In order to perform stable pure argon MIG welding, duplex current feeding MIG welding has been developed. In the previous experimental study, higher droplet temperature and deeper weld penetration were obtained in the duplex current feeding MIG welding compared with those of the conventional MIG welding. However, the similar effects are considered to be realized also by the conventional MIG welding with short wire extension through increase in welding current. In this paper, basic characteristics of the duplex current feeding MIG welding were compared with those of the conventional MIG welding with the short wire extension. Consequently, it was found that the duplex current feeding MIG welding achieved the deeper weld penetration without an undercut unlike in the case of the conventional MIG welding with the short wire extension.
Stainless steel features high corrosion resistance but may undergo intergranular corrosion in some specific environments especially in seawater. To cope with this problem, it can be considered to a useful technique to apply titanium material selectively to the part exposed to such specific environments. However, if austenitic stainless steel and titanium are fused together, Fe and Ti create brittle intermetallic compounds, which makes it difficult to configure suitable welding parameters. The authors have studied the laser brazing process to minimize the fusing of the base metal to join the lap joint of stainless steel and titanium.
As the results of examining the base metal arrangement for a lap joint in the use of Cu-Si filler metal, the lap joint with a top plate of stainless steel and a bottom plate of titanium was clarified to be suitable to obtain a crack-free weld joint. The optimum combination of laser brazing parameters with a Cu-Si filler metal was clarified as follows for the present study: 2 kW laser power, 70 degree beam angle, 0.2 mm beam shift, 0.70 m/min brazing speed, and 1.1 m/min filler-metal feed speed by using a semiconductor laser. The examination of several kinds of filler metals verified that the Ni-Cu type and Ni type filler metals increased the formation ratio of Ni-Ti intermetallic compound, thereby causing the occurrence of cracking. In contrast with the filler metals of Cu-Si type, Cu type, and Cu-Ni type, the rupture load fulfilled the JIS standard for titanium clad steel with no cracking in the optimized brazing condition.
In this study, an arc numerical simulation model of xenon short arc lamp was developed by modifying numerical simulation model of free burning arc. The influence of the difference in the filling gas pressure on the energy consumed by the lamp voltage, current and gas radiation was investigated. It became clear that the radiation power of the xenon arc lamp strongly depends on the filling gas pressure. Furthermore, when the lamp is turned on with constant power, the radiation efficiency is determined by the balance between the radiation power density and the high temperature arc volume, and as a result, it is clear that the maximum value exists of the radiation power fraction.
In the newly developed thermal nanoparticle spraying process, micro-composite fragments that contain ceramic nanoparticles can be introduced into a plasma flame to form fine-coating layers at high deposition speeds, by transporting the fragments using conventional powder feeders. In this work, we investigated the effect of the spraying distance, and the nanoparticle concentration in the micro-composite fragments, on the microstructure and mechanical property of the coating. Specifically, micro-composite fragments containing yttria-stabilized zirconia (YSZ) nanoparticles were utilized at concentrations varying between 42-57% v/ v, and spraying distances in the 50-85 mm range. The microstructure of the coated layers was examined using scanning electron microscopy (SEM), and the hardness distributions were measured using a micro Vickers hardness tester.