NON VACUUM ELECTRON BEAM WELDING –A BEAM PROCESS FOR WELDING ZINC COATEDHIGH-STRENGTH STEELS AND STEEL-ALUMINIUM HYBRID STRUCTURES

摘要

In auto body manufacturing, mainly hot-dip coated steel sheets are applied for protectionrnagainst corrosion today. Due to its concentrated energy supply Laser Beam Welding (LBW) isrnan established high performance joining technology for steel sheets and light sheet metals.rnAs additional beam welding technology, Non Vacuum Electron Beam Welding (NVEBW)rnoffers several technological and economical advantages, especially for joining zinc coatedrnsheets and light metals. In comparison to LBW the energy input of the electron beam into arnmaterial surface is higher, which results in a high overall efficiency of NVEBW installationsrnof more than 60 %. Therefore, welding speeds as achieved with LBW can be increased evenrnmore by using NVEBW. Compared to the laser beam, the electron beam on atmosphere has arnmore divergent profile. This guarantees a good gap bridging ability and the welding processrnhas a wide tolerance towards inaccurate positioning.rnThe publication presents the advantages of NVEBW for joining zinc coated high-strengthrnmulti-phase steels on the basis of welding investigations. For this, weldings of hot-dip coatedrnsteel sheets, especially of a micro-alloyed high-strength steel, a dualphase steel, arnresidualaustenite steel, a complexphase steel and a martensitic steel with different seamrngeometries (butt joint, tailored blank, edge-raised seam, lap joint, fillet weld) were producedrnwith good results.rnFor lightweight auto body design, application of steel-aluminium hybrid structures has a highrnpotential. To achieve sufficient mechanical properties of such joinings it is necessary to limitrngrowth of intermetallic compounds between steel and aluminium by an exact energy supply.rnPositive results could be already obtained with laser beam joining. With NVEBW a precisernenergy supply is possible, too. The publication shows successful investigations, where steelaluminiumrnhybrid structures were joined with electron beam on atmosphere. By use ofrnoptimized joining parameters as well as interlayers and surface activators metal combinationsrnwith acceptable mechanical properties were obtained.