Zhen Luo

Effects of Rare Earth Elements Erbium and Cerium on the Properties of Hardfacing Alloy

By the way of adding rare earth element into the coating of electrode, this article has studied the effects of rare earth element erbium and cerium on the properties of welding surface. Experiment results show that adding rare earth element to the welding rod coating could make the grains fine, increase the content of acicular ferrite and improve the hardness and abrasion resistances of weld metal. After joining 0.3% Er and 0.3% Ce, the weld metals macroscopic hardness achieves 39HRC, enhanced 23.8%. And the relative wear resistance enhanced 25.6%

Propagation Character of the Stress Wave in Weld Joints

Stress wave test technique has broad prospects because of the long distance, large scale and relatively low cost. This paper studies the stress wave propagation characteristics in the butt weld joints in the case of external symmetrical impact. The stress wave propagating before and after the joints is measured by dynamic strain gauge. Then model analysis and simulation is applied to research stress wave. The results show the loss of stress wave is small. After spectrum analysis, the change of propagating stress wave can be detected.

Study of the Effect of Active Fluxes in Gas Tungsten Arc Welding

In order to investigate the effect of active fluxes on weld penetration, angular distortion and weld morphology in gas tungsten arc welding (GTAW), three types of oxide fluxes-CaO, TiO2 and Al2O3-were used in the welding of 5mm think stainless steel plates. Those powders were applied through a thin layer of the flux to produce a bead on plate welds. The results showed that compared with conventional TIG welding, increased weld penetration and reduced angular distortion of the weld piece were obtained with the application of active fluxes. However, the weld morphology was not changed significantly when the powders were coated on the surface of steel. It was also found that each of the powders has a fittest range in penetration increment. Whether the rate of the coating run out of the range, the effects of these active fluxes on the increased weld penetration were not obvious. The CaO flux has a narrow effective range for deep penetration, while the Al2O3 powder does have no effect on A-TIG penetration. The mechanism of those different performances has not been found out. According to the investment, the mechanism of active fluxes for the increased weld penetration and reduced angular distortion is related to the contraction of the arc.

A Welding Method for Carbon Nanotubes to Metal

A simple ultrasonic welding method was employed to bond the carbon nanotubes and metal electrodes, at the same time, macro-body carbon nanotubes was tried in the experimental. By the welding head exert suitable pressure on carbon nanotubes bridge on electrodes with frequency of 60 kHz and power of 1.8w, contact would be achieved between these, moreover, the image of SEM show that the bonding was tightly.