Some Experiments on Properties of Electron-Beam Welds of Reactive Metals and Other Alloys

Studies on Electron-Beam Welding, 6

Abstract

Chemical compositions, porosities and mechanical properties of electron-beam welds were studied of ractive and refractory metals, aluminium alloy, stainless steel and carbon steel by comparing with controlled atmosphere TIG welds and the following conclusions were obtained :
(1) The contents of oxygen and nitrogen in titanium and zirconivm were changed neither by electron-beam welding (EBW) nor by TIG.
By EBW, contents of carbon and oxygen in sintered niobium sheets, that of carbon in a sintered tantalum sheet and that of nitrogen in a type 304 stainless steel plate were considerably reduced.
(2) X-ray radiographs of both EBW and TIG welds in sintered niobium, molybdenum and tungsten sheets showed usually many porosities in weld metal near the fusion line, while porosityfree welds were obtiand in vacuum melted sheets.
Repeated electron-beam bead welding in sintered sheets was very effective in eliminating porosities in weld metals.
(3) An element of which the partial pressure at melting point of a base metal is higher than about 10^-2mmHg is likely to be vaporized during EBW in a vacuum of (1-5) × 10^-5mmHg.
(4) Subsize V-charpy impact values of commercially pure titanium, zirconium and Zircaloy-2 plates were generally far greater in EBW welds than in TIG welds.
(5) Brittle behavior of arc welds of molybdenm sheets was not improved by EBW, probably because of grain coarsening in weld zone.
(6) The joint efficiency of EBW, welds of a 1 mm thick 24 S aluminum alloy sheet was about 87% and much greater than 50 to 70% in TIG welds, owing to the very narrow width of weld metal and heat-affected zone.
(7) The joint efficiency of EBW weld of a 6 mm thick 17-7 PH plate was 100% and was greater than 95% in TIG weld.