热处理时间对激光选区成形TC4钛合金组织及力学性能的影响

doi:10.13251/j.issn.0254-6051.2022.09.003

摘要/Abstract

摘要： 采用光学显微镜、扫描电镜和电子万能试验机研究固溶时效工艺中时间参数对激光选区成形(SLM)TC4(Ti6Al4V)钛合金显微组织和力学性能的影响。结果表明,退火态的SLM成形TC4钛合金的显微组织主要由连续的晶界α相(α_GB)、网篮状α相和β转变组织组成。经固溶时效处理后,试样的显微组织均呈现为网篮组织。在固溶温度为920 ℃,时效工艺为550 ℃×3 h,空冷的条件下,随着固溶时间从2 h增加为6 h,初生α相粗化明显,部分α_P相的晶粒长度可达16 μm;片状α相也发生粗化,晶粒长度由5~15 μm增长至20~30 μm,连续的晶界α相(α_GB)变得不连续,晶粒宽度由2.7 μm增长为4.4μm;同时,组织中出现了尺寸较大的α集束。试样的强度由1045.2 MPa增加为1156.9 MPa,断后伸长率由13.6%降低为6.7%。在时效温度为550 ℃,固溶工艺为920 ℃×2 h,水淬的条件下,随着时效时间从3 h增加为8 h,β转变组织的占比增加,初生α相的长度由40~60 μm减少为30~40 μm,晶界处连续的α_GB相晶粒宽度由2.7 μm增长为4.5 μm;片状α相稍有粗化,而试样的力学性能变化不大。因此,对于SLM成形TC4钛合金而言,在920 ℃固溶温度及550 ℃时效温度下,改变固溶和时效时间参数难以获得双态组织,且对综合力学性能的提高无显著影响。

关键词: 激光选区成形, TC4钛合金, 固溶时效, 显微组织, 力学性能

Abstract: By using optical microscope, scanning electron microscope and electronic universal testing machine, effect of time of solution and aging treatment on microstructure and mechanical properties of TC4 (Ti6Al4V) alloy fabricated by selective laser melting (SLM) was investigated. The results show that the annealed SLM-fabricated TC4 alloy is mainly composed of continuous α_GB, basketweave α and transformed β phases. After solution and aging treatment, the microstructure of the specimens all presents as the morphology of basketweave. Under the condition of solution treatment at 920 ℃ and aging process of 550 ℃×3 h, air cooring, with the solution time increasing from 2 h to 6 h, the primary α phase(α_P) is significantly coarsened and the length of part α_P is up to 16 μm. The lamellar α phase is also coarsened and the length of lamellar α phase increases from 5-15 um to 20-30 um. The continuous α_GB phase becomes discontinuous and its width increases from 2.7 μm to 4.4 μm. Meanwhile, there is largersize α colony presented. The tensile strength increases from 1045.2 MPa to 1156.9 MPa, the elongation decreases from 13.6% to 6.7%. Under the condition of aging at 550 ℃ and the solution process of 920 ℃×2 h, WQ, with the aging time increasing from 3 h to 8 h, the fraction of transformed β phase increases. The length of α_P phase decreases from 40-60 μm to 30-40 μm. The α_GB phase is also continuous while its width increases from 2.7 μm to 4.5 μm. The lamellar α phase coarsens slightly. The tensile properties do not change remarkably. Therefore, it can be concluded that the duplex microstructure is difficult to obtain by changing time of solution and aging treatment at solution temperature of 920 ℃ and aging temperature of 550 ℃ for the SLM-fabricated TC4 alloy, and it has no beneficial effect on improving comprehensive mechanical properties.

Key words: selective laser melting, TC4 titanium alloy, solution and aging treatment, microstructure, mechanical properties

中图分类号:

TG146.2⁺3

高星, 张宁, 丁燕, 蒋波. 热处理时间对激光选区成形TC4钛合金组织及力学性能的影响[J]. 金属热处理, 2022, 47(9): 12-17.

Gao Xing, Zhang Ning, Ding Yan, Jiang Bo. Effect of heat treatment time on microstructure and mechanical properties of TC4 titanium alloy fabricated by selective laser melting[J]. Heat Treatment of Metals, 2022, 47(9): 12-17.

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