GH4169合金高溫疲勞裂紋擴展的微觀損傷機制

侯杰; 董建新; 姚志浩

doi:10.13374/j.issn2095-9389.2018.07.008

GH4169合金高溫疲勞裂紋擴展的微觀損傷機制

doi: 10.13374/j.issn2095-9389.2018.07.008

北京科技大學材料科學與工程學院, 北京 100083

基金項目:

國家自然科學基金資助項目(51371023)

詳細信息

中圖分類號: TG146.1
計量
- 文章訪問數: 948
- HTML全文瀏覽量: 375
- PDF下載量: 37
- 被引次數: 0
出版歷程
- 收稿日期: 2017-06-28

Microscopic damage mechanisms during fatigue crack propagation at high temperature in GH4169 superalloy

School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

摘要

摘要: 空氣環境對高溫合金在高溫下的損傷行為有顯著影響.為了研究標準熱處理態GH4169合金在高溫疲勞裂紋擴展過程中的微觀損傷機制,在空氣環境中進行650℃、初始應力強度因子幅ΔK=30 MPa·m^1/2和應力比R=0.05的低周疲勞裂紋擴展試驗.使用掃描電鏡(SEM)及能譜(EDS)對試樣的斷口、外表面和剖面進行觀察和分析.實驗結果表明:疲勞主裂紋以沿晶方式萌生并擴展,隨后沿晶二次裂紋出現,并且其數量和長度沿主裂紋方向逐漸增加,進入快速擴展階段后,斷口呈現韌窩組織形貌;在裂紋擴展過程中,δ相與基體的界面發生氧化,使得沿晶二次裂紋沿界面擴展并產生偏折,從而起到阻礙二次裂紋擴展的作用;試樣外表面的主裂紋周圍出現晶界氧化損傷區,其尺寸和晶界開裂程度沿主裂紋擴展方向逐漸增大.
- GH4169合金 /
- 高溫 /
- 裂紋擴展 /
- 晶界氧化 /
- δ相
Abstract: The air environment strongly influences the damage behaviors of superalloys at high temperatures. To investigate the microscopic damage mechanisms during high-temperature fatigue crack growth in standard heat-treated GH4169 superalloys, low-cycle-fatigue crack growth tests were conducted at 650℃ with initial stress intensity factor ΔK=30 MPa·m^1/2 and stress ratio R=0.05 under the air environment. The fracture surface, outside surface, and central sectioned surface of the specimen were observed and analyzed using scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The results show that the main fatigue crack initiates and propagates intergranularly, followed by the appearance of intergranular secondary cracks, whose quantity and length increase along the propagating direction of the main crack. In the rupture stage, a dimpled morphology appears on the fracture surface. Oxidation occurs at the interfaces between δ phases and the matrix during the fatigue crack propagation process, which leads to secondary cracks propagating along the interfaces. This leads to their inflection, which in turn retards their propagation. A grain-boundary oxidation damage zone exists at the outside surface of the specimen near the main crack. The size and degree of grain-boundary cracking increase along the propagating direction of the main crack.
- GH4169 superalloy /
- high temperature /
- crack propagation /
- grain boundary oxidation /
- δ phase

HTML全文

參考文獻(22)

[1]	Pollock T M. Alloy design for aircraft engines. Nat Mater, 2016, 15:809
[2]	Xu J H, Huang Z W, Jiang L. Effect of heat treatment on low cycle fatigue of IN718 superalloy at the elevated temperatures. Mater Sci Eng A, 2017, 690:137
[3]	Nemeth A A N, Crudden D J, Armstrong D E J, et al. Environmentally-assisted grain boundary attack as a mechanism of embrittlement in a nickel-based superalloy. Acta Mater, 2017, 126:361
[4]	Jiang R, Reed P A S. Critical assessment 21:oxygen-assisted fatigue crack propagation in turbine disc superalloys. Mater Sci Technol, 2016, 32(5):401
[5]	Anderson M, Thielin A L, Bridier F, et al. δ phase precipitation in Inconel 718 and associated mechanical properties. Mater Sci Eng A, 2017, 679:48
[6]	Silva C, Song M, Leonard K, et al. Characterization of alloy 718 subjected to different thermomechanical treatments. Mater Sci Eng A, 2017, 691:195
[7]	Valle L C M, Araujo L S, Gabriel S B, et al. The effect of δ phase on the mechanical properties of an Inconel 718 superalloy. J Mater Eng Perform, 2013, 22(5):1512
[8]	Tarzimoghadam Z, Rohwerder M, Merzlikin S V, et al. Multi-scale and partially resolved hydrogen mapping in a Ni-Nb model alloy reveals the role of the δ phase in hydrogen embrittlement of alloy 718. Acta Mater, 2016, 109:69
[9]	Jiang R, Bull D J, Proprentner D, et al. Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based superalloy:from 2D to 3D assessment. Int J Fatigue, 2017, 99:175
[10]	Cruchley S, Li H Y, Evans H E, et al. The role of oxidation damage in fatigue crack initiation of an advanced Ni-based superalloy. Int J Fatigue, 2015, 81:265
[11]	Osinkolu G A, Onofrio G, Marchionni M. Fatigue crack growth in polycrystalline IN718 superalloy. Mater Sci Eng A, 2003, 356(1-2):425
[12]	Smith H H, Michel D J. Effect of environment on fatigue crack propagation behavior of alloy 718 at elevated temperatures. Metall Trans A, 1986, 17:370
[13]	Evans H E, Li H Y, Bowen P. A mechanism for stress-aided grain boundary oxidation ahead of cracks. Scripta Mater, 2013, 69(2):179
[14]	Pfaendtner J A, McMahon C J. Oxygen-induced intergranular cracking of a Ni-base alloy at elevated temperatures-an example of dynamic embrittlement. Acta Mater, 2001, 49(16):3369
[15]	Chen Y Q, Pan S P, Zhou M Z, et al. Effects of inclusions, grain boundaries and grain orientations on the fatigue crack initiation and propagation behavior of 2524-T3 Al alloy. Mater Sci Eng A, 2013, 580:150
[16]	Foroozmehr F, Verreman Y, Chen J Q, et al. Effect of inclusions on fracture behavior of cast and wrought 13%Cr-4%Ni martensitic stainless steels. Eng Fract Mech, 2017, 175:262
[17]	An J L, Wang L, Liu Y, et al. The role of δ phase for fatigue crack propagation behavior in a Ni base superalloy at room temperature. Mater Sci Eng A, 2017, 684:312
[18]	Saarimaki J, Colliander M H, Moverare J J. Anisotropy effects during dwell-fatigue caused by δ-phase orientation in forged Inconel 718. Mater Sci Eng A, 2017, 692:174
[19]	Krupp U, Kane W M, Laird C, et al. Brittle intergranular fracture of a Ni-base superalloy at high temperatures by dynamic embrittlement. Mater Sci Eng A, 2004, 387-389:409
[20]	Boyd-Lee A D. Fatigue crack growth resistant microstructures in polycrystalline Ni-base superalloys for aeroengines. Int J Fatigue, 1999, 21(4):393
[21]	Jiang R, Everitt S, Lewandowski M, et al. Grain size effects in a Ni-based turbine disc alloy in the time and cycle dependent crack growth regimes. Int J Fatigue, 2014, 62:217
[22]	Connolley T, Reed P A S, Starink M J. Short crack initiation and growth at 600℃ in notched specimens of Inconel718. Mater Sci Eng A, 2003, 340(1-2):139