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

  • 摘要: 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.

     

    Abstract: 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 β phase, 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.

     

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