TWI Industrial Member Report Summary 265/1985
By A Sanderson and P J Blakeley
Electron gun discharge tendency has been studied during the welding of a wide variety of common engineering alloys, including mild, low alloy and stainless steel; titanium, copper, magnesium, aluminium and their alloys. Comparisons were made for fully penetrating welds in several thicknesses and also under beam fade-in conditions and at low current level. From this it has been possible to classify alloy groupings in order of difficulty. For materials and thicknesses where excessive gun discharging occurs, with a conventional electron column, a magnetic trap device has been shown to eliminate discharge events almost entirely. Comparison of fusion zone width, without and with the magnetic trap device, generally indicates no undue beam aberration effects.