熊代玉,黎瑞敏,肖文娅,等.盐雾环境下AA2099铝锂合金腐蚀疲劳损伤行为研究[J].精密成形工程,2024,16(12):143-152.
XIONG Daiyu,LI Ruimin,XIAO Wenya,et al.Corrosion Fatigue Damage Behaviour of AA2099 Al-Li Alloy under Salt Spray Environment[J].Journal of Netshape Forming Engineering,2024,16(12):143-152. |
| 盐雾环境下AA2099铝锂合金腐蚀疲劳损伤行为研究 |
| Corrosion Fatigue Damage Behaviour of AA2099 Al-Li Alloy under Salt Spray Environment |
| 投稿时间：2024-04-01 |
| DOI：10.3969/j.issn.1674-6457.2024.12.012 |
| 中文关键词: 铝锂合金 微观组织 盐雾环境 腐蚀疲劳 断口形貌 |
| 英文关键词: Al-Li alloy microstructure salt spray environment corrosion fatigue fracture morphology |
| 基金项目:重庆市教育委员会科学技术研究项目(KJZD-K202301304);重庆市技术创新与应用发展专项重点项目(CSTB2022TIAD-KPX0073);重庆市自然科学基金(cstc2021jcyj-msxmX0960) |
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| 中文摘要: |
| 目的 研究盐雾环境下峰时效及过时效AA2099合金的腐蚀疲劳断裂行为，探明不同应变幅下腐蚀疲劳裂纹萌生及扩展的主导影响因素。方法 使用透射电镜分析不同时效状态试样的微观组织形貌;在3.5%(质量分数)NaCl盐雾环境下对铝锂合金进行不同应变幅条件的疲劳实验，并通过扫描电镜、能谱观察试样微观断口形貌。结果 在盐雾环境下，2种时效状态试样的裂纹萌生及扩展区域的断口表面均形成了腐蚀孔洞、腐蚀坑和腐蚀产物。当应变幅较高时，盐雾环境主要通过形成腐蚀坑促进裂纹形成的方式影响疲劳断裂行为。当应变幅较低时，前期扩展区表面形成大量腐蚀坑，此时腐蚀因素起主导作用;而在后期扩展和断裂区，腐蚀坑较少，以疲劳形貌特征为主，此时疲劳因素占主导地位。在静态盐雾腐蚀环境下，过时效状态试样发生点蚀现象，而在腐蚀疲劳过程中，盐雾环境反而加剧了晶间腐蚀现象。在峰值时效状态下，晶界析出相间距和晶界无析出带(PFZ)宽度均明显低于过时效态下的，部分瞬断区存在脆性沿晶断裂。在过时效状态下，晶界析出相间距中位数显著增加至113 nm，PFZ宽度最低值增加至75 nm，PFZ宽化和晶界析出相间距的增加导致晶界韧窝形成，瞬断区出现沿晶韧窝断裂特征。结论 盐雾环境促进裂纹萌生及扩展区域形成腐蚀孔洞、腐蚀坑和腐蚀产物，并随应变幅增加，腐蚀程度逐渐减轻。 |
| 英文摘要: |
| The work aims to study the corrosion fatigue fracture behavior of peak-aged and over-aged AA2099 alloys in salt spray environment, elucidating the dominant affecting factors on corrosion fatigue crack initiation and propagation under different strain amplitudes. The microstructure morphology of the specimens in different aging states was characterized by transmission electron microscopy. Fatigue tests were conducted on Al-Li alloys under varying strain amplitudes in a 3.5% NaCl salt spray environment. The fatigue fracture morphology of the specimens was characterized by scanning electron microscopy and energy spectroscopy. In the salt spray environment, corrosion features such as holes, pits, and corrosion products were observed on fracture surfaces within the crack initiation and propagation regions for specimens in two aging states. At high strain amplitudes, the salt spray environment primarily affected fatigue fracture behavior by promoting crack formation through the creation of corrosion pits. At low strain amplitudes, a significant quantity of corrosion pits appeared on the surface within the early-stage propagation region, during which the corrosion factor predominated. Whereas in the late-stage propagation and fracture region, there was a reduced presence of corrosion pits. Here, fatigue morphology was primarily characterized, with the fatigue factor predominating. In the static salt spray corrosion environment, pitting corrosion was prevalent in the over-aged specimen, while during corrosion fatigue, the salt spray environment exacerbated intergranular corrosion phenomena. In the peak-aged state, both the median of the grain boundary precipitate spacing and the width of the grain boundary precipitation-free zone (PFZ) were significantly lower compared to those in the over-aged state, with certain final fracture regions exhibiting brittle intergranular fracture. In the over-aged state, the median of the grain boundary precipitate spacing notably increased to 113 nm, with the minimum PFZ width reaching 75 nm. The broadening of the PFZ and the increase in grain boundary precipitate spacing facilitated the development of grain boundary toughness nests, leading to transgranular ductile fracture within the final fracture region. The salt spray environment accelerates the formation of corrosion features such as holes, pits, and corrosion products in the crack initiation and propagation regions, with corrosion severity diminishing as strain amplitude increases. |
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