Heat treatment method of Ti-6Al-4V (Ti Grade 5) , BT9 titanium alloy forgings

Ti-6Al-4V (Ti Grade 5) alloy is an alloy of titanium, the metal element that makes up titanium alloy bars. It is a kind of Ti-Al-Sn-Zr-Mo-W-Si alloy series α+β type thermal strength titanium alloy with excellent comprehensive function. It has both the high thermal strength of titanium Grade 2 alloy and the thermal stability of titanium Grade 1 alloy, and is suitable for long-term work at 500 ~ 550℃. It is reported that the working time can reach 6000h below 500℃ and 3000h at 550℃. Therefore, Ti-6Al-4V (Ti Grade 5) alloy is the ideal thermal strength titanium alloy for engine, which can be used to manufacture aerospace engine compressor parts. The alloy can be processed into forgings, bars, die forgings and other forms of products.

The researchers studied the effect of different solution temperature and cooling method on the structure and function of BT25 titanium alloy forging. The results show that the microstructure of air-cooled is finer than that of furnace cooled under uniform solution temperature. The solution temperature is above the phase change temperature, and the strength of air-cooled is higher than that of furnace cooled at room temperature, but the impact toughness and plasticity indexes change little. The phase change temperature is above the solution temperature, the strength of air-cooled solution is slightly higher than that of furnace cooling at room temperature, the impact toughness and section shrinkage are much higher, the elongation changes little, but the yield strength decreases slightly. The high temperature strength showed a slight improvement trend with the improvement of cooling speed, and the plasticity index did not change significantly. The solution temperature is 30 ~ 40℃ below the phase change point, the insulation 2h air cooling +550℃, and the 6h air cooling and heat treatment rail system can ensure the best match between the plasticity and strength of the alloy.