车身焊接接头在海运环境中的腐蚀特性及防护措施研究

发布时间：2018-01-21 00:13

本文关键词： 焊接接头耐蚀性组织结构冷喷锌　出处：《广东工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着国内制造技术的进步,汽车、机车、高铁等行业的蓬勃发展,国产汽车、机车的出口量的逐渐增加。出口运输方式主要为海运和空运。海洋运输环境下,钢结构部件容易发生大面积的生锈问题,特别是焊接件的焊接接头,腐蚀后对机械性能、外观等都造成不良影响,因此,研究车身焊接件在海洋环境中的腐蚀行为及其防护方法具有重要的科学应用和工程应用价值。本文通过粗糙度、金相组织分析的方法分析了金相组织和表面形貌对腐蚀速度的影响,从微观角度探索焊接接头的腐蚀行为与规律；运用电化学方法测试了不同焊接工艺(CO2气体保护焊和埋弧焊)的样品以及不同焊接接头部位(焊缝、热影响区和母材)的腐蚀速率,分析和讨论了腐蚀速率不同的原因,从而得出两种焊接方法在3.5%NaCl溶液中的腐蚀规律,通过循环腐蚀试验测试了不同焊接方法以及不同焊接接头部位的腐蚀程度,进一步验证了电化学方法的测试结果；通过自然环境暴露实验、中性盐雾实验对样品常规包装防护方式,即PE袋密封包装、气相防锈袋以及改进后的新型包装防护方式——气相防锈袋+冷喷锌的防护效果进行对比研究,在宏观上观察焊接接头的腐蚀特点和规律。研究结果表明：1)Q235钢焊接接头相对母材呈阳极极性,因而具有更强的腐蚀倾向,体现在焊缝和热影响区相对母材具有更大的腐蚀速率；电化学试验表明两种焊接工艺下,焊缝的腐蚀电流最大,热影响区次之。2)30天盐雾实验后,PE袋密封包装防护下焊接件基材、焊缝都出现了腐蚀迹象,其中焊缝部位相对于基材锈蚀更加严重,气相防锈袋密封包装防护下焊接件基材基本上无锈蚀,焊缝部位出现轻微腐蚀,气相防锈袋+冷喷锌包装防护下焊接件基材以及焊缝部位都相对完好,未出现任何锈蚀迹象。3)常规的包装防护方式对焊接件母材有一定的保护作用,但是对焊接部位并不能起到很好的保护。而改进后的气相防锈袋+冷喷锌包装防护方式综合了气相防锈技术和冷喷锌的双重优势,对焊接件的基材、焊缝及热影响区均具有很好的保护效果,且不影响后续的喷涂和焊接工艺等,该组合型防护方式可有效应用到焊接件的海运包装防护中。
[Abstract]:With the development of domestic manufacturing technology, the booming development of automobile, locomotive, high-speed rail and other industries, the export volume of domestic cars and locomotives is gradually increasing. The main modes of export transportation are seaborne and airway. under the environment of ocean transportation. Steel structural parts are prone to rust in a large area, especially welded joints, corrosion on the mechanical properties, appearance and so on have a negative impact, so. It has important scientific and engineering application value to study the corrosion behavior and protection methods of body welding parts in marine environment. The influence of metallographic structure and surface morphology on the corrosion rate was analyzed by means of metallographic analysis, and the corrosion behavior and law of welded joints were explored from the microcosmic point of view. The corrosion rates of different welding processes, such as CO _ 2 gas shielded welding and submerged arc welding, and different welding joints (weld, heat affected zone and base metal) were measured by electrochemical method. The causes of different corrosion rates are analyzed and discussed, and the corrosion rules of two welding methods in 3.5 NaCl solution are obtained. The corrosion degree of different welding methods and welded joints was tested by cyclic corrosion test, and the results of electrochemical methods were further verified. Through the natural environment exposure test, neutral salt spray test to the sample conventional packaging protection, namely PE bag sealed packaging. The effect of cold spraying zinc on gas phase antirust bag and a new kind of packaging protection method, which was improved, was compared and studied. The corrosion characteristics and rules of welded joints were observed macroscopically. The results show that the welded joints of 1 / 1 / Q235 steel have anode polarity relative to the base metal, so they have a stronger corrosion tendency. The corrosion rate of weld and heat affected zone is higher than that of base metal. The electrochemical test showed that the corrosion current of the weld was the largest in the two welding processes, followed by the heat affected zone (HAZ) after 30 days of salt spray test. The weld section is more serious than the base material corrosion, the gas phase anti-rust bag seal packaging protection of the welding material is basically no rust, the weld site appears slight corrosion. The base material and weld position of welding parts are relatively intact under the protection of cold spray zinc packaging with gas phase antirust bag. There is no rusting sign. 3) the conventional packaging protection method has certain protective effect on the base metal of welding parts. But the welding position can not be protected well. The improved gas phase antirust bag cold spray zinc packaging protection method synthesizes the double advantages of gas phase antirust technology and cold spraying zinc, and it has good effect on the base material of welding parts. The welding seam and heat affected zone have good protective effect, and do not affect the subsequent spraying and welding process. The combined protection method can be effectively applied to the marine packaging protection of welding parts.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.82

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