This article proposes a novel method for analyzing residual stress and deformation in butt welding on 6 mm SUS304 stainless steel plates, using MSC.MARC, a commercial finite element method software, to find the best location for jig fixtures that will minimize welding deformation. Simulation and experimental studies show that a distance of 100 mm between the jig center and the welding bead center is best for inhibiting welding deformation when the jigs experience downward displacement at 0 mm on the steel plate; the total displacement is only about 1.1 mm in the case of a 300 × 250 × 6 mm SUS304 steel plate. In addition, a numerical model shows that four jigs with pitches of 200 mm can better reduce welding deformation than six jigs with pitches of 100 mm. The largest residual stress after welding occurs around the weld bead center, and the residual stress away from the welding bead center increases gradually when jigs have been applied on the steel plate to prevent deformation. The reaction force of the jigs on the steel plate has no further effect in reducing deformation. We conclude that commercially available jigs can inhibit deformation during the welding process.

Featured Application: The proposed method may benefit the cleaning process of the metals that undergo surface treatment. Especially, this method can be used to fabricate microstructures on the surface of the stainless steel to enhance the self-cleaning and corrosion resistance properties.Abstract: This research utilizes a plasma electrolysis technique to clean the surface of stainless steel 316. The resulting microstructure enhances the self-cleaning properties of the stainless steel surface. The position of the cathode electrode is varied to enlarge the total surface being processed and achieves a uniform processing surface. We propose a self-made plasma electrolysis reaction system supplemented with a 3-axis platform to control the speed at which the cathode electrode moves. The electrolyte is an aqueous solution of sodium bicarbonate (NaHCO 3 ) and water. We obtain the optimal parameters for applied voltage, moving speed of the specimen at the cathode, and electrode distance using a one-factor-at-a-time experimental approach to achieve uniform distribution of the surface microstructure. We then observe and measure surface micrographs showing the surface roughness of the specimens after experiments, using a scanning electron microscope (SEM) and an atomic force microscope (AFM). The contact angle is experimentally proven to be greater than 100 • , indicating that the surface is hydrophobic.

A thermo-elastic-plastic finite element model was employed to simulate and analyze the effects of high-power parameters on the laser heat treatment of AISI 1045 steel. Tempering effects of multitrack laser heat treatment using various process parameters-laser power, laser feed rate, laser overlap rate, and laser spot size-were analyzed to estimate the distribution of a hardening layer on the steel surface. Numerical simulation results indicated that the proposed finite element model is effective in analyzing the laser heat treatment of the steel surface and calculating the possibility of decreases in steel hardness due to tempering effects, enabling it to undergo rapid temperature increases and decreases.

To protect the environment, the use of mercury tubes has been prohibited in Europe since 2000. As an alternative, phosphor-doped silicone resin wheels have been used to convert blue-ray laser diodes. However, high-temperature photonic decay and cracking on the lens surface significantly degrade transmission. Recent research has explored the possibility of replacing the silicone encapsulant material of the phosphor layer with glass. In this study, the thermal effects of a glass-based phosphor-converted color wheel (GP wheel) and a silicone-based phosphor-converted color wheel (SP wheel) were investigated using various parameters and geometries. A thermal-structural coupling finite element (FE) model of the color wheels was employed to simulate the thermal and stress distributions. To construct the FE model, experiments were conducted and the inverse engineering approach was employed to extract the optical-to-heat conversion coefficient and the heat convection coefficient. In addition, an arc-shaped moving input heat flux was used to simulate a moving laser input and reduce the calculation time of the FE model. Based on the numerical and experimental results, the FE model developed can simulate the steady/transient behavior of the resin and the GP wheel. In addition, the results reveal that thermal failures of the SP wheel are very likely to occur under all parameters employed in this study, whereas the maximum temperature of the GP wheel reaches only approximately 40% of the glass transition temperature. The numerical results indicate that the GP wheel may be useful for overcoming all of these thermal disadvantages in a high-power laser-lit projector.

This paper describes the use of a plasma electrolysis technique to apply a nanosilver coating to the surface of stainless steel to achieve hydrophobic properties. We propose an experimental reaction system, which includes stainless steel 316 as the two electrodes and an aqueous solution of potassium nitrate (KNO 3), silver nitrate (AgNO 3), and ammonium hydroxide (NH 4 OH) as the electrolyte. Better results with a stainless steel surface coated by nanocrystalline Ag film are obtained using optimal parameters chosen through one-factor-at-a-time experiments. The main parameters consist of electrode distance, KNO 3 concentration, and AgNO 3 concentration. The experiment focuses on analyzing the impact of the plasma electrolysis technique on processing time. Variations in KNO 3 concentration show that 3 wt.% yields the worst result because it causes an uneven surface, whereas 5 wt.% gives excellent results because it creates an even, porous surface and the highest contact angle. An AgNO 3 concentration of 0.03 wt.% yields the best contact angle. With the same processing time, silver sediment increases as the KNO 3 concentration increases. With respect to variation in electrode distance, we find that when the distance is set at 20 mm, the contact angle exceeds 100 • and results in hydrophobic properties on the specimen surface, while other distances yield a contact angle below 80 • , resulting in hydrophilic surfaces. The SEM (scanning electron microscope) results show that the surface of the specimen is full of crater-like cavities that directly affect the contact angle. In this experiment, the contact angle yielding optimum hydrophobic properties is 134 • ± 10 •. Finally, using distribution patterns obtained by elemental analysis, the experimental results lead to an evenly distributed silver coating on the surface of specimens subjected to plasma electrolysis treatment. The study confirms that plasma electrolysis can be used to coat nanosilver onto stainless steel 316.