The Development of Procedures for the Explosive Weld Cladding of Magnesium Compressor Casings.

This report describes the experimental procedures, evaluation, and results of the program to demonstrate the feasibility of explosively welding aluminum alloy liners into the blade retaining grooves of EZ33A-T5 magnesium alloy compressor casings. Two groove configurations were investigated, the rectangular and T-shaped configuration. An explosive was developed to meet the requirements of explosive welding the liners into the complex shaped low ductility magnesium casing. A blend of ammonium perchlorate AP - pentaerythritol tetranitrate PETN in the ratio of 75 wo AP-25 wo PETN was found to reliably produce detonation velocities in the range of 2000-3000 msec. in thicknesses of 0.5 to 0.64 cm. Preliminary experiments revealed that a thin layer of aluminum alloy could be explosively welded to EZ33A-T5 magnesium alloy without cracking if 1 the magnesium were heated to a minimum of 150 degrees C prior to welding and 2 the magnesium was well supported by rigid tooling. Groove welding experiments with both flat plates and curved segments revealed that L shaped liners could be successfully welded into each half of a rectangular groove with a minimum of distortion and no corner cracking, if rigid support were provided for the magnesium. The T groove configuration, however, required a slightly greater explosive thickness which resulted in increased deformation and corner cracking in the magnesium.