紧固件用Ti6Al4V合金的显微组织和力学性能

Microstructure and mechanical properties of Ti6Al4V alloy wire for fastener application

用光学显微镜、扫描电镜、X射线衍射仪和力学性能试验机研究了固溶温度以及丝材尺寸规格对Ti6Al4V合金丝材显微组织、相结构和力学性能的影响,结果表明:不同固溶温度处理后水淬,Ti6Al4V合金丝材由初生α相和转变β组织组成,对于不同固溶温度,转变β组织组成物不同,在低温下,为亚稳β相,随着温度升高,逐渐变为亚稳β+α″马氏体相、亚稳β+α'相;不同固溶温度处理后的试样经540℃×6 h(AC)时效处理后亚稳相发生分解,合金全部由稳定的α+β相组成,合金强度显著提高;尺寸规格对Ti6Al4V合金丝材力学性能影响较大,受淬透性影响,尺寸越大强度越低。

Effect of solution temperature on microstructure, mechanical properties and phase transformation of Ti6A14V alloy wire for fastener application was investigated by OM, SEM, XRD and tensile tests. Size effect of the alloy wire was also examined. The results reveal that microstructure of Ti6A14V alloy consistes of primary aphase and transformed β when the alloy is quenched from different temperatures. The transformed β constituent is metastable β phase when quenched from lower temperature, and is composed of metastable βphase and amartensite or metastable β phase and a martensite with solution temperature increasing. The metastable phases are decomposed and transformed to stablea phase and β phase after aging at 540 ℃ for 6 h, and the strength of the alloy is distinctly enhanced. Diameter of the alloy wire has an important influence on strength of Ti6AI4V alloy, the larger the alloy diameter is, the lower the strength is.