近β型TLM钛合金细径薄壁管材力学行为研究

Study on Mechanical Behavior of near β-Type TLM Titanium Alloy Tube with Small Diameter and Thin Wall

摘要:

利用冷轧与中间退火获得近β型TLM钛合金细径薄壁管材，并通过OM、XRD、SEM及拉伸试验对合金与相/组织相关的力学行为进行研究。结果表明：冷轧组织由β相和应力诱发马氏体（SIMα?）组成，表现出强烈的非线性弹性变形行为；单β相的退火组织具有与应力诱发马氏体相变相关的“双屈服”行为。冷轧组织中的SIMα?相及复杂的变形亚结构与其非线性弹性行为相关，而并没有给予塑性明显的贡献。尽管退火态组织经冷轧后塑性大幅降低，但两种组织均为韧性断裂，表明TLM合金较宽的塑性调控范围使其具有深度冷变形加工的潜力。

Abstract:

Near β-type TLM titanium alloy tubes with small diameter and thin wall were fabricated by a combination of cold rolling and intermidate anneal. The mechanical behaviors related to the phases and microstructures were studied using optical metallography (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and tensile tests. The results show that the cold-rolled microstrcutre composed of β phase and stress induced martensite (SIMα?) exhibits obvious non-linear elastic deformation behavior, while the annealed single β phase displays the “double-yielding” associated with stress-induced martensitic phase transformation. Present authors consider that the non-linear elasticity has certain dependence on both of SIMα? and complicated sub-structures induced by the cold deformation, but both of which make an unconspicuous contribution to the plasticity. Although the elongation decreases after the cold rolling, the cold rolled microstructure still shows the ductile fracture mode similar with that of annealed specimens, which indicates that wider plasticity range of present TLM alloy supplys a tremendous potential in its deep cold deformation.