摘要
目的延长2A97铝锂合金的服役寿命,提高其耐腐蚀性能。方法采用正交试验法,研究喷丸工艺对合金2A97加工表面完整性的影响。通过极差分析,获得喷丸角度、弹丸粒径、喷丸速度和覆盖率等工艺参数对表面粗糙度、残余应力和加工硬化的影响。采用超景深三维显微镜分析2A97喷丸前后的表面形貌,采用扫描电子显微镜分析表面元素分布,采用光学显微镜表征其微观组织结构。通过动电位极化测试和表面接触角的测量,对比、评价喷丸处理对合金表面耐腐蚀性能的影响。结果喷丸处理在合金2A97表面引入了剧烈的塑性变形层,且使其表面粗糙化。与喷丸角度和覆盖率相比,喷丸速度和弹丸粒径对表面粗糙度的影响程度更大。喷丸表面的最大残余压应力为-415.54MPa,表面加工硬化程度在133%~241%之间波动。与未喷丸相比,经喷丸后试样表层组织发生了明显细化。在质量分数为3.5%的NaCl溶液中,喷丸试样表面表现出更好的耐腐蚀性能,表面腐蚀坑数量及大小明显降低;喷丸表面接触角均大于90°,均表现出疏水性。结论相较于铣削表面,2A97铝锂合金喷丸表面的耐腐蚀性能更加优异。
Due to the strong activity of Li element metal,Al-Li alloy is more vulnerable to the corrosion of harsh external environment,which shortens the service life and seriously restricts the popularization and application of this kind of material.Aiming at this problem,the work aims to investigate the effect of shot peening on the surface integrity and corrosion resistance of 2A97 Al-Li alloy.The effect of shot peening on machined surface integrity of Al-Li alloy was studied by orthogonal test.The influence of shot peening parameters,such as peening angle,shot diameter,peening speed and coverage,on the surface roughness,work hardening and residual stress was found out by range analysis,and the microstructure change was analyzed.The surface morphology of 2A97 before and after shot peening was analyzed by super depth of field three-dimensional microscope,the surface element distribution was analyzed by scanning electron microscope,and the microstructure was characterized by optical microscope.The effect of shot peening on the corrosion resistance of the alloy was compared and evaluated by electrochemical workstation and contact angle measuring instrument.The results showed that shot peening could cause severe plastic deformation in the surface layer of the sample,which increased the surface roughness,and led to surface defects such as peeling and cracks.Compared with the milling surface,the mass fraction of oxygen on the shot peening surface was 21.17%,which was more likely to form an oxide film.Shot peening impact angle and coverage had greater influence on the machined surface roughness than shot velocity and shot size.When the impact angle of the projectile was 45°,the surface of the material was corrugated due to the ploughing force.At the same time,work hardening and large surface residual compressive stress were introduced to the surface,the degree of work hardening fluctuated between 133%and 241%,the maximum work hardening layer depth was up to 250μm,and the maximum surface residual compressive stress was-415.54 MPa.Coverage had the greatest influence on surface microhardness and residual stress.Compared with the sample without shot peening,the surface microstructure of the sample after shot peening was obviously refined.The microstructure of the surface layer consisted of a severe plastic deformation layer near the peened surface and a grain refinement layer within 200μm from the peened surface.In 3.5%NaCl solution,the shot peening sample had better corrosion resistance,and the number and size of corrosion pits on the surface were significantly reduced.When the shot peening impact angle was 60°,the shot size was 0.8 mm,the shot velocity was 60 m/s and the coverage was 200%,the optimal processing parameters of improving the surface corrosion resistance by shot peening were obtained.Under this test condition,the corrosion potential of the workpiece was-1.0992 V,which was much higher than that of the milling surface.After shot peening,the contact angle of the alloy surface was greater than 90°,and the alloy surface showed hydrophobic characteristics.Compared with the milling surface,the shot peening surface of 2A97 Al-Li alloy has better corrosion resistance.
作者
黄浩
牛金涛
尹建国
张朝阳
王相宇
乔阳
HUANG Hao;NIU Jintao;YIN Jianguo;ZHANG Chaoyang;WANG Xiangyu;QIAO Yang(School of Mechanical Engineering,University of Jinan,Jinan 250022,China;Shandong Kaitai Shot Blasting Machinery Co.,Ltd.,Shandong Binzhou 256217,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第15期184-193,共10页
Surface Technology
基金
国家自然科学基金(52005215)
山东省自然科学基金(ZR2023ME077)
济南大学科技计划(XBS2015)。
作者简介
通信作者:牛金涛。;通信作者:乔阳。
