胡俊,廖凯,罗鹏博,李立君,陈飞.喷丸对铝合金亚表面裂纹闭合修复的影响与试验[J].表面技术,2024,53(7):180-189.
HU Jun,LIAO Kai,LUO Pengbo,LI Lijun,CHEN Fei.Effect and Experiment of Shot Peening on Closure and Repair of Sub-surface Cracks in Aluminum Alloy[J].Surface Technology,2024,53(7):180-189 |
| 喷丸对铝合金亚表面裂纹闭合修复的影响与试验 |
| Effect and Experiment of Shot Peening on Closure and Repair of Sub-surface Cracks in Aluminum Alloy |
| 投稿时间：2023-04-07 修订日期：2023-08-08 |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.07.019 |
| 中文关键词: 喷丸 7075-T651铝合金 亚表面裂纹 裂纹闭合 裂纹修复 |
| 英文关键词:shot peening 7075-T651 aluminum alloy sub-surface crack crack closure crack repair |
| 基金项目:国家重点研发计划(2022YFD2202103);国家自然科学基金(51475483) |
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| Author | Institution |
| HU Jun | School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China |
| LIAO Kai | School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China |
| LUO Pengbo | School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China |
| LI Lijun | School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China |
| CHEN Fei | School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China |
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| 中文摘要: |
| 目的 研究喷丸修复7075-T651铝合金亚表面裂纹的愈合机理及修复效果。方法 建立材料亚表面裂纹在喷丸作用下的修复模型，运用Ansys进行数值模拟计算，并预测裂纹深度修复阈值;根据模型，利用线切割制造相应的裂纹，并对其进行喷丸修复，从残余应力、疲劳强度、微观结构等方面分析裂纹愈合的机理，并评估修复效果。结果 仿真结果表明，在弹丸直径D=0.5 mm、弹丸速度v=100 m/s时喷丸修复效果最佳，裂纹修复深度阈值为0.15 mm;裂纹修复区域的表面应力为非裂纹区域的83.17%，实验结果与仿真结果相符;在修复裂纹后，试件的疲劳强度可以达到完好试样的70.32%。剧烈的喷丸冲击使裂纹亚表面材料产生较大的微观形变热，有利于组织形变，促使裂纹两侧的晶粒组织形成闭合挤压，宏观上表现为压应力下组织的紧密闭合，这种闭合起到了修复裂纹的作用，整体上属于物理性修复，但仍无法完全消除裂纹对材料的消极影响。结论 喷丸通过压力作用对亚表面材料的裂纹进行闭合修复，使材料的疲劳强度得到恢复，这对于铝合金结构件裂纹的早期修复和应急性修复具有积极作用。 |
| 英文摘要: |
| The purpose of this study is to explore the healing mechanism and repair effect of shot peening on sub-surface cracks in 7075-T651 aluminum alloy. Numerical simulation and experimentation were combined to establish a simplified crack model and ANSYS was used to perform numerical simulation on shot peening repair of cracks to preliminarily verify the feasibility of shot peening repair of cracks. The main factors such as diameter and velocity of the shot during shot peening were considered, and the shot peening parameters were optimized. The experiment followed the simulated crack model and obtained uniform standard samples after 0.3 MPa shot peening pretreatment. Cracks with a width of 0.05 mm and depths of 0.10 mm, 0.15 mm, and 0.20 mm were created with a wire cutting machine, and the cracks were located at the chamfer of the sample. The optimized process according to the simulation results was used for shot peen repair of cracks, and the crack repair effect was analyzed and evaluated from residual stress, fatigue strength, and microstructure. For this research of crack model with a crack width of 0.05 mm and a depth of 0.15 mm, simulation results showed that the best shot peening repair effect was achieved with a shot diameter D=0.5 mm and a shot velocity v=100 m/s. The optimized shot peening process parameters in the simulation corresponded to an experimental shot peening pressure of 0.56 MPa, which was used to carry out experiments on repairing surface cracks in aluminum alloy by shot peening. The experiment showed that in terms of residual stress, X-ray diffraction was used to measure the residual stress in the crack area and non-crack area of the sample. After the crack repair experiment, the residual stress at the crack was 83.17% of that in the non-crack area, which was close to the simulation result of 81.97%. At the same time, the overall deviation between experiment and simulation residual stress was about 20 MPa, which was due to the fact that the experimental sample underwent 0.3 MPa shot peening pretreatment, but the change trend between experiment and simulation was the same, indicating that shot peening had a good effect on repairing cracks. In terms of fatigue strength, experiments showed that as crack depth increased, sample fatigue strength decreased and sample damage became more severe. For shot-peened samples, the ratio of fatigue strength between samples and standard samples without cracks could represent the degree of crack repair. Experiments showed that cracks with depths of 0.1 mm and 0.15 mm had similar repair effects at 71.18% and 70.32%, respectively; while cracks with depths of 0.20 mm had a repair degree of only 44.36%, indicating poor repair effect. Shot peening could largely repair surface cracks while also having the effect of strengthening materials to improve their fatigue strength. However, fatigue testing of samples showed that samples still broke along repaired cracks after shot peening repair, indicating that cracks after shot peening repair were still weak points for sample fatigue and that shot peening repair had limited effect. In terms of microstructure, metallographic microscope and scanning electron microscope were used to observe the morphology of repaired cracks in samples by shot peening. Microstructure studies showed that severe impact from shot peening caused sub-surface material around cracks to generate large micro-deformation heat conducive to deformation organization formation, promoting closure extrusion between grains on both sides of cracks at macro level manifested as tight closure under compressive stress organization. This closure played a role in repairing cracks overall belonging to physical repair but was still unable to completely eliminate negative impact from cracks on materials. The study shows that shot peening repairs sub-surface material cracks through pressure action, and restores the material fatigue strength was well. It has positive meaning for early repair and emergency repair for aluminum alloy structural components. |
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