CrMoCu alloy cast iron by means of low temperature ion sulphuration process. The tribological properties of the sulfurizing layer under the condition of dry sliding were investigated by type MFT-R4000 reciprocating friction-wear tester. The morphologies and compositions of the original and worn surface of the duplex coating were analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer attachment (EDX). X-ray Diffraction (XRD) was employed to analyze the surface phase structures. The experimental results revealed that sulfurizing layer was loose and porous, and the phase structure of which was mainly FeS. Furthermore, the sulfide on laser treated area was more compact and the grains more exiguous. Under the same experimental conditions, duplex coating possessed a remarkable friction-reducing effect and improved the wear resistance to a certain extent. And that sulfurizing layer could abate the worn-step effect availably.
Abstract: Multiscale visualization approaches are proposed to efficiently assist designers not familiar with statistical mathematics in determining the optimal process parameter schemes for achieving desired part quality in injection molding, based on which the parameters’ relative importance to part quality and their influence on either single quality index or comprehensive part quality can be visually described by the map of the sum of squared deviations, response surface diagram and distribution map of comprehensive part quality. The proposed visualization approaches are universal for analyzing the effects of process parameters on the quality of any injection-molded plastic parts although the mobile phone cover is utilized as an example in the presentation of our work.
Abstract: The corrosion of aluminum alloy (6262) in artificial sea water under flow condition was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic methods. The flow condition experiments were simulated using rotating cylinder electrode (RCE). Results showed that the increasing of the flow velocity enhances the corrosion kinetic of the system and changes the corrosion mechanism. Limiting current density was increased with increasing in the flow velocity. This behavior was due to the presence of a mixed control on the corrosion process related with the formation and stabilization of corrosion product layers on the electrode surface.
Abstract: The objective of this paper is to study the influence of second peak temperature during simulated welding on properties of the subcritically (S), intercritically (IC) and supercritically (SC) reheated coarse grained heat affected (CGHAZ) zones. This involved heating to a first peak temperature (TP1) of 1400 °C, then reheating to different second peak temperatures (TP2) of 700, 800 and 900 °C with a constant cooling rate of 3.75 °C/s. Toughness of the simulated reheated CGHAZ regions were assessed using Charpy impact testing at 0 and -50 °C. The blocky and connected M/A particles, along prior-austenite grain boundaries, act as a brittle phase for the initiation site of the brittle fracture. Charpy impact results indicated that IC CGHAZ had less absorbed energy with higher transition temperature and hardness.