作者：刘宸汗1, 刘玉1, 詹敏2, 汤栋1, 王硕1, 何超3, 王清远1,3
作者单位：1. 成都大学机械工程学院, 四川 成都 610106;
2. 成都大学建筑与土木工程学院, 四川 成都 610109;
3. 四川大学 深地科学与工程教育部重点实验室, 四川 成都 610065
关键词：镁合金;长寿命疲劳;裂纹萌生;裂纹扩展;应力强度因子
摘要：
镁合金作为结构材料在汽车、航空、航天等领域有广泛的应用前景，在实际服役过程中存在高频振动荷载的长期作用。为解决镁合金结构件在长寿命服役条件下的安全与可靠性问题，基于旋转弯曲和超声振动加载两种疲劳实验方法，研究WE94镁合金在高周与超高周区间（104~109周次）的疲劳强度与失效机制。结果表明，疲劳裂纹萌生于沿基面的滑移带并在断裂面上形成解理状“小平面”形貌；而在疲劳小裂纹扩展初期，裂纹面存在大量细小平行状条带，该条带于裂纹尖端与孪晶带的交互作用过程中形成。因此，镁合金疲劳小裂纹的萌生与扩展过程对材料局部微结构形态与变形机制表现出密切的相关性。
Study on initiation and propagation behavior of small cracks in long-life fatigue of WE94 magnesium alloy
LIU Chenhan1, LIU Yu1, ZHAN Min2, TANG Dong1, WANG Shuo1, HE Chao3, WANG Qingyuan1,3
1. School of Mechanical Engineering, Chengdu University, Chengdu 610106, China;
2. Architectural and Civil Engineering College of Chengdu University, Chengdu 610109, China;
3. Key Laboratory of Deep Earth Science and Engineering(Sichuan University), Ministry of Education, Chengdu 610065, China
Abstract: As a structural material, magnesium alloy has a wide application prospect in the fields of automobile, aviation, aerospace and so on. There is a long-term effect of high-frequency vibration load in the actual service process. In order to solve the safety and reliability problems of magnesium alloy structural parts under the condition of long-life service. Based on rotary bending and ultrasonic vibration loading, the fatigue strength and failure mechanism of WE94 magnesium alloy in high cycle and ultra-high cycle range (104-109 cycles) were studied. The results show that the fatigue crack originates from the slip band along the base plane and forms a cleavage “small plane” shape on the fracture surface. At the initial stage of fatigue small crack propagation, there are a large number of small parallel bands on the crack surface, which are formed during the interaction between the crack tip and the twin band. Therefore, the initiation and propagation of small fatigue cracks in magnesium alloys are closely related to the local microstructure and deformation mechanism.
Keywords: magnesium alloy;very high cycle fatigue;crack initiation;crack propagation;stress intensity factor
2023, 49(6):8-15,48 收稿日期: 2021-06-17;收到修改稿日期: 2021-08-23
基金项目: 国家自然科学基金资助项目(11832007)
作者简介: 刘宸汗(1997-),男,四川德阳市人,硕士研究生,专业方向为镁合金的超高周疲劳行为研究
参考文献
[1] HONG Y S, ZHAO A G, QIAN G A. Essential characteristics and influential factors for very-high-cycle fatigue behavior ofmetallic materials[J]. Acta Metallurgica Sinica, 2009, 45: 769-780
[2] HONG Y S, SUN C Q. The nature and the mechanism of crack initiation and early growth for very-high-cycle fatigue of metallic materials – an overview[J]. Theoretical and Applied Fracture Mechanics, 2017, 92: 331-50
[3] WANG Q Y, BATHIAS C, KAWAGOISHI N, et al. Effect of inclusion on subsurface crack initiation and gigacycle fatigue strength[J]. International Journal of Fatigue, 2002, 24(12): 1269-1274
[4] KARRA U, STICHB A, MAYER A. Very high cycle fatigue of wrought magnesium alloy AZ61[J]. ScienceDirect, 2016, 2: 1047-1054
[5] PAPAKYRIACOU M, MAYER H, FUCHS U, et al. Influence of atmospheric moisture on slow fatigue crack growth at ultrasonic frequency in aluminium and magnesium alloys[J]. Fatigue & Fracture of Engineering Materials & Structures, 2002, 25: 795-804
[6] NOVÝ F, JANEČEK M, ŠKORÍK V, et al. Very high cycle fatigue behaviour of as-extruded AZ31, AZ80, and ZK60 magnesium alloys[J]. International Journal of Materials Research, 2009, 100: 288-291
[7] ADAMS J F, ALLISON J E, JONES J W. The effects of heat treatment on very high cycle fatigue behavior in hot-rolled WE43 magnesium[J]. International Journal of Fatigue, 2016, 93: 372-386
[8] LIU W, DONG J, ZHANG P, et al. High cycle fatigue behavior of as-extruded ZK60 magnesium alloy[J]. Journal of Materials Science, 2009, 44: 2916
