부산대학교 도서관

The microstructure and mechanical properties of ZL114A alloy after cold welding were studied by using SEM, EDS, OM, Vickers hardness and WDW-100KN universal tensile tester, the temperature field distribution was calculated by the SYSWELD FEM simulation. The results show that the largest molten pool and peak temperature are 6mm and about 512℃, which are obtained in the 20V and 24A process parameters. The average tensile strength, yield strength, elongation and HV hardness at T6 state are 334,276MPa,7.4% and 68HV, which are changed to 156,108MPa, 12.8% and 60HV after the cold welding process of the ZL114A alloy, leading to a decline of strength by 53.3% and 60.9%, together with an increase of elongation by 72.9%. The same mechanical properties are attained in the cold welding of ZL205A alloy and the normal processing 4mm round hole, the average tensile strength, yield strength and elongation are 232,218MPa and 3.8%. The primary and binary eutectic Si phases are shown as a spherical morphology at T6 state, dimple fracture is the main fracture mechanism, accompanying with numbers of intergranular fracture. The material organization is changed from the T6 state into the solid solution state after the cold welding process, the silicon particles that distributed nearby the grain boundaries are gathered together and the Mg and Si elements are distributed in the grain boundary area coincidentally, the Cu,V and Mn elements are dissolved into the primary Al matrix, some Al2Cu phases are precipitated along the grain boundary.