Effect Of Parameters And Temperature Distribution On Microstructure And Mechanical Properties Of Welded Joint During PAW Of SiCp/6061Al

In this paper, a systematic study on effect of welding parameters (welding current, welding velocity, thickness of alloying filler, shielding gas) on the microstructure and distribution of welded joint in plasma arc welding for SiCp/6061Al was conducted with or without alloying filler Ti.The analysis on plasma arc welding for SiCp/6061 Al without filler showed thatdue to higher heat input, matrix Al and reinforcement SiC generate interface reaction(3SiC+4Al=Al₄C₃+3Si), generating harmful fragile phase Al₄C₃, the number ofSiCp falling down and presenting local aggregation. Because of these reasons, thetensile strength of welded joint was decreased.So SiCp/6061 Al was welded by plasma arc with alloying filler Ti and the ionized gas was changed from simple Ar to N₂+Ar mixed in certain proportion. The results showed that due to the presence of alloying filler Ti and N₂, the harmful interface reaction was effectively restrained; the flowing property of molten pool was improved; even fresh reinforcing phases such as TiC, TiN , AlN generated in welded joint. Whereas the performance of welded joint were improved to 65% of base metal. Further studies showed that species and distribution of reinforcing phase are principle factors for effect on performance of welded joint in "In-situ" weld-alloying/PAW of SiCp/6061 Al.In order to analyzed the effect of welding processing parameters on species and distribution of reinforcing phases visually and legibly, finite element software ANSYS was used to simulate transient temperature field for SiCp/6061 Al in "in—situ" weld alloying/plasma arc welding. The results showed that the calculated results approximately agreed with the experimental measured results. So the model was basically correct and credible. Based on the numerical solutions and experimental results, effect of temperature field in different welding process parameters(welding current, welding velocity) on species and distribution of reinforcing phases was analyzed. The results show that adjusting and optimizing temperature field appropriately is an effective method to obtain welded joint with better microstructure and performance.