组成相中微观应力和应变对钛合金力学性能的贡献

Contribution of microscopic stress and strain in constituent phases to mechanical properties of titanium alloys

摘要:

分析组成相对钛合金力学性能的贡献对组织设计极为重要。通过真实组织有限元模型定量分析了α<sub>p</sub>和β<sub>t</sub>中的应力和应变,并确定了他们对Ti-6Al-2Zr-1Mo-1V钛合金强度和韧性的贡献。结果表明,α<sub>p</sub>和β<sub>t</sub>中的应力呈现正态分布。β<sub>t</sub>的峰值应力和应力峰高远大于α<sub>p</sub>。然而,α<sub>p</sub>具有较大的峰值应变,β<sub>t</sub>具有较大的应变峰高。随着α<sub>p</sub>体积分数从49%降低到12%,β<sub>t</sub>对抗拉强度的贡献从59%增加到92%,对失效应变的贡献从36%增加到75%。然而,随着β<sub>t</sub>贡献的增加,合金抗拉强度增加了17%,失效应变降低了21%。研究结果定量揭示了组成相对强度和韧性的贡献,为钛合金组织设计提供了基础。

Abstract:

Analysis the contribution of constituent phases to mechanical properties is critical to design the microstructure of titanium alloys. For this reason, the microscopic stress and strain in soft primary α (α<sub>p</sub>) and hard transformed β matrix (β<sub>t</sub>) are quantitatively analyzed by a microstructure-based finite element model to determine their contributions to the strength and ductility of Ti-6Al-2Zr-1Mo-1V alloy. The results show that microscopic stress in both α<sub>p</sub> and β<sub>t</sub> shows a normal distribution. The peak stress and stress peak height of β<sub>t</sub> are much larger than that of α<sub>p</sub>. While, α<sub>p</sub> has large peak strain and β<sub>t</sub> has large strain peak height. As α<sub>p</sub> volume fraction decreases from 49% to 12%, the contribution of β<sub>t</sub> to ultimate tensile strength (UTS) and failure strain (FS) of the alloy increases from 59% to 91% and from 36% to 75%, respectively. However, as the contribution of β<sub>t</sub> increases, UTS of the alloy increases 17% and FS decreases 21%. This finding quantitatively reveals the contribution of constituent phases to strength and ductility and provides a basis to design the microstructure of titanium alloys.