The Technology Research On Brazing Of Aluminum Alloy And Tainless Steel

Welding structure with aluminum alloy and stainless steel has good performance, suchas corrosion resistance and light weight, and plays an important role on material-saving andrational use of resources, therefore, the two composite should have broad applicationprospects. However, in physical and chemical property aspects of the great differencesbetween them, it is difficult to use normal welding method to connect aluminum alloy andstainless steel. In this paper, Cu foil and Al-Si alloys were used as interlayer separately,Nickel was plated on the stainless steel, test of vacuum brazing of6063aluminum alloy and1Cr18Ni9Ti stainless steel was conducted on different condition of specific processingparameters. Microstructures, the distribution of elements and mechanical properties ofsoldered joint were analyzed by means of SEM, EPMA and OM.The analysis of microstructures and mechanical properties test of the6063alloy/Al-Sigold foil/1Cr18Ni9Ti stainless steel joint show that the heating temperature, high and low,and the holding time, long and short, have a great impact on microstructure forms andmechanical properties; The microhardness of welding seam is obviously higher than that of6063aluminum alloy and1Crl8Ni9Ti stainless steel substrate, meanwhile, the higher thetemperature is, the higher the microhardness of the interface zone is, the main reasons arethe generation of brittle Fe-Al intermetallics layer on1Cr18Ni9Ti stainless steel side and theexisting of a good many brittle Si;The soldering6063aluminum alloy/Al-Si and gold foil/Niplating layer/1Cr18Ni9Ti stainless steel results showed: Ni plating layer can effectivelyblock the spread of Fe atoms; by means of theoretical calculation，When solderingtemperature is580℃, Fe need65min to pass through10μm thick Ni plating layer; Whensoldering temperature is600℃, Fe need26min to pass through10μm thick Ni plating layer.The results of the6063aluminum alloy/Cu plating layer/1Cr18Ni9Ti stainless steelbrazing test and wettability test of Cu on6063aluminum alloy shows that the wettability ofAl-Cu eutectic liquid on6063Al alloy matrix is fine, which results from combined action ofwetting spreading and reactive spreading; Whether the soldering temperature excessiveincreased or the holding time unlimited extended, the performance of brazing joint maydamage, the main reason is that the increase of intermetallic thickness on the stainless steelside and grain boundaries penetration on aluminum alloy substrate side; Grain boundarypenetrating phenomena aggravates with soldering temperature increasing and holding timeextension. When it get to the limit process parameters, crack appears, then the weld joint become invalid; In the same region, micro hardness of joints on soldering temperature600℃was bigger than that on soldering temperature580℃. The concentration distributions ofFe、Al element in intermetallics of FeAl3and AlCu2are analogy calculated, and comparedwith EPMA actual measurement data, it shows that the theoretical calculation value isbasically consistent with the measured value.But the observed data of the Fe, Al elementsspread width than the calculated element distribution transition zone width, although thereare some errors, but overall, in the interface transition zone of the6063aluminum alloy/Cuplating layer/1Cr18Ni9Ti stainless steel brazing joint,Fe,Al elements of the diffusion rulecan through the Fe, Al basic element diffusion equation shows.