Papers by Author: Xiao Mu Zhang

Abstract: Thermal simulation and arc welding were carried out to test the weldability of atmospheric corrosion resistant steel 07MnCuPTiNb. In thermal simulation experiment, welding thermal cycles with different peak temperature and different cooling rate were adopted and the microstructure and impact toughness were analyzed. In arc welding experiment, different heat input was used and the microstructure, impact toughness, hardness distribution, tensile strength and bending ductility of welded joints were examined. When small heat input is used for welding, the impact toughness of HAZ remains to be good. The broken position of tensile test specimen is located in base metal zone. The joint also has good ductility.

Abstract: Aluminum alloy has being widely used in modern automobile and aeronautic industry. However, the welding of aluminum alloy, especially high strength aluminum alloy，is difficult. Porosities are usually brought in the weld metal. In this paper, MIG welding using mixed gas shielding is carried out. The characteristic shapes of porosity in weld metal are described, the mechanism of porosity formation is analyzed, and the factors that influence the tendency of porosity formation are studied. Experiment results indicate that by the use of mixed shielding gas of 38%He+62%Ar, the number of porosity is reduced, the width of HAZ and softened zone is decreased, and the mechanical properties of welded joint is increased.