[9] SAKAI T, LIAN B, TAKEDA M, et al. Statistical duplex S–N characteristics of high carbon chromium bearing steel in rotating bending in very high cycle regime[J]. International Journal of Fatigue, 2010, 32: 497-504
[10] HE C, WU Y J, PENG L M, et al. Effect of microstructure on small fatigue crack initiation and early propagation behavior in Mg-10Gd-3Y-0.3Zr alloy[J]. International Journal of Fatigue, 2019, 119: 311-9
[11] UEMATSU Y, KAKIUCHI T, TAMADA K, et al. EBSD analysis of fatigue crack initiation behavior in coarse-grained AZ31 magnesium alloy[J]. International Journal of Fatigue, 2016, 84: 1-8
[12] YANG F, YIN S, LI S, et al. Crack initiation mechanism of extruded AZ31 magnesium alloy in the very high cycle fatigue regime[J]. Materials Science & Engineering A, 2008, 491: 131-136
[13] HUANG Z Y, LIU H Q, WANG H M, et al. Effect of stress ratio on VHCF behavior for a compressor blade titanium alloy[J]. International Journal of Fatigue, 2016, 93: 232-237
[14] NIKITIN A, PALIN-LUC T, SHANYAVSKIY A. Crack initiation in VHCF regime on forged titanium alloy under tensile and torsion loading modes[J]. International Journal of Fatigue, 2016, 93: 318-325
[15] OCHI Y, MATSUMURA T, MASAKI K, et al. High-cycle rotating bending fatigue property in very long-life regime of high-strength steels[J]. Fatigue & Fracture of Engineering Materials & Structures, 2002, 25: 823-830
[16] WU L, JAIN A, BROWN D, et al. Twinning–detwinning behavior during the strain- controlled low-cycle fatigue testing of a wrought magnesium alloy, ZK60A[J]. Acta Materialia, 2008, 56: 688-695
[17] KRUPP U, GIERTLER A, SÖKER M, et al. The behavior of short fatigue cracks during very high cycle (VHCF) fatigue of duplex stainless steel[J]. Engineering Fracture Mechanics, 2015, 145: 197-209
[18] ISTOMIN K, DÖNGES B, SCHELL N, et al. Analysis of VHCF damage in a duplex stainless steel using hard X-ray diffraction techniques[J]. International Journal of Fatigue, 2014, 66: 177-182
[19] MURAKAMI Y, USUKI H. Quantitative evaluation of effects of non-metallic inclusions on fatigue strength of high strength steels. II: Fatigue limit evaluation based on statistics for extreme values of inclusion size[J]. International Journal of Fatigue, 1989, 11: 299-307
[20] LI Y D, ZHANG L L, FEI Y H, et al. On the formation mechanisms of fine granular area (FGA) on the fracture surface for high strength steels in the VHCF regime[J]. International Journal of Fatigue, 2016, 82: 402-410
[21] CHEN Y, HE C, LIU F L, et al. Effect of microstructure inhomogeneity and crack initiation environment on the very high cycle fatigue behavior of a magnesium alloy[J]. International Journal of Fatigue, 2020, 131: 105-376
[22] SPRIESTERSBACH D, GRAD P, KERSCHER E. Influence of different non-metallic inclusion types on the crack initiation in high-strength steels in the VHCF regime[J]. International Journal of Fatigue, 2014, 64: 114-120
[23] MURAKAMI Y, ENDO M. Effects of defects, inclusions and inhomogeneities on fatigue strength[J]. International Journal of Fatigue, 1994, 16: 163-182
[24] ZHU M L, JIN L, XUAN F Z. Fatigue life and mechanistic modeling of interior microdefect induced cracking in high cycle and very high cycle regimes[J]. Acta Materialia, 2018, 157: 259-75
[25] CHAPETTI M, TAGAWA T, MIYATA T. Ultra-long cycle fatigue of high-strength carbon steels part II: estimation of fatigue limit for failure from internal inclusions[J]. Materials Science & Engineering A, 2003, 356: 236-244
[26] HONG Y, LEI Z, SUN C, et al. Propensities of crack interior initiation and early growth for very-high-cycle fatigue of high strength steels[J]. International Journal of Fatigue, 2014, 58: 144-151
[27] HONG Y S, LIU X L, LEI Z Q, et al. The formation mechanism of characteristic region at crack initiation for very-high cycle fatigue of high strength steels[J]. International Journal of Fatigue, 2016, 38(1): 108-118
