Technology And Mechanism On Argon Arc Welding Of Sic Particle Reinforced 6061 Al Composites

In this paper, 6061Al composites reinforced with SiC particles formulated by powder metallurgy approach as experimental material was welded successfully by both TIG and MIG welding. 5356 and 4043 wires which are most frequently used as filler in 6061 aluminum alloy welding were both experimented in the two welding processes. Finally, welding with ordinary solid wires can get a fairish welded joint, but make no sense to the distribution of reinforced phase. As a result, a self-made in-situ reinforced wire was manufactured to increase quantity of reinforced grain. Mechanical properties of welded joints were measured by tensile test, and the microstructure of welded joints of composites was observed by optical microscope, scanning electron microscope and X-ray diffraction.Due to the result of TIG and MIG welding, a comparison comes: during TIG welding, because of the lower heat input,less continuous filler input,more susceptible by anthropogenic factor, incorrect weld profiles such as pore and incomplete penetration were more frequently observed ; However , due to higher heat input and more continuous filler input in MIG welding, better weld profile with less imperfection was observed.Due to the result of TIG and MIG welding with 4043 and 5356 wire, compared with 5356(Al-Mg) filler, 4043(Al-Si) filler can improve molten pool fluidity, restrain interface reaction and generate less acicular phase Al₄C₃. AS a result, better weld profile was observed and higher tensile strength of weld joint was obtained, especially during higher heat input of MIG welding.Though a fairish forming of weld could be obtained by MIG welding with Al-Si filler, because of the lack of and heterogeneous distributed reinforced grains, tensile strength of weld joint could not be improved further, and then "in-situ reinforced" was advanced to deal with the problem. "in-situ reinforced" , it means on the base of improving molten pool fluidity, as well as, adding reinforced grains by chemical reaction in the weld pool during welding. The results of experiment show that better weld profiles and higher tensile strength can be obtained, because of SiC particles and TiB₂ particles in the weld joint, when using self-made in-situ reinforced wire which contains Si, SiC, Ti and B element.