酸碱盐腐蚀环境对典型钢铝材料力学行为的影响机制研究

发布时间：2018-06-24 12:40

本文选题：腐蚀 + 金属材料　；参考：《吉林大学》2017年硕士论文

【摘要】：日常生产生活中,金属材料及制品的腐蚀现象十分普遍,如厨房用具腐蚀、船体腐蚀、车辆外壳腐蚀、海洋钻井平台腐蚀等。作为金属材料的主要失效形式之一,自然环境中广泛存在着海水、大气、土壤等典型腐蚀形式,工业应用中酸、碱、盐等介质也是造成金属腐蚀的主要形式。中国工程院的统计数据显示,我国每年因材料腐蚀破坏导致的经济损失达4800亿元。另据英国海洋局调查数据,海洋平台因材料的腐蚀失效造成石油年均减产13%左右。显见,金属材料的腐蚀破坏不仅会造成重大的经济损失,还可能诱发灾难性事故。因此,研究腐蚀环境下金属材料的失效机理与性能弱化机制,对于评估金属材料及其制品的服役可靠性、使用寿命乃至改善和提高金属材料耐腐蚀特性,具有重要的学术意义和良好的应用前景。论文在对材料环境试验及相关领域国内外发展现状进行综述分析的基础上,面向腐蚀环境下材料力学行为测试的需求,提出通过模拟金属材料在工业介质中的腐蚀环境,对钢和铝等典型金属材料开展腐蚀环境下力学行为与损伤机制的试验研究。试验中以酸、碱、盐作为主要腐蚀介质,分别以不同溶剂、浓度和腐蚀时间作为试验参量,采用课题组研制的多载荷多物理场耦合材料微观力学性能原位测试仪器、对腐蚀前后的材料样品开展力学性能测试,并就试验结果分别作比对分析;结合有限元仿真分析、材料表面元素含量测定分析和显微形貌观察分析等手段,综合分析研究不同腐蚀环境对金属材料力学性能和失效行为的作用机制。论文就不同腐蚀介质浓度和不同腐蚀时间下得到的金属样件,分别开展了拉伸和弯曲性能测试分析,测定了拉伸和弯曲试验曲线,对腐蚀介质浓度和腐蚀时间对Q235钢和7075铝合金力学性能的影响进行了比较分析。发现:经过盐酸酸性腐蚀后Q235钢的屈服强度和抗拉强度有所下降,且随着腐蚀浓度或腐蚀时间的增加下降幅度增大;经过氢氧化钠碱性腐蚀后Q235钢的屈服强度和抗拉强度略有下降变化;经过氯化钠盐性腐蚀后Q235钢上述力学性能变化很小或基本没有变化。7075铝在经过盐酸酸性腐蚀和氢氧化钠碱性腐蚀后,材料屈服强度、抗拉强度、伸长率等力学性能也均产生明显下降的变化。通过比较分析,Q235钢的抗腐蚀能力要比7075铝抗腐蚀能力强一些,酸腐蚀与碱腐蚀相比,酸腐蚀对材料影响更大。论文通过对金属材料腐蚀后的材料表面进行微观结构观察和成分分析,发现金属材料钢经过盐酸酸性腐蚀和金属材料铝经过盐酸与氢氧化钠腐蚀后,腐蚀表面有不同深度的细小裂纹,腐蚀形貌不规则,酸性腐蚀程度相对较深。材料经过腐蚀后表面成分含量也有明显变化,表面主要成分铁或铝的相对含量降低,其它杂质相对含量升高,因腐蚀或氧化等原因表面氧元素的相对含量偏高。论文通过对金属材料钢和铝腐蚀前后进行多载荷力热偶合的力学性能试验,发现在预拉伸扭转试验中,当在弹性阶段进行预拉伸后,进行扭转试验时其扭转屈服强度、抗扭强度等力学性能有下降趋势,当在塑性阶段进行预拉伸扭转后,因材料发生冷作硬化现象,腐蚀后的上述力学性能变化现象较小。在预扭转拉伸试验中,当预扭转角度在塑性阶段时,也因材料冷作硬化现象,其腐蚀后的拉伸屈服强度和抗拉强度等力学性能比未腐蚀时改变略小。在热耦合试验中,由于材料受到温度软化效应的影响,腐蚀后材料上述力学性能变化较腐蚀之前有所增大。
[Abstract]:In daily production and life, corrosion of metal materials and products is very common, such as kitchen utensils corrosion, hull corrosion, vehicle hull corrosion, marine drilling platform corrosion, etc. as one of the main failure forms of metal materials, there are typical corrosion forms in natural environment, such as sea water, large gas, soil and so on, acid, alkali and salt in industrial application. Medium is also the main form of metal corrosion. Statistical data from the Chinese Academy of engineering showed that the economic loss caused by corrosion damage of materials reached 480 billion yuan a year in China. According to the survey data of the British Oceanic Bureau, the annual output of oil was reduced by about 13% due to corrosion failure of materials. It will cause serious economic losses and may induce catastrophic accidents. Therefore, it is of great academic significance and good importance to study the failure mechanism and Weakening Mechanism of metal materials under corrosive environment. It is of great academic significance and good importance to evaluate the service reliability of metal materials and their products, and to improve and improve the corrosion resistance of metal materials. On the basis of the review and analysis of the material environment test and the development status at home and abroad in the related fields, the paper puts forward the requirement of the mechanical behavior test under the corrosive environment, and puts forward the mechanical behavior and loss of the typical metal materials, such as steel and aluminum, by simulating the corrosion environment of the metal materials in the industrial medium. Experimental study on the mechanism of injury. In the experiment, acid, alkali and salt are used as the main corrosion medium. The test parameters are used in different solvents, concentration and corrosion time respectively. The mechanical properties