In the manufacture of marine engineering ships, the most used material is aluminium alloy 5083 h112 plate, accounting for about 55% of the total consumption. The thickness of the aluminum 5083 h112 plate is 4.5mm~170mm, and the thick aluminum plate 5083 of 170mm is used to manufacture huge storage tanks on LNG (liquefied natural gas) carriers.

In addition to precisely controlling the composition of the aluminium alloy 5083 h112 plate in production, special attention should be paid to the solution purification treatment, because the high Mg content of the alloy is easy to oxidize and absorb hydrogen. The ingot homogenization temperature is 455℃, and the holding time is 32h. It can also be at (460℃~470℃)/(15h~20h). The furnace temperature should be uniform, preferably ±5℃.

5083 h112 alloy is hard alloy, it has many hot rolling passes, and the total processing rate of the first 5 passes is only about 15%. When hot rolling on a single stand, the average machining rate of the last 5 passes should not exceed 25%. , When rolling on the (1+4) continuous rolling mill, the rolling rate of the fourth finishing stand should not be > 40% or 35%. Usually hot rolled coils need to be annealed before cold rolling. When cold-rolling thin strips, intermediate annealing is also performed. In the production of 5083-0 alloy thin strip, special attention should be paid to the control of finished annealing process parameters. The furnace temperature must be uniform, and the strip or sheet should be in a completely recrystallized state, otherwise it will crack during subsequent bending. The temperature deviation in the furnace should be ≤5℃, the charge should not be too much, the height of the plate stack should be moderate, and the plate temperature can be released when the temperature reaches 345℃. If necessary, it can also be kept for about 20 minutes. For the sheet with bending process, its tensile strength Rm and yield strength Rpo.2 should be controlled at the lower limit of the standard value, and Rm should preferably not be greater than 300N/mm2.

The production of aluminium alloy 5083 h112 plate products with mechanical properties that meet the standard requirements and no stress corrosion cracking, spalling corrosion susceptibility, especially thick or thick aluminium plates with high magnesium content, must be achieve four points: first, precise chemical composition, thorough purification treatment, uniform and fine crystalline structure; second, precipitation (precipitation) phase (Al3Mg2) is finely dispersed in the grains; third, there is no residual stress; four corrosion test should be carried out according to relevant national and industry standards. This is a very troublesome and protracted work.