循环热处理及形变对TC17钛合金片层组织球化和取向的影响

Effect of cyclic heat treatment with hot deformation on the microstructure and structural orientation of TC17 titanium alloy lamellae

将循环热处理与形变相结合,利用电子背散射衍射等手段探究该工艺对TC17钛合金片层组织球化和取向的影响.结果表明:TC17钛合金在两相区进行单纯的循环热处理其片层组织球化程度有限,而经过循环热处理+压缩变形后,其魏氏组织消失,片层α相得到明显球化,但是其取向均匀性仍没发生较大变化.此外,变形中两相的再结晶速度及其强韧性导致了两相取向的差异性.α相的再结晶速度快于β相,在变形过程中,α相的各向异性首先降低;另一方面,由于α相比β相硬度高,热变形过程中,α相的变形程度小于β相,应变主要集中在与α相邻近的较软的β相,从而导致α相的取向均匀性高于β相.

The effects of cyclic heat treatment and hot deformation on the spheroidization and orientation of the TC17 titanium alloy were investigated using a light microscope（LM） and electron backscattered diffraction（EBSD）. The experimental results indicate that in the two-phase temperature range of a simple,cycle heat treatment,the spheroidization of the lamellar microstructure of the TC17 titanium alloy is finite. After cyclic heat treatment and compression deformation,the Widmannstatten structure disappears,the spheroidized α lamellae is more obvious,but the uniformity of its orientation is not greatly improved. In addition,the recrystallization velocity,and the strength and toughness of the two phases in deformation lead to a difference in their orientation,and the recrystallization velocity of the α phase is faster than that of the β phase. In the deformation process,the anisotropy of the α phase is preferentially reduced. On the other hand,during the hot deformation process,the degree of deformation of the α phase is lower than that of the βphase,because the α phase is harder than the β phase. The strain is primarily concentrated on the softer β phase adjacent to α phase,which produces greater uniformity in α phase than in the β phase.