【作者】 李文；

【导师】 杜学铭； 吕奎清；

【作者基本信息】 武汉理工大学 ， 材料加工工程， 2010， 硕士

【摘要】 随着纳米技术和纳米材料的迅猛发展,学者们开始探讨纳米材料在焊接领域的研究和应用,到目前为止已有各种各样的纳米材料或纳米技术应用到焊接领域了。纳米技术与材料已经在焊接材料、焊接结构、焊接工艺、焊接保护等方面都开始了广泛的研究,然而纳米焊接材料现在都停留在特种焊接材料上,同时焊接材料的研究倾向性也使得普通焊材的发展受到一定的影响。而纳米材料或超细粉末对普通焊条的性能影响研究很少,目前尚无系统的理论。基于此,本文以武汉铁锚焊接材料股份有限公司成熟的E5003焊条配方为基础,改变其中金红石的粒径,研究金红石粒径对该焊条性能变化的规律和出现的问题。同时也研究纳米TiO2添加量对焊条性能的影响规律和出现的问题。研究这类材料的尺度对焊条的性能的影响,以丰富焊接材料研究的理论和研制的途径。在研究试验中,用行星式球磨机加工不同粒径的金红石,此类方法加工的粉是超细粉,纳米Ti02购买获得。试验设计中用不同球磨时间的金红石分别100%取代原配方中金红石,压制合格新焊条,进行试验。同时添加不同比例的Ti02取代金红石,压制合格新焊条,进行试验。利用扫描电镜计算不同球磨时间粉末的平均粒径,利用XRD衍射分析计算纳米TiO2的平均粒径。使用GX-高温物性仪测定焊条药皮的熔点,研究该类焊条药皮熔化特性。用汉偌威电弧质量分析仪分析焊条的电弧特性。按国家标准和自制试验平台评定焊条的性能,包括焊条的再引弧性,断弧长度,脱渣率,成型质量与飞溅,并测定焊条的熔化系数,熔敷效率。利用甘油法测定焊条的熔敷金属的扩散氢量。利用金相显微镜和扫描电镜观察焊缝组织和冲击式样断口形貌,利用这些微观结果分析其力学性能变化的本质问题。做熔敷金属冲击试验,拉伸试验,熔敷金属化学成分分析,全面研究焊条性能变化规律。研究表明,加入超细粉金红石,焊条外观质量较好,药皮结构变得更加致密,烘干过程可能会出现药皮破裂,外观颜色更和球磨后金红石颜色接近,焊条工艺性能、力学性能有明显变化。加入纳米TiO2,随纳米TiO2百分比的增加,焊条压制出现先好再困难的现象,药皮随纳米TiO2加入量增加,药皮变得更加致密和药皮颜色变白,药皮表面可能会出现褶皱,焊条工艺性能、力学性能有明显变化。焊条研究结果表明,以细化的金红石加入焊条药皮中可以改善焊条的力学性能,提高熔敷金属的冲击韧性,并随着金红石粒径的减小,这一提高趋势越明显,当尺寸达到一定范围时,金红石粒径的减小反而使得力学性能下降。该类焊条的工艺性能也出现规律性变化。研究还表明球磨24h的金红石添加到药皮中使得焊条性能最好。纳米Ti02可以改善焊条的力学性能,改变焊条的工艺性能,能提高熔敷金属的冲击韧性,研究表明添加50%的纳米Ti02性能最好。值得指出的是拉伸试验表明焊条的熔敷金属强度略有下降,但均在国标以内。更多还原

【Abstract】 With the rapid development of nano-technology and nano-materials, scholars began to explore the field of nano-materials in welding research and applications. So far a variety of nano-materials and nano-technology have been exploited into the field of welding. Nano- technology and materials have been extensively studied in welding materials, welding structures, welding technology, welding protection etc. But nowdays nano-welding materials are still stayed in the special welding materials, at the same time, the research tendency of welding materials have also made certain impact in the development of general welding materials. The ultra-fine powder or nano-materials in welding of the performance of ordinary coat electrodes little research is currently no systematic theory. Based on this, this paper use Wuhan TEMO welding material Co.,LTD’s mature E5003 coat electrodes-based formula, and change the particle size of rutile,to research how the rutile particle size and nano-TiO2 will affect the variation of the coat electrodes performance and the problems. We also study how the scale of such material will effect the coat electrodes performance, so as to enrich the theory of welding material and the development way.In the research trials, we use planetary ball milling to process different particle size of rutile powder and which is superfine powder. TiO2 is obtained by purchase. In the Experimental design, we use the rutile we made by different milling time to totally replace the original recipe,and then suppress new qualified coat electrodes to experiment and test their performance. At the same time,we add different proportions of TiO2 to replace rutile, and also suppress new qualified coat electrodes to experiment and test their performance. Scanning electron microscopy is used to calculate the average powder particle size with differet milling time, XRD diffraction analysis is used to calculate the average size of nano- TiO2. we use GX-temperature properties to measure the melting point of coated electrodes and study their melting characteristics of such electrodes coating. We use Hannover arc-quality analyzer to research the arc welding characteristics. According to national standard and self-assessment test platform, including the arc of the electrode, breaking arc length, slag rate, forming quality, spatter, the electrode melting coefficient of determination and deposition efficiency. And then glycerol to determine the diffusible hydrogen content of deposited metal. Optical microscopy and scanning electron microscope to observe the weld specimen fracture surface.These microscope analysis results are used to analysis the essence problems that why mechanical properties change. Deposited metal impact test, tensile test, deposited metal chemical composition analysis are used to comprehensively study the variation of coat electrodes performance.The studies show that when adding superfine powder of rutile, the coat electrodes quality appears better, coating structure becomes more dense, the coat maybe broken when drying, the appearance color is close to the milling retile, there are significant changes in mechanical properties. Adding nano-TiO2, with the increase of nano-TiO2 percentage, suppressing coat electrodes wil be change from easy to hard, with the percentage of nano-TiO2 changes, it will be white and the structures turn to be denser, the surface of coating may appear wrinkled, there are significant changes in the in mechanical properties of coat electrodes.The results show that when fine powder of rutile was added to the coat electrodes,it can improve the mechanical properties, improve the impact toughness of deposited metal, and then with the rutile particle size decreases, the increasing trend tend to be more obvious, when the size reaches a certain range, the decrease of particle size of rutile will decrease the mechanical performance. Such coat electrodes process performance will also appear regular variation.The study also showed that the rutile in the coat that milled 24h will acquire a best performance. Nano-TiO2 in new coated electrodes can improve the impact toughness of deposited metal, process performance, it also can improve the the mechanical properties. The research shows that adding 50% Nano-TiO2 in electrode coating is the best performance. It is worth noting that the tensile test show that the strength of deposited metal electrode decreased slightly, but all little more than the national standards.更多还原