INVESTIGATION OF HEAT TREATMENT EFFECT ON THE STRENGTH OF Al-Ti BIMETAL HONEYCOMB CORE

摘要

The effect of heat treatment on the strength of aluminium-titanium bimetal honeycomb structures is considered. Aluminuimtitanium bimetal was produced by vacuum diffusion welding of strips of AD1 aluminium and VT1-0 titanium low alloys. The possibility of spot welding of bimetal strips 12 mm wide for producing the honeycomb core was studied with different combinations of titanium and aluminium layers. It is shown that the optimal method is welding the strips in Al/Ti + Al/Ti combination. Here, the average compressive strength of the honeycomb is equal to 41.1 MPa. Annealing of bimetal honeycombs was performed at temperatures of 600°C and 700°C. Annealing time at 600°C was 60... 1200 min., at 700°C it was 10.. .30 min. It is found that annealing for 60 min. at 600°C leads to formation of individual sites of an intermetallic interlayer up to 1 ～m thick in the butt joint between the aluminium and titanium layers that that results in increase of compressive strength of the honeycomb samples by 11,7%, compared to the initial condition. Further increase of annealing time leads to growth of the intermetallic interlayer in the butt joint and to lowering of the compressive strength of the honeycomb samples. It is shown that the honeycomb samples after annealing for 60...600 min at 600°C at compression with the maximum deformation level of 50% deform without fracture of the welding site or bimetal material walls. Increase of annealing time leads to embrittlement of both the welding sites, and the material as a whole.