磨煤辊耐磨堆焊明弧自保护药芯焊丝的研究
发布时间：2018-11-18 17:50
【摘要】：磨煤辊是煤粉制备的重要设备,其耐磨性受到广泛关注。采用药芯焊丝明弧自保护堆焊修复或制造磨煤辊已成为一种经济且可靠的提高磨煤辊使用寿命的方法。本文以铁基高铬明弧堆焊合金为研究对象,通过调节药芯焊丝成分,试图研制能满足磨煤辊堆焊实际应用要求的自保护耐磨堆焊药芯焊丝。采用药芯焊丝自保护明弧焊方法在Q235A基体上制备堆焊合金,借助光学显微镜、扫描电子显微镜及其附属电子能谱仪、X射线衍射仪,观察分析其显微组织,并通过宏观硬度测试和湿砂磨粒磨损试验研究其性能。首先,研究了不同碳含量的过共晶高铬明弧堆焊合金的显微组织及性能,结果表明,高铬明弧堆焊合金组织由初生碳化物M7C3和共晶基体组成,随着合金中碳含量的增加,初生碳化物M7C3数量增多,尺寸变大,组织中碳化物体积分数显著增加,基体数量减少,共晶碳化物连续性增强对基体割裂作用加剧,致使合金韧性降低。碳含量对高铬明弧堆焊合金硬度及耐磨性影响显著,随着碳含量的增加,硬度升高,耐磨性反而下降。当碳含量较高时,微观剥落成为高铬堆焊合金耐磨性下降的主要原因,提高高铬堆焊合金的耐磨性应当注重其韧性的改善。其次,分别向药芯焊丝中加入不同含量的硼铁、钒铁、钨铁、钛铁和铌铁,研究了合金元素硼、钨、钒、钛和铌对高铬明弧堆焊合金组织和性能的影响。结果表明:硼能使共晶点左移,促进初生碳化物M7C3的生成,且组织中生成高硬度的硼化物或碳硼化合物,显著提高堆焊合金硬度,但过多的硼使合金脆性增加,耐磨性下降;钒对碳原子具有团聚效应,可改变熔体碳浓度分布,增加初生M7C3相体积分数,抑制脆性组织生成,适量V具有显著改善明弧堆焊合金耐磨性的作用;钨能使高铬合金共晶点左移,增加初生碳化物M7C3体积分数,减少共晶碳化物的数量,使基体组织中奥氏体增加,有利于合金韧性的提高;钛的加入使熔体优先析出TiC,TiC充当初生M7C3和γ-Fe的异质形核核心,提高它们的形核率,起到细化初生相和基体组织的作用,有利于合金韧性的提高,但过多的钛会使剩余熔体贫碳,反而抑制初生M7C3的生成;高铬合金中的铌全部以NbC的形式存在,NbC弥散分布,可以细化晶粒,增加合金韧性,对提高堆焊合金硬度和耐磨性有利。
[Abstract]:Grinding roller is an important equipment for the preparation of pulverized coal, and its wear resistance is widely concerned. It has become an economical and reliable method to improve the service life of grinding coal roller by using flux cored wire self-protection surfacing welding to repair or manufacture grinding coal roller. By adjusting the composition of flux-cored wire, a self-protective and wear-resistant surfacing flux-cored wire can be developed to meet the requirements of the practical application of the surfacing welding of grinding coal roll, taking the iron-base high-chromium bright arc surfacing alloy as the research object in this paper. The surfacing alloy was prepared on Q235A substrate by self-shielded open arc welding with flux-cored wire. The microstructure was observed and analyzed by means of optical microscope, scanning electron microscope and its subsidiary electron energy spectrometer, X-ray diffractometer. The properties were studied by macrohardness test and wet sand abrasive wear test. Firstly, the microstructure and properties of hypereutectic high chromium open arc surfacing alloy with different carbon content were studied. The results show that the microstructure of high chromium open arc surfacing alloy is composed of primary carbides M7C3 and eutectic matrix, and with the increase of carbon content in the alloy, The number and size of primary carbides M7C3 increased, the volume fraction of carbides in microstructure increased significantly, the number of matrix decreased, and the effect of eutectic carbide continuity on matrix cleavage increased, resulting in the decrease of alloy toughness. The effect of carbon content on hardness and wear resistance of high chromium bright arc surfacing alloy is significant. With the increase of carbon content, hardness increases and wear resistance decreases. When the carbon content is high, the micro-exfoliation becomes the main reason for the decrease of wear resistance of the high chromium surfacing alloy, and the improvement of the wear resistance of the high chromium surfacing alloy should pay attention to the improvement of its toughness. Secondly, the effects of the alloying elements boron, tungsten, vanadium, titanium and niobium on the microstructure and properties of high chromium bright arc surfacing alloys were studied by adding different amounts of ferric boron, ferrovanadium, tungsten, vanadium, titanium and niobium into the flux-cored wire respectively. The results show that boron can make the eutectic point shift to the left, promote the formation of primary carbides M7C3, and form high hardness boride or carboboron compounds in the microstructure, which can significantly increase the hardness of surfacing alloy, but excessive boron can increase the brittleness of the alloy and decrease its wear resistance. Vanadium has agglomeration effect on carbon atoms, which can change the carbon concentration distribution of melt, increase the volume fraction of primary M7C3 phase and inhibit the formation of brittle microstructure. Tungsten can make eutectic point of high chromium alloy move to the left, increase M7C3 volume fraction of primary carbides, reduce the amount of eutectic carbides, increase austenite in matrix structure, and improve the toughness of alloy. The addition of titanium makes the melt precipitate TiC,TiC as the heterogeneous nucleation core of primary M7C3 and 纬-Fe, increases their nucleation rate, refines the primary phase and matrix structure, and improves the toughness of the alloy. However, too much titanium can make the residual melt carbon poor and inhibit the formation of primary M7C3. All niobium in high chromium alloy exists in the form of NbC and NbC dispersion distribution can refine the grain and increase the toughness of the alloy. It is beneficial to improve the hardness and wear resistance of the surfacing alloy.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG422.3
本文编号：2340712
[Abstract]:Grinding roller is an important equipment for the preparation of pulverized coal, and its wear resistance is widely concerned. It has become an economical and reliable method to improve the service life of grinding coal roller by using flux cored wire self-protection surfacing welding to repair or manufacture grinding coal roller. By adjusting the composition of flux-cored wire, a self-protective and wear-resistant surfacing flux-cored wire can be developed to meet the requirements of the practical application of the surfacing welding of grinding coal roll, taking the iron-base high-chromium bright arc surfacing alloy as the research object in this paper. The surfacing alloy was prepared on Q235A substrate by self-shielded open arc welding with flux-cored wire. The microstructure was observed and analyzed by means of optical microscope, scanning electron microscope and its subsidiary electron energy spectrometer, X-ray diffractometer. The properties were studied by macrohardness test and wet sand abrasive wear test. Firstly, the microstructure and properties of hypereutectic high chromium open arc surfacing alloy with different carbon content were studied. The results show that the microstructure of high chromium open arc surfacing alloy is composed of primary carbides M7C3 and eutectic matrix, and with the increase of carbon content in the alloy, The number and size of primary carbides M7C3 increased, the volume fraction of carbides in microstructure increased significantly, the number of matrix decreased, and the effect of eutectic carbide continuity on matrix cleavage increased, resulting in the decrease of alloy toughness. The effect of carbon content on hardness and wear resistance of high chromium bright arc surfacing alloy is significant. With the increase of carbon content, hardness increases and wear resistance decreases. When the carbon content is high, the micro-exfoliation becomes the main reason for the decrease of wear resistance of the high chromium surfacing alloy, and the improvement of the wear resistance of the high chromium surfacing alloy should pay attention to the improvement of its toughness. Secondly, the effects of the alloying elements boron, tungsten, vanadium, titanium and niobium on the microstructure and properties of high chromium bright arc surfacing alloys were studied by adding different amounts of ferric boron, ferrovanadium, tungsten, vanadium, titanium and niobium into the flux-cored wire respectively. The results show that boron can make the eutectic point shift to the left, promote the formation of primary carbides M7C3, and form high hardness boride or carboboron compounds in the microstructure, which can significantly increase the hardness of surfacing alloy, but excessive boron can increase the brittleness of the alloy and decrease its wear resistance. Vanadium has agglomeration effect on carbon atoms, which can change the carbon concentration distribution of melt, increase the volume fraction of primary M7C3 phase and inhibit the formation of brittle microstructure. Tungsten can make eutectic point of high chromium alloy move to the left, increase M7C3 volume fraction of primary carbides, reduce the amount of eutectic carbides, increase austenite in matrix structure, and improve the toughness of alloy. The addition of titanium makes the melt precipitate TiC,TiC as the heterogeneous nucleation core of primary M7C3 and 纬-Fe, increases their nucleation rate, refines the primary phase and matrix structure, and improves the toughness of the alloy. However, too much titanium can make the residual melt carbon poor and inhibit the formation of primary M7C3. All niobium in high chromium alloy exists in the form of NbC and NbC dispersion distribution can refine the grain and increase the toughness of the alloy. It is beneficial to improve the hardness and wear resistance of the surfacing alloy.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG422.3
【参考文献】
相关期刊论文 前1条
1 牛冲;;堆焊技术在立式磨磨辊制造中的应用浅析[J];价值工程;2012年29期
，本文编号：2340712
本文链接：https://www.wllwen.com/kejilunwen/jinshugongy/2340712.html
教材专著