of the multi load multi physical field coupling materials developed by the project group are used to test the mechanical properties of the materials before the corrosion, and the test knot is carried out. The effect mechanism of different corrosion environment on mechanical properties and failure behavior of metal materials was analyzed by means of finite element simulation analysis, determination analysis of element surface element content and microscopic morphology observation and analysis. The paper is the metal sample of different corrosion medium concentration and different corrosion time. The tensile and bending tests were carried out and the tensile and bending test curves were measured. The effects of corrosion medium concentration and corrosion time on the mechanical properties of Q235 steel and 7075 aluminum alloy were compared. It was found that after acid corrosion, the yield strength and tensile strength of Q235 steel decreased with the corrosion concentration or the corrosion concentration. The decrease of corrosion time increases and the yield strength and tensile strength of Q235 steel decrease slightly after alkaline corrosion of sodium hydroxide, and the mechanical properties of Q235 steel are very small or basically unchanged after sodium chloride corrosion. After acid corrosion and alkaline corrosion of sodium hydroxide, the yield strength of.7075 aluminum is strong. The corrosion resistance of Q235 steel is better than that of 7075 aluminum, and acid corrosion is more affected by acid corrosion than alkali corrosion. The microstructure of the material after corrosion of metal material is observed and formed. It is found that after acid corrosion of hydrochloric acid and corrosion of metal material aluminum through hydrochloric acid and sodium hydroxide, the corrosion surface has small cracks with different depths, the corrosion morphology is irregular and the acid corrosion degree is relatively deep. The surface composition content of the material after corrosion is also obviously changed, the main component of the surface is iron or aluminum. The relative content of the other impurities is higher for the decrease of the content and the relative content of the oxygen element on the surface due to corrosion or oxidation. Through the mechanical performance test of the multi load force thermal coupling before and after the corrosion of the metal steel and aluminum, the paper finds that in the pretension torsion test, the torsion test is carried out when the elastic phase is prestretched. The mechanical properties, such as torsion yield strength and torsion strength, have a downward trend. When the material is cold and hardened after the plastic stage is pre stretched and twisted, the change of mechanical properties is smaller after the corrosion. In the pre torsion tensile test, when the pre torsion angle is at the plastic stage, the corrosion is also hardened because of the material cold. The mechanical properties, such as tensile yield strength and tensile strength, are slightly smaller than that of non corrosion. In the thermal coupling test, the mechanical properties of the material after corrosion are increased as the material is affected by the temperature softening effect.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.3

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