Papers by Author: Zong Xiang Yao

Abstract: 10mm thick aluminum alloys 5A02 plates were welded using MIG beam in this paper.The MIG weld formation and microstructure morphology were studied,the hardness in the weld were measured, the tensile test were made.The test result shows that the cooperation of welding current,speed and root gap can lead to perfect welds.There are equiaxed grain in the central welds and cloumnar grain structure near the fusion line.The maximum hardness is in the fusion zone of joints,and the minimum is in the softening zone.

Abstract: The research status of welding process between magnesium with steel have been surveyed．This article detailed the laser welding, Laser-TIG hybrid welding, pressure welding,diffusion brazing. The paper pointed out that it is a prominent problem of magnesium to be oxidated easily and existing intermetallic compound in the joint, which will produce adverse effect to property of welded joint. So how to control morphology and existence state of intermetallic compound (IMC) is the key for quality connectors in joining of magnesium with steel.

Abstract: The TIG welding was used to weld AZ31B magnesium alloys. The results indicate that hot cracking is related to the chemical composition of the filler metal and the welding current. When the AZ40M alloy, with low content of Zn, is used for the filler metal, no hot cracking appears in the weld. While the AZ31B alloy is used as the filler metal, or with no filler metal, hot crack appears in the weld seam.The hot crack will appear when the weleding current is over one point.The reason of hot crack appeared is some low melting eutectic appearing in weld. Key word: TIG Welding;Magnesium Alloys; Hot Cracking; AZ31B

Abstract: The wetting properties of four typical Sn-based solders, i.e., Sn-37Pb, Sn-3.0Ag-0.5Cu, Sn-0.7Cu and Sn-9Zn, on copper (Cu) and aluminum (Al) substrates at 250 °C, 260 °C and 270 °C were evaluated and compared by wetting balance method. The experimental results show that the wetting time of all solders on Cu substrate is shorter than that on Al substrate, but the wetting force of the solders with Cu substrate is bigger than that with Al substrate except Sn-9Zn solder. In addition, the wettability of the solders on Al substrate increases with increasing soldering temperature, and the wetting force of Sn-9Zn increases most obviously among four solders and reach 3.68 mN at 270 °C. The results also show that the wettability of the solders on Cu substrate mainly depends on surface tension of solder alloy, however, it depends on both surface tension and interaction with Al on Al substrate. Due to the active element Zn riches on the surface of Sn-9Zn solder, and Zn solid solutes into Al more easily, the wettability of Sn-9Zn solder on Al substrate is better than other three solders.