高载荷作用下Ti6242钛合金低周疲劳和保载疲劳损伤行为分析

张明达; 曹京霞; 隋楠; 周毅; 黄旭

doi:10.11868/j.issn.1005-5053.2018.000085

高载荷作用下Ti6242钛合金低周疲劳和保载疲劳损伤行为分析

doi: 10.11868/j.issn.1005-5053.2018.000085

中国航发北京航空材料研究院先进钛合金航空科技重点实验室，北京 100095

详细信息

通讯作者:
张明达（1987—），男，博士，工程师，主要从事新型钢铁材料和钛合金材料研究工作，（E-mail）15901022010@139.com

中图分类号: TG146.2+3
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- 被引次数: 0
出版历程
- 收稿日期: 2018-08-02
- 修回日期: 2018-10-23
- 网络出版日期: 2018-10-25
- 刊出日期: 2019-02-01

Fracture behavior of low cycle fatigue and dwell fatigue of Ti6242 titanium alloy under high load

Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys，AECC Beijing Institute of Aeronautical Materials，Beijing 100095, China

摘要

摘要: Ti6242作为一种力学性能优异的近α型钛合金，与其他近α和α+β型钛合金类似，在接近室温时表现出保载疲劳的特征。本研究借鉴钛合金保载疲劳敏感性随测试载荷提升而上升的变化规律，设计高载荷的低周疲劳和保载疲劳力学性能测试，结合微观组织观察、力学性能表征和断口分析，系统分析微观组织和高载荷作用下低周疲劳和保载疲劳损伤行为，建立微观组织与力学性能的联系，总结不同载荷条件下的断口特征与规律，评估高载荷测试条件下Ti6242钛合金保载疲劳敏感性，结果证明通过提高载荷来表征Ti6242钛合金的保载疲劳性能具有可行性。
- 钛合金 /
- 保载疲劳 /
- 高载荷 /
- 断口分析
Abstract: As one kind of near alpha titanium alloys with excellent mechanical properties, Ti6242 alloy always shows the" dwell fatigue”characteristic, which is similar to other near α or α+β titanium alloys, especially at near room temperature. In this study, the low cycle fatigue and dwell fatigue tests under high load were designed according to the law of dwell fatigue sensitivity rising with the increase of test load. Combining with microstructure observation, mechanical property characterization and failure fracture analysis, the relationship between the microstructure and fracture behavior under high load low cycle fatigue and dwell fatigue tests was analyzed systematically. By summarizing the characteristics of failure fracture under room temperature tensile, high load low cycle fatigue test and high load dwell fatigue test, also comparing the dwell fatigue sensitivity of the Ti6242 alloy in this study with other Ti6242 alloys and other titanium alloys under different loading conditions, it is proved that increasing the fatigue load is a feasible way to characterize the dwell fatigue sensitivity of Ti6242 alloy.
- Titanium /
- dwell fatigue /
- high load /
- fracture analysis

HTML全文

图 1 实验取样及疲劳测试情况说明　（a）试样取样位置；（b）低周疲劳三角波波形；（c）保载疲劳梯形波

Figure 1. Descriptions of testing specimen and fatigue testing load wave　（a）location and direction of testing specimens；（b）triangular load wave for low-cycle fatigue testing；（c）trapezoidal load wave for dwell fatigue testing

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图 2 Ti6242合金不同取样位置显微组织　（a）近表面；（b）次表面；（c）心部

Figure 2. Microstructure of Ti6242 alloy at different locations　（a）near surface；（b）middle；（c）center

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图 3 Ti6242合金不同取样位置显微组织统计分析　（a）初生α相相体积分数统计；（b）初生α相截面面积统计

Figure 3. Microstructure statistical analysis of Ti6242 alloy at different locations　（a）volume fraction of primary α phase；（b）section area of primary α phase

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图 4 Ti6242合金断口形貌　（a）室温拉伸宏观断口；（b）保载疲劳宏观断口；（c）室温拉伸微观断口；（d）保载疲劳微观断口

Figure 4. Fracture morphologies of Ti6242 alloy　（a）macroscopic fracture of room temperature tensile specimen；（b）macroscopic fracture of dwell fatigue specimen；（c）microscopic fracture of room temperature tensile specimen；（d）microscopic fracture of dwell fatigue specimen

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图 5 Ti6242合金高载荷条件下保载疲劳断口特征（931 MPa/室温/K_t = 1/R = 0/加载卸载各1 s，保载120 s）　（a）韧窝断口区域；（b）白亮特征区域；（c）韧窝特征；（d）小平面特征

Figure 5. Fracture features of Ti6242 alloy of dwell fatigue specimens under high load（931 MPa/ room temperature/K_t = 1/R = 0/loading time 1 s and unloading time 1 s, load holding time 120 s）　（a）dimple fracture area；（b）white bright area；（c）dimple characteristics；（d）small facet characteristics

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图 6 Ti6242合金不同载荷条件的疲劳条带特征　（a）低周疲劳试样疲劳条带（869 MPa/室温/K_t = 1/R = 0/f = 0.5 Hz/三角波）；（b）高载荷低周疲劳试样（931 MPa/室温/K_t = 1/R = 0/f = 0.5 Hz/三角波）；（c）高载荷保载疲劳试样（931 MPa/室温/K_t = 1/R = 0/加载卸载各1 s，保载120 s）

Figure 6. Fatigue striation characteristics of Ti6242 alloy under different load conditions　（a）low-cycle fatigue（869 MPa/room temperature/K_t = 1/R = 0/f = 0.5 Hz/triangle wave）；（b）low-cycle fatigue（931 MPa/ room temperature/K_t = 1/R = 0/f = 0.5 Hz/triangle wave）；（c）dwell fatigue（931 MPa/room temperature/K_t = 1/R = 0/loading time 1 s and unloading time 1 s，load holding time 120 s）

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图 7 多种钛合金保载疲劳敏感性统计^{[7, 10, 13, 15-18]}

Figure 7. Dwell fatigue sensitivity of titanium alloys ^{[7, 10, 13, 15-18]}

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表 1 Ti6242钛合金不同取样位置室温拉伸力学性能（平均值）

Table 1. Room temperature tensile properties of Ti6242 alloy at different locations（average values）

Location	Tensile strength/MPa	Yield strength/MPa	Elongation/%	Reduction of area/%
Near surface	971.0 ± 5.7	869.5 ± 14.8	16.6 ± 2.0	40.4 ± 2.3
Middle	980.0 ± 7.1	881.0 ± 12.7	18.0 ± 3.5	40.3 ± 1.0
Center	975.0 ± 7.1	881.0 ± 8.5	18.8 ± 0.4	38.5 ± 2.1

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表 2 Ti6242钛合金高载荷低周疲劳和保载疲劳失效周期及保载疲劳敏感性

Table 2. Low-cycle fatigue (N_{f, l}) and dwell fatigue (N_{f, d}) of Ti6242 alloy under high load and dwell fatigue sensitivity

Location	Load/MPa	N_{f, l}/cycle	Location	Load/MPa	N_{f, d}/cycle	N_{f, l}/N_{f, d}
Near surface	931	5116	Near surface	931	142	36.0
Middle	931	10663	Middle	931	424	25.1
Center	931	8631	Center	931	495	17.4

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