| Summary: | 碩士 === 國立交通大學 === 機械工程系 === 91 === The effect of adding activating fluxes on the morphology, distortion in austenitic stainless steel were investigated. An autogenous gas tungsten arc welding was conducted on type 304 stainless steel . activating fluxes of oxide, Carbonate and fluoride where used to produce a bead-on-plate weld. The experimental results indicate that the activating fluxes SiO 、Cr O , and TiO can give a full penetrated, narrower heat-affected zone, and beneficial effect on reducing angular distortion in stainless steel weldments under the same welding process parameters. Furthermore, the SiO can obtain a full penetration and lower distortion in TIG-flux stainless steel weldment. It was also found that the fluxes of SiO ,Cr O , TiO , CaF and NaF can not cause a significant change on microstructure and mechanical property in austenitic stainless steel welds. By increasing welding current, the oxide flux can create wider heat-affected zone,and weld convex length. In addition, the half of proportion on depth/width ratio and depth/thickness ratio can give the maximum of angular distortion. Furthermore, the oxide flux can obtain a phenomenon of undercut in TIG weldments of stainless steel under increasing welding current up to 200A.
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