Optimizing of Solution Aging Heat Treatment Process on Ti-6Al-4V Alloy Thick Plate by Orthogonal Test

Four influencing factors, such as solution temperature, cooling mode, aging temperature and aging time, were determined by introducing the orthogonal test in the process of heat treatment parameter selection, and 16 groups of heat treatment processes with 4 factors and 4 levels in L16 (4⁴) orthogonal table were used to optimize the process. The results show that under the test conditions, the order of the influence of various factors on transverse and longitudinal room temperature strength of the plate from large to small is cooling mode, aging temperature, aging time and solution temperature, but they have no effect on the room temperature plasticity. The cooling method after solution has the greatest influence on the tensile properties of plate at room temperature, with the increase of cooling rate, the transverse and longitudinal tensile strength and yield strength of plate are greatly improved, the elongation after fracture and reduction of area have a litter fluctuate. The effect of aging temperature on the tensile properties of plate at room temperature is the second, with the increase of aging temperature, the transverse and longitudinal tensile strength of plate shows a down tending, the elongation after fracture has no changing, while the yield strength and reduction of area increase slightly and then remain unchanged, and reach the maximum value at 550 ℃. Under the test conditions, the optimal solution aging heat treatment process of Ti-6Al-4V alloy hot-rolled plate is 900-960 ℃/1.5 h, water cooling+550 ℃/4-6 h, air cooling.