文献类型：期刊文献

中文题名：深冷处理对7075-T6铝合金高速切削亚表层微细观演变及腐蚀机理的影响研究

英文题名：Effect of Cryogenic Treatment on Microstructural Evolution and Corrosion Mechanism in Subsurface Layer of 7075-T6 Aluminum Alloy during High-speed Machining

作者：岳修杰[1];张平[2];高业然[2];孙亚杰[2];王优强[1]

机构：[1]青岛理工大学机械与汽车工程学院,山东青岛266520;[2]广东海洋大学机电工程学院,广东湛江524088

年份：2024

卷号：53

期号：10

起止页码：134

中文期刊名：表面技术

外文期刊名：Surface Technology

收录：北大核心2023、CSTPCD、、EI(收录号：20242416251684)、Scopus、CSCD2023_2024、北大核心、CSCD

基金：国家自然科学基金(51705270);山东省自然科学基金(ZR2022QE149)。

语种：中文

中文关键词：7075-T6铝合金;深冷处理;微观组织;析出相;表面质量;电化学腐蚀

外文关键词：7075-T6 aluminum alloy;cryogenic treatment;microstructure;precipitated phase;surface quality;electrochemical corrosion

中文摘要：目的探究切削速度对经深冷处理和未经深冷处理的7075-T6铝合金微观组织演变机理和耐腐性的影响。方法选取经深冷处理(T6-C)和未经深冷处理(T6)的7075-T6铝合金进行切削加工,并在3.5%(质量分数)NaCl溶液中进行电化学腐蚀实验。通过透射电镜(TEM)、HRTEM、X射线衍射仪(XRD)、扫描电镜(SEM)和电化学分析,对微观组织演变、表面形貌和耐腐蚀性能进行研究。结果在相同的切削参数下,相较于T6铝合金,T6-C铝合金表现出更小的晶粒尺寸,铝基体中存在更多的析出相——η相MgZn2,且位错密度以及析出相密度更大,无析出晶界带为断续分布。深冷处理和增大切削速度都显著提高了7075-T6铝合金的耐腐蚀性能,且腐蚀形貌存在显著的龟裂现象。通过电化学分析得知,当切削速度为1500 m/min时,与未深冷处理相比,深冷处理后的7075-T6铝合金的电流密度减小了3.24×10^(-6)A/cm^(2),极化电阻增大了1.68×10^(5)?·cm^(2),在该参数下表现出较好的耐腐蚀性能。与此同时,随着切削速度的增大,容抗弧半径呈增大的变化趋势,且相较于T6铝合金,T6-C铝合金具有更大的容抗弧半径。结论深冷处理可以有效细化7075-T6铝合金的晶粒结构,进而强化位错密度,从而显著提升该合金的耐腐蚀性能。

外文摘要：In the realm of aviation and aerospace,7075 aluminum alloy has emerged as a pivotal choice for aircraft structural components,engine parts,and aerospace assemblies,owing to its remarkable attributes such as elevated strength and lightweight characteristics.However,confronted with intricate operational conditions,its components are often subject to elevated temperature,high pressure,and frequent load,rendering them susceptible to fractures and failures.Cryogenic treatment can enhance the dislocation density and crystalline structure of 7075 aluminum alloy,thereby bolstering its resistance to stress concentration and corrosion properties.In this paper,7075-T6 aluminum alloy was selected as the research object,and its microstructure evolution,surface morphology and corrosion resistance were investigated by transmission electron microscopy(TEM),HRTEM,X-ray diffractometry(XRD),scanning electron microscopy(SEM)and electrochemical analysis.The present investigation delved into the influence of cutting speed on the microstructural evolution mechanism and corrosion resistance properties of both cryogenically treated and untreated 7075-T6 aluminum alloy.The results showed that the surface defects of the workpiece at different cutting speeds were mainly characterized by chip adhesion and microcracks,and the surface quality of the workpiece was better when the cutting speed was increased to 1500 m/min compared with the cutting speed of 500 m/min.The surfaces of both T6 and T6-C aluminum alloys,after undergoing machining processes,were found to display the presence ofα-phase(Al matrix)andη-phase(MgZn2)upon examination.In terms of the diffraction intensity of theα-phase peaks,the T6 aluminum alloy exhibited its highest diffraction peak on the(200)crystal plane when the cutting speed was set at 500 m/min.After cutting of 7075-T6 aluminum alloy without deep-cooling treatment,the precipitation phase was dominated by bar and block morphology,which produced a grain boundary free zone(PFZ)with a width of about 12-20 nm.After the cutting of 7075-T6 aluminum alloy after deep-cooling treatment,the precipitation phase was dominated by a massive morphology,and there existed a discontinuous non-precipitated grain boundary band with a width of 9-17 nm.Combined with the corresponding diffraction pattern(SAED)and XRD analysis,it could be seen that the precipitated phase was mainlyη-MgZn2.Both the deep-cooling treatment and the increased cutting speed significantly improved the corrosion resistance of the 7075-T6 aluminum alloy,there was significant cracking in the corrosion morphology.Through electrochemical analysis,it was learned that at a cutting speed of 1500 m/min,the current density of the deep-cooled 7075-T6 aluminum alloy decreased by 3.24×10^(-6) A/cm^(2) and the polarization resistance increased by 1.68×10^(5)?·cm^(2) compared with that without deep-cooling treatment.At the same time,with the increase of cutting speed,the radius of the capacitive showed an increasing trend of change,and compared with T6 aluminum alloy,T6-C aluminum alloy had a larger radius of arc resistance on the surface.Deep-cooling treatment can effectively refine the grain structure of 7075-T6 aluminum alloy,which in turn strengthens the dislocation density and thus significantly improves the corrosion resistance of the alloy.