Aluminum alloy has been widely used due to its excellent workability, and double-pulse metal inert gas welding (MIG) has become a popular technique in aluminum alloy welding. In this study, a cross-complementary test was performed to study the effect of double-pulse characteristics on weld bead formation and mechanical properties in MIG welding. The test was carried out on an AA6061 aluminum alloy using flat overlaying welding. After welding, the micro-metallographic structure and macro-mechanical performance of the weld bead were explored. The test results showed that the two methods of increasing the base current amplitude or the low-frequency of the current effectively enhanced the oscillation of the molten pool, refined the grain size of the fusion zone, and improved the mechanical properties of the weld. Additionally, by comparing the macroscopic photograph of the specimen and the corresponding welding parameters in the test, the formation characteristics of the bead’s fish-scale pattern in double-pulse MIG welding were found when appropriate welding parameters were adopted and weld bead formation was good. This test result provides a strong scientific basis for the selection of welding parameters in the actual promotion and application of double-pulse MIG welding.
Curcumin loaded octenylsuccinate fish scale gelatin (OFSG) was prepared in this study, to explore the potential of FSG for delivering hydrophobic nutrients. The effects of molecule weight (Mw, 22,677–369 g/mol) and degree of substitution (DS, 0–0.116) on the curcumin loading efficiency (CLE, μg/mL) of OFSG (6.98–26.85 mg/mL) were evaluated. The expose of interior hydrophobic groups in FSG and increased intermolecular hydrophobic area contributed to the loading of curcumin in two phases, respectively. The interaction between OFSG and curcumin showed a decreased absorption in FTIR and an increased crystallinity in XRD. The loading of curcumin into OFSG caused a significant decrease of the particle size (from 350–12,070 to 139–214 nm), PDI (from 0.584–0.659 to 0.248–0.347) and ζ-potential (−12.2 or −11.4 to −21.0 or −20.3). OFSG showed a significantly higher stability and lower release of curcumin than FSG at the end of the simulated gastrointestinal digestion. Thus, OFSG showed great potential in the construction of a carrier for hydrophobic nutrients.
Double-pulse gas metal arc welding (DP-GMAW) is a common low-melting-point metal welding method. In this study, a low heat-input double-pulse gas metal arc welding (LHDP-GMAW) was proposed based on DP-GMAW. The welding process stability, weld bead shape, microstructure, and microhardness of 6061 aluminium alloy welding were analyzed for DP-GMAW and LHDP-GMAW with different low-frequency (3, 5 and 7 Hz). Compared with DP-GMAW, the stirring effect of alternating strong and weak pulses on the molten pool of LHDP-GMAW is enhanced and the heat input is reduced. Therefore, the LHDP-GMAW can produce more obvious fish-scale ripples, lower penetration, smaller and more uniform grains, and higher microhardness. This study provides a new solution for improving the welding quality of low-melting-point metal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.