CAS OpenIR  > 研究所(批量导入)
中高碳合金钢高温防脱碳涂层制备及其机理研究
Alternative TitlePreparation and Mechanism of Decarburization Resistant Coating for Reheating of Medium and High Carb
王晓婧
Subtype博士
Thesis Advisor叶树峰
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
Keyword暂时性涂层   中高碳合金钢   防脱碳性能   高温钢坯
Abstract加热过程中,炉内氧化性气氛与中高碳钢基体表层中的碳相互作用,形成碳的气态氧化物而逃逸,造成脱碳。脱碳层比基体软,易变形,易形成裂缝,从而导致钢材抗拉强度和屈服极限下降,降低工件质量,影响钢材性能和使用寿命。而目前,控制脱碳主要是通过上游严格控制加热过程的升温制度和下游通过磨光、车削修磨等机械手段去除脱碳层,该方法会造成1%-5%的钢材损失,同时加大了生产工艺强度。针对中高碳合金钢易脱碳的特点,研究能够在钢坯加热过程中进行脱碳防护的涂层材料具有重大的应用意义和市场前景。本文在研究中高碳合金钢高温脱碳过程的基础上,根据不同钢材特点和升温制度,制备了用于热轧加热炉内不同种类中高碳合金钢用防脱碳涂层材料,使其在钢坯近表面微区形成C、O元素互扩散涂层屏障,系统研究涂层制备、防脱碳性能及防脱碳机制等。具体研究结果如下: 研究了以非调质钢49MnVS3、弹簧钢60Si2Mn和轴承钢GCr15为代表的易脱碳中高碳合金钢的高温脱碳行为,分析了不同种类的中高碳合金钢在不同热处理工艺下的脱碳层金相组织。实验证明了脱碳层深度和保温时间、加热温度、钢中碳含量、钢中其它合金元素及气氛的关系。 提出了中高碳合金钢高温防脱碳涂层的设计原则,分别从钢坯加热制度、钢材成分、膨胀系数和润湿性的角度分析涂层的选择方法。通过大量实验研究和分析,确定了针对轴承钢GCr15、弹簧钢60Si2Mn和非调质钢49MnVS3的防脱碳涂层体系。 分析了温度对轴承钢GCr15、弹簧钢60Si2Mn和非调质钢49MnVS3高温涂层防护效果的影响。针对GCr15的高温Al2O3?SiO2?MgO?CaO防护涂料,防护效果从1150℃开始提高,1250℃下保温30min防护效果可达到100%。针对60Si2Mn的高温Al2O3?SiO2?Na2O?P2O5防护涂料的防护转折点在1050℃,1100℃下恒温90min涂层能够100%去除脱碳层。而针对49MnVS3的Al2O3?SiO2?SiC涂层的防护效果从1100℃开始提高,在1200℃下60min可以达到100%去除脱碳层。 分析了保温时间对轴承钢GCr15、弹簧钢60Si2Mn和非调质钢49MnVS3高温涂层防护效果的影响。Al2O3?SiO2?MgO?CaO、Al2O3?SiO2?Na2O?P2O5和Al2O3?SiO2?SiC三种防脱碳涂层都是在更长保温时间下可达到更高的防护效果。 考察了炉内气氛对轴承钢GCr15高温涂层防护效果的影响。气氛中O2含量较高时,涂层的防护效果更明显;H2O含量较高时,涂层的防脱碳效果变差;防护效果最差的是在CO2含量比较高的气氛中。通过分析涂层厚度对弹簧钢60Si2Mn高温涂层防护效果的影响,确定了涂层厚度应该控制在200μm~350μm。通过考察冷却方式对弹簧钢60Si2Mn高温涂层防护效果的影响,证明了冷却速率越小,高温扩散作用时间越长,试样的脱碳越严重。 探讨了高温防脱碳涂层的作用机理。Al2O3?SiO2?MgO?CaO涂层在高温下生成的新烧结相—尖晶石(MgCr2O4, (Mg, Fe) (Cr, Al)2O4, MgAl2O4 和 Fe (Cr, Al)2O4)能够减小氧的扩散速率。Al2O3?SiO2?Na2O?P2O5涂层在高温烧结过程中形成新相(Na2Al6P2O15),通过固、液两相间的润湿和表面张力填充孔隙,使得固相结合更紧密,因而能够阻挡高温下碳、氧的二次扩散,以及在高于1100℃下防止氧气与金属基体反应。因此涂层的防护机制不是简单的熔膜屏蔽作用,而是高温下的化学反应膜的协同作用。 Al2O3?SiO2?SiC涂层在1150℃下随着保温时间的延长,涂层材料、氧化铁皮和低于1150℃下生成的脱碳层能快速形成有效防护层。脱碳层逐渐被防护层中的非晶SiO2消耗,在涂层与基体界面生成Fe2SiO4层。中高碳合金钢防脱碳涂层机理模型为:通过涂层材料优先侵蚀初期脱碳表面,在低温环境下与贫碳表面新生成致密的复合铁氧化物,抑制碳氧互渗,当温度升高后涂层能够完全去除脱碳层,并防止后续脱碳层的形成。 通过钢铁企业现场工业试验证明了本文所述三种防脱碳涂层的适应性良好,轴承钢GCr15高温防脱碳涂层在兴澄特钢减少三种不同规格终端线材脱碳层达到了63.6%,59.8%和64.0%。涂层在邢钢减轻铁素体层99.25%,总脱碳层88.25%。在南钢的两次弹簧钢60Si2Mn试验表明涂层的防脱碳效果分别可以达到63.82%和67.64%。苏钢非调质钢49MnVS3工业试验中,涂层的防护效果可以达到69.11%。高温防脱碳涂层的工业试验结果良好,大规模的工业应用将对钢铁企业提高产品表面质量具有重要的意义。
Other AbstractThe carbon in the medium and high carbon alloy steels reacts with oxidizing atmosphere in the furnace during the heat treatment procedures. The forming and escaping of the carbon oxides result in decarburization of the steels. Decarburized layer is easy to deform and crack, which leads to the decline in tensile strength and yield. It also implies changes of mechanical properties and service life of steel. At present, it mainly depends on controlling heating process in the furnace and polishing the final product to reduce decarburization. However, the polishing method always results in 1%-5% loss of steel and complicates the production process. The research in decarburization resistant coating for the billet during heating process is very significant and has great market potential. Based on the study of the decarburization process of medium and high carbon alloy steels and the heating demand, the decarburization resistant coatings materials for reheating of different types of steels were prepared and investigated. The results are shown as follows: The decarburization behaviors of non-quenched and tempered steel 49MnVS3, spring steel 60Si2Mn and bearing steel GCr15 during high temperature have been investigated. The different types of metallographic structures of decarburization have been studied. The effects of holding time, heating temperature, lattice type, type of solid solution, concentration and atmosphere to decarburization have been proved by the experiments. Based on the design principal, the selection process has been analyzed according to the heating schedule, the steel composition, the thermal expansion coefficient and the wettability.
Pages129
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8285
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
王晓婧. 中高碳合金钢高温防脱碳涂层制备及其机理研究[D]. 中国科学院研究生院,2013.
Files in This Item:
File Name/Size DocType Version Access License
中高碳合金钢高温防脱碳涂层制备及其机理研(6336KB) 限制开放CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[王晓婧]'s Articles
Baidu academic
Similar articles in Baidu academic
[王晓婧]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[王晓婧]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.