Substantiation of electron beam welding modes of a shell-type products work-hardened aluminum alloys AMG6N and AMG6NPP

The problems of selecting the optimum electron beam welding modes of work-hardened aluminum alloy AMg6N and AMg6NPP with varying degrees of hardening (15, 30 %) were considered. The purpose of optimization is to provide the lowest degree of softening and softened zone sizes to ensure uniform strength of welded joints and base metal of shell structures. Particular qualities of manufacturing cylindrical products using electron beam welding are given. We offered a new cooling tool using the screening device and the liquid nitrogen as a refrigerant to reduce the size of softening zones. The principles and operation scheme of the screening device are represented. It is proved that the joint application of tooling and heat-shielding device provides a minimum width of the zone of softening. The results of tests cylindrical samples under biaxial loading for different values of biaxiality are given. According to tests the allowable dimensions of softening zones are defined and the load bearing capacity of welds attenuated softening layers is on the strength level ground hardened metal. The effectiveness of the proposed heat-shielding equipment and screening cap which ensure uniform strength of welded joints and base metal is proved. The obtained results can be used in constructive-technological design and manufacturing of shell products from work-hardened aluminum alloys